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Royal Government of Bhutan

Ministry of Works and Human Settlement

Department of Roads

Construction of Bhalujhora Bridge on Pasakha Access Road

SASEC Road Connectivity Project

TECHNICAL SPECIFICATIONS

Section 6: Employer’s Requirement (ERQ)

Issued on: July 4, 2017

Invitation for NCB No: NCB/SASEC/DOR/2017-18/PAR-01

(Package-l)

PREFACE

The Technical Specifications cover the desired procedures and techniques to execute the works contained in the Bill of Quantities and Drawings of the Contract, for operation of plants and equipments, quality control of materials and workmanship. The Technical Specifications shall be read in conjunction with all other contract documents including the Bill of Quantities, Environmental Codes of Practice, Roads & Highways and the IEE/EIA report. This Technical Specification is an integral part of the contract and the Contractor is required to comply fully with all aspects of this Specification.

In case of omissions, discrepancies and ambiguities in the Technical Specifications, any other relevant international standards/references/codes shall govern.

The terminology “Engineer” in these Technical Specifications shall be read or understood as Project Manager (Supervision Consultant) appointed by the Client who shall supervise and be in charge of the work, and act on behalf of the Employer/Client. The Sections and Sub-Sections mentioned in these Specifications deem to apply those of these Specifications only, if otherwise not specified. The Specifications or Technical Specifications shall denote the same meaning of the specifications.

Technical Specifications for Construction of Bhalujhora Bridge

ABBREVIATIONS

AASHTO American Association of State Highway and Transportation Officials AC Asphalt Concrete ACV Aggregate Crushing Value AIV Aggregate Impact Value ALD Average Least Dimension ASTM American Society of Testing and Materials BOQ Bill of Quantities BS British Standards BSCP British Standards Code of Practice BSR Bhutan Schedule of Rates CBR California Bearing Ratio c/c center to center CR Crushing Ratio Cu.m Cubic metre DCP Dynamic Cone Penetrometer DoFS Department of Forestry Services DOR Department of Roads DGM Department of Geology and Mines dia DSA

Diameter Daily Subsistence Allowance

ECOP Environment Code of Practice for Highways and Roads EMP Environmental Management Plan FI Flakiness Index GCC General Conditions of Contract HMAC Hot mix asphalt concrete HWL High Water Level IRC Indian Road Congress (i.e. Recommended Code of Practice by IRC) IS Indian Standards ISO International Organization for Standardization LAA Los Angeles Abrasion Value LWL Low Water Level MC Moisture Content MDD Maximum Dry Density min Minute MSL Mean Sea Level NEC National Environment Commission no Number (units), as in 6 no. No Number (order) as in No 6 OMC Optimum Moisture Content OPC Ordinary Portland Cement PCC Particular Conditions of Contract PI Plasticity Index PL Plastic Limit PM Plasticity Modulus (PI x % passing 0.425 mm sieve) PVC Polyvinyle Chloride QA Quality Assurance PS Provisional Sum QC Quality Control RGoB Royal Government of Bhutan RROW Road Right of Way SE Sand Equivalent sec Second SG Specific Gravity SI International Standard Units of Measurements SSS Sodium Sulphate Soundness test, loss on 5 cycles STV Standard Tar Viscosity Sq.m Square metre TS Tensile Strength

Technical Specifications for Construction of Bhalujhora bridge

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UC Uniformity Coefficient UCS Unconfined Compressive Strength VIM Voids in Mix w/c Water cement ratio wt Weight % Percent


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Table of Contents 1.0 SECTION 1 - GENERAL AND SITEESTABLISHMENT 8

1.1 GENERAL 8 1.1.1 Scope of Work 8

1.1.2 Site Acquaintance 8

1.1.3 Specifications 8

1.1.4 Reference to Bureau of Indian Standards Codes & Other Codes 8

1.1.5 Dimensions & Levels 8

1.1.6 Notice of operation 8

1.1.7 Work program 8

1.1.8 Time Schedule 8

1.1.9 Drawings 8

1.1.10 Sub-Contracting 9

1.1.11 Compliance 9

1.1.12 Supply of Materials 9

1.1.13 Ordering Materials 9

1.1.14 Material Quality 9

1.1.15 Equipment & Facilities 9

1.1.16 Work Site Register (Site Order Book) 10

1.1.17 Area for the Contractor 10

1.1.18 Unit of measurement 10

1.2 SITE ESTABLISHMENT 10 1.2.1 Establishment of temporary infrastructure and facilities 10

1.2.1.1 Contractor’s site office 10

1.2.1.2 Labour Camps 11

1.2.1.3 Waste Management 11


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1.2.1.4 Material Storage 11

1.2.1.5 Temporary Drainage System 11

1.2.1.6 Site Water Supply and Electricity 11

1.2.2 Additional facilities to be provided 11 1.2.2.1 Survey Equipment 11

1.2.2.2 Sign Boards 12

1.2.3 Testing of Materials 12 1.2.3.1 Contractor’s Site Laboratory 12

1.2.3.2 Materials Testing by Independent Laboratories 13

1.2.3.3 Staff for Materials Testing 13

1.2.3.4 Sampling and Testing 13

1.3 General Contractor’s Obligations 14 1.3.1 Insurance 14

1.3.2 Safety measures and penalties 14

1.3.3 Protection of the Environment 14

1.3.4 As-Built Drawings 14

1.4 Maintenance and demobilization 15 1.5 Measurement and Payment 15

2 SECTION 2 - EARTHWORKS 16

2.1 General 16 2.2 Setting out 16 2.3 Stripping and storing topsoil 16 2.4 Excavation 17 2.5 Methods, tools and equipment 17 2.6 Rocks excavation 17 2.7 Blasting 18 2.8 Disposal of Excavated Material 18 2.9 Cofferdams 18 2.10 Pumping and Bailing 19 2.11 Filling 19

2.11.1 Foundation Fill Material 19

2.11.2 Backfill Material 20


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2.11.3 Backfilling 20

2.12 Plate Load Test on Foundations 20 2.13 Measurements 21 2.14 Payment 21

3 SECTION3 - CONCRETE WORK 22

3.1 Standards 22 3.2 Description 22 3.3 Materials 22

3.3.1 Specifications for Materials 22

3.3.2 Testing of Materials 25

3.3.3 Composition of Concrete 26

3.3.4 Control of Concrete Quality 29

3.4 Construction Methods 31 3.4.1 General 31

3.4.2 Care and Storage of Concrete Materials 31

3.4.3 Preparations before Casting 32

3.4.4 Measuring Materials 32

3.4.5 Mixing Concrete 32

3.4.6 Handling and Placing Concrete 35

3.4.7 Perforations and Embedment of Special Devices 38

3.4.8 Finishing Concrete Surfaces 38

3.4.9 Construction Joints 39

3.4.10 Curing Concrete 40

3.4.11 Removal of Scaffolding and Formwork 40

3.4.12 Repair of Concrete 40

3.4.13 Depositing Concrete under Water 41

3.4.14 Factory Made Precast Concrete Elements 41

3.4.15 Control of Heat in Structures 42


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3.4.16 Loading 42

3.4.17 Backfill to Structures 42

3.4.18 Cleaning Up 42

3.5 Measurement 42 3.6 Payment 43 3.7 Formwork and Scaffolding 43

3.7.1 Scaffolding (Falsework) 43

3.7.2 Formwork 44

3.7.5 Approval of Scaffolding and Formwork 45

3.7.6 Special Formwork 46

3.7.7 Removal of Form Work 46

3.7.8 Measurements 47

3.7.9 Payment 47

3.8 REINFORCEMENT 47 3.8.1 Description 47

3.8.2 Materials 47

3.8.3 Construction Methods 48

3.8.4 Measurement 49

3.8.5 Payment 50

3.9 PRESTRESSING WORKS 50 3.9.1 Description 50

3.9.2 Materials 50 3.9.3 Construction Methods 50

3.9.4 Payment 51

4 SECTION 4–MISCELLANEOUS 52

4.1 DRAINAGE FOR STRUCTURES 52

4.1.1 Description 52

4.1.2 Drainage Spouts 52


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4.2 HDPE DRAINAGE PIPES 53 4.2.2 Measurement 53

4.2.3 Payment 53

4.3 ELASTOMERIC BRIDGE BEARINGS 53 4.3.1 Scope 53

4.3.2 Steel reinforced Elastomeric Bearings 53

4.3.3 Properties of Elastomer 54

4.3.4 Steel Laminates 54

4.3.5 Bond 54

4.3.6 Manufacture 54

4.3.7 Fabrication Tolerances 54

4.3.8 Marking and Certifying 55

4.3.9 Testing 55

4.3.10 Installation 56


4.3.12 Payment 56

4.4 MOVEMENT OR EXPANSION JOINTS 56 4.4.1 Scope of Work 56

4.4.2 Specification for Strip Seal Expansion Joint 57


4.4.3 Payment 60

4.5 BRIDGE RAILING 60 4.5.1 Scope 60

4.5.2 Material 60

4.5.3 Placement 61


4.5.5 Payment 61


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5 SECTION 5 -STONE MASONRY WORK 62

5.1 Scope 62 5.2 Materials 62 5.3 Construction 63

5.4 Random Rubble – Coursed or Uncoursed 64

5.5 Dry Random Rubble 65

5.6 Composite Random Rubble 65

5.7 Stone Pitching 65

5.8 Stone Soling 66

5.9 Test and Standard for Acceptance 66

5.10 Measurement 66

5.11 Payment 66

6 SECTION 6 -GABION WORK 67

6.1 Scope 67 6.2 Materials 67

6.3 Construction of Gabions 68 6.4 Test and Standard for Acceptance 70 6.5 Measurement 71 6.6 Payment 71

LIST OF TABLES Table 2.11-1 Grading of foundation fill material ............................................................... 19

Table 3.3-1 Grading Requirements Coarse Aggregate ................................................... 24

Table 3.3-2 Grading Requirements for Fine Aggregate .................................................. 25

Table 3.3-3 Concrete classes .............................................................................................. 27

Table 3.8-1 Removal of Form Work ................................................................................... 46

Table 4.4-1 Strip Seal Element Specifications ................................................................. 58


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1.0 SECTION 1 - GENERAL AND SITE ESTABLISHMENT

1.1 GENERAL

1.1.1 Scope of Work

The Scope of work covered by his specifications is for the construction of Bhalujhora bridge on Pasakha Access road.

1.1.2 Site Acquaintance

The Contractor shall be deemed to have made himself/herself fully acquainted with the full nature of the work, the location and character of the bridge site and means of access to the site, including any traffic restrictions imposed. The construction site is an area within 1 Km radius of the location of the bridge.

1.1.3 Specifications

The work shall be executed in accordance with the technical specifications, the drawings, the Bill of Quantities and the instructions issued by the Client and/or Client’s Representative from time to time. Wherever these specifications are found wanting in anyway, the latest edition of standard specification for Bridges as approved by the Client shall be followed.

1.1.4 Reference to Bureau of Indian Standards Codes & Other Codes

The Standard Specifications & Codes of Practices explicitly referred to in these Specifications or other related standard codes etc. shall be of latest editions, current at the time of tendering including all amendments published before that date.

1.1.5 Dimensions & Levels

All dimensions and levels shown on the Drawings shall be verified by the Contractor at the site and he/she will be held responsible for the accuracy and maintenance of all dimensions and levels. Figured dimensions are in all cases to be accepted and no dimensions shall be scaled. Large scale details shall take precedence over small scale drawings. In case of discrepancy the Contractor shall ask for clarifications from the Engineer before proceeding with the work.

1.1.6 Notice of operation

The Contractor shall not carry out any operations without the written approval of the Engineer.

1.1.7 Work program

The Contractor shall submit to the Engineer before commencement of the work, for his approval, a detailed program in the form of bar chart/Microsoft project etc. The submission and approval of such program shall not relieve the Contractor of any of his duties or responsibilities under the Contract.

1.1.8 Time Schedule

The Contractor shall follow the project master schedule and detailed activity schedule submitted after signing the contract. The contractor may submit minor changes on schedule to the Engineer for approval whenever necessary.

1.1.9 Drawings

The Contractor will receive free of cost one complete set of all drawings necessary to complete the work and the Contractor have to include in his Tender for any additional copies of drawings required by him. One copy of the full set of drawings shall be retained at the site.


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1.1.10 Sub-Contracting

Should the Contactor consider it necessary to sub-contract any part of his work, the Sub-Contractor and the scope of the work proposed to be sub contracted has to be approved by the Engineer/Client. It will be the responsibility of the Contractor to ensure that the sub-contracted works are carried out in accordance with the specifications and relevant drawings.

1.1.11 Compliance

All workmanship, materials and tests (where required) shall comply with the appropriate Indian or American Standards as specified or approved and shall be in accordance with the drawings all to the satisfaction of the Client/Engineer.

1.1.12 Supply of Materials

a. The Contractor shall supply certificates of compliance with specified Indian Standards for all materials supplied for the works. Manufacturer’s catalogues and samples of materials proposed for procurement and to be used in the works shall be submitted to the Engineer/Client for approval, before procurement.

b. Materials procured without specific approval of the Engineer/Client shall not be allowed to be used in the works.

c. The Contractor’s quoted rate shall include but not limited to:

i. Preparation and submission of shop drawings wherever necessary, calculation sheets, schedule of materials, and providing catalogues about, and samples of materials, and obtaining approval from the Engineer/Client.

ii. Carryout of mix design, sampling and testing of construction materials, preparation and testing of trial mixes, preparation and testing of concrete test cubes, and obtaining approval from the Engineer/Client.

iii. Transporting to the Site, including loading and unloading.

iv. Providing certificates of compliance with required relevant standards, as specified.

v. Storing and protection of the materials at the Site.

1.1.13 Ordering Materials

The Contractor is entirely responsible for assessing the quantities of materials to be ordered for use in the works.

1.1.14 Material Quality

The Contractor should note that the qualities of all materials used shall be scrutinized, monitored and checked by the Engineer/Client. All materials used have to fulfill the requirements and specifications given in the drawings and in the relevant code of practice. If the Contractor is asked to supply certificate of origin of the supplied and used materials, he has to do so within a reasonable timeframe fixed by the Engineer.

1.1.15 Equipment & Facilities

The Contractor shall provide and operate equipment and facilities to load, offload, shift, move, transport, stack and place all types of steel parts and materials at the bridge site as well as at the Contractor’s yard. The Contractor shall also provide all lifting equipment and facilities to lift, shift, stack, load, unload and handle all type of steel parts and materials at the bridge site as well as at the Contractor’s yard.


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1.1.16 Work Site Register (Site Order Book)

The Contractor shall keep a Work Site Register (Site Order Book) at the Site in which all the remarks, instructions, decisions of the Engineer/Client and the essential details of the work shall be recorded. The Contractor shall keep the records of all daily information of the works in this register as required by the Engineer/Client. It shall be readily available in the office for inspection.

1.1.17 Area for the Contractor

i. The Contractor shall be provided a site office and workers’ camps in the vicinity of the bridge site.

ii. The Contractor shall maintain and furnish the site office and the camps with the basic required facilities acceptable to the Engineer/Client. These shall be provided by the Contractor at no extra cost.

1.1.18 Unit of measurement

The following units of measurement & abbreviations shall be used.

Unit Abbreviation Millimeter Mm Meter M Square millimeter mm2 Square meter Sq.m Hectare Ha Cubic metre Cu.m Kilogram Kg Tonne Ton Sum Sum Number no. Hour Hr Week wk (7 days) Pieces Pcs

1.2 SITE ESTABLISHMENT

1.2.1 Establishment of temporary infrastructure and facilities

As part of the site establishment, the contractor shall build and maintain all temporary infrastructures such as stores, workshops, contractor's yard, access roads etc. for smooth implementation of the works.

The following facilities, but not limited to, shall be installed/built and maintained by the contractor as a part of the site establishment:-

1.2.1.1 Contractor’s site office

The contractor shall use the already constructed site office and maintain it with the required sanitary facilities during the project duration. The contractor’s site office have to be furnished with all the required office equipments and furniture.


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1.2.1.2 Labour Camps

The contractor shall use the already constructed labor camps and maintain it with sufficient sanitary facilities, sufficient and safe drinking water. Sufficient supply of electric power has to be made available at all times during the project duration. If the labor camps are not found sufficient for large number of labors at any point in time, additional camps should be constructed at the cost of the Contractor.

1.2.1.3 Waste Management

A proper waste management facility and system have to be put in place to maintain general cleanliness of the site and upkeep hygiene of the personnel and laborers working at the bridge site. The proposed facilities have to be approved by the Engineer.

1.2.1.4 Material Storage

Construction materials have to be stored well under sheds to avoid quality degradation and loss.

Minimum following facilities have to be erected at the bridge site as part of site establishment for material storage:-

• Cement store – min. plan area 30 m2, CC flooring, tin wall & roof (water tight and limited air circulation) - 1 no.

• General store – min. plan area 25 m2, CC flooring, bamboo

mat/ekra wall and tin roof -1 no.

1.2.1.5 Temporary Drainage System

The Contractor shall build a temporary drainage system at the site to drain out waste water. The layout and design of the drains have to be approved by the Engineer.

1.2.1.6 Site Water Supply and Electricity

The Contractor shall make his own arrangements for water and electric supply and pay for them. The water supplied must be potable and must be free from salts, oils, acids, arsenic and other substances harmful to health. The water shall be tested to confirm its portability. While a water supply line has been installed at site, the Contractor shall maintain it and ensure enough water supply. Electricity supply has to be installed from BPC at the Contractor’s cost.

If the Contractor intends to use electrically operated construction equipment and machinery, matching number and capacity of generators have to be installed at the bridge site.

1.2.2 Additional facilities to be provided

As part of the site installation, the contractor shall provide/build/install following additional facilities:-

1.2.2.1 Survey Equipment

The Contractor will be required to provide survey equipment for the use of the Contractor and Engineer and his staff. The equipment and all its accessories shall be available at all times at the bridge site during the contract period and shall be maintained in good working order. For higher accuracy and better ease of use, the equipment shall be Total Station or equivalent. The contractor shall depute appropriately qualified and trained personnel to operate the survey equipment at all times during the contract period.


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The survey equipment and its accessories (legs, reflectors and stands, rechargeable batteries and charger etc.) shall be from any reputable manufacturer. The range, accuracy, least count etc. of the equipment has to be approved by the Engineer.

1.2.2.2 Sign Boards

The Contractor shall provide identification sign boards and maintain them in good condition. All information on the signboards will be written in English and Dzongkha. The signboards will be positioned as directed by the Engineer.

Each sign shall show:

• the name of the Project • the name of the Employer • name of the Contractor • Contract start and completion dates • Contract amount • Any other details as required by the Engineer

Project Signboards shall have steel pipe posts of diameter from 75mm to 100mm with 3mm thick steel plates. The steel pipe legs shall be embedded in the ground. The design of the signpost and the information content on it shall be approved by the Engineer.

The contractor shall install at least one sign board at the bridge site, the location of which shall be approved by the Engineer.

The Contractor shall remove the sign boards on completion of the Works or when instructed by the Engineer

1.2.3 Testing of Materials

1.2.3.1 Contractor’s Site Laboratory

The Contractor shall maintain the existing Site Laboratory for the use of the Contractor and the Engineer.

The laboratory shall be provided with enough consumable stocks necessary to carry out the tests listed below:-

1. Moisture Content 2. Particle Size Distribution 3. Standard Compaction 4. Flakiness Index 5. Fineness Modulus 6. Slump Test 7. Concrete Crushing Strength 8. Any other tests required as instructed by the Engineer

The Contractor would be also required to procure the following equipment for quality assurance tests as part of site establishment:

1. Mortar Cube mould – 12 pieces 2. Concrete cube mould – 12 pieces

The Contractor shall maintain the laboratory, furniture, fittings and testing equipment for the duration of the Contract and replace any part or item that is irreparably damaged or lost. The Contractor shall


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pay all expenses in respect of water, electricity and other consumables necessary for the running of the laboratory and shall arrange for the laboratory to be regularly cleaned.

The Contractor shall not be permitted to commence permanent works requiring on-site testing till the Site laboratory is functional in all respects, unless temporary testing procedures proposed by the Contractor have been approved by the Engineer.

At the end of the Contract, all materials recovered from dismantling the laboratory, together with all furniture, fittings and testing equipment will be the property of the Client.

1.2.3.2 Materials Testing by Independent Laboratories

In addition to the above mentioned tests the Contractor shall arrange for the following tests to be carried out at off-site testing facilities as and when instructed by the Engineer:

1. Tests on reinforcing steel 2. Tests on cement – fineness, setting time and strength 3. Aggregate crushing value 4. Any other tests as may be instructed by the Engineer

The Contractor shall be responsible for arranging off-Site laboratory tests, and all other tests. These tests shall be performed by off-site standard testing laboratories proposed by the contractor and as approved by the Engineer. All the expenses for such tests shall be borne by the contractor including the DSA and travel/transport expenses as per RGoB rules for the Client and Engineer’s staff, equipment and test specimens. The Contractor shall be responsible for all attendance of staff from these approved testing laboratories.

1.2.3.3 Staff for Materials Testing

The contractor shall at all times make available the Material engineer and Lab. Technician to carry out sampling and testing of materials in accordance with Specifications.

1.2.3.4 Sampling and Testing

For Concrete Mixes, 1 set of tests per 100 m3 of aggregate for shape, grading, ACV/10% Fines should be carried out or as instructed by the Engineer.

The Contractor shall maintain complete records of test results, which may be inspected by the Engineer at any time. All test results shall be recorded on standard forms approved by the Engineer and shall be signed by the Contractor’s engineer or technician in charge of the laboratory. Completed forms shall clearly show the locations of samples, sampling dates and testing dates. Samples shall be numbered serially at the time of sampling. A copy of all test results should be submitted to the Engineer immediately after completion of the test.

The Engineer will be informed prior to any sampling or testing carried out in the laboratory and will have the right to use the facilities and equipment to make his own tests. The Contractor shall have the right to witness any sampling or testing carried out by the Engineer. On completion of the Contract the original copies of all test results shall be handed over to the Employer, via the Engineer.


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1.3 General Contractor’s Obligations

1.3.1 Insurance

The contractor shall obtain all risk insurance for the work, plant, equipment, personnel and labor. The modalities for the insurance shall be as per the stipulations under Clause 19 of General Conditions of Contract (GCC).

1.3.2 Safety measures and penalties

The regulations and guidelines for Work Place Safety issued by Ministry of Labor and Human Resources, RGoB shall be complied with at all times. The workers and the personnel shall have safe and secure working conditions at the construction site at all times and there shall be no compromise on the work place safety. The workers shall wear safety gears – helmets, boots, belts, harness, goggles, hand gloves, welding masks etc. as may be appropriate, at the work site at all times. The Contractor shall issue the required protective clothing and safety equipment to all his employees and provide the first aid boxes within one month of the commencement of the Contract. He is responsible for ensuring that all his employees make appropriate use of the items and maintain them in good order. The Contractor shall replace damaged, worn-out, exhausted or out of date items as necessary.

The Contractor shall build temporary scaffold, temporary stairs, working platforms, fall-down-stoppers and such other measures to allow safe and proper execution and check of the construction works. Anybody entering the worksite shall wear safety helmets at all times. If scaffold, working platforms etc. are not possible or not required, the personnel and the workers have to wear safety belts. The quality of the safety belts has to be approved by the Engineer.

1.3.3 Protection of the Environment

The Contractor has to comply with his obligations for safety, security and protection of the environment as described in the relevant sections/clauses of the Contract. The Contractor is not allowed to dispose or dump any kind of waste materials into the river. The contractor has to, at the end of the project, remove and clean the affected waterway and all the temporary constructions that it has built for the purpose of securing temporary supports or restraints for the permanent structures, installations for safety measures etc. and which do not ultimately form the part of the permanent structure.

1.3.4 As-Built Drawings

The Contractor shall furnish sets of as-built Drawings of the Works to the Engineer, showing the permanent works as actually constructed, within 45 days of completion of the Works. Included in the sets of as-built Drawings will be revisions of Tender Drawings and Drawings supplied to the Contractor during the Contract as well as revisions of drawings supplied by the Contractor during the Contract. The As-built drawings submitted by the Contractor will be subject to the approval of the Engineer.

1.3.5 Construction Drawings

a) The Contractor shall prepare and submit construction drawings for details of construction work, temporary or permanent works, if required under the contract.

b) The construction drawings shall show at a suitable scale all the particulars of the work including dimension, materials, finishes, lines, levels, tolerances and other details to show compliance with the specification, the suitability of item for its compliance.


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c) The Engineer and his representatives will review the drawings only for their general compliance with the intent of the drawings and specifications. Responsibility for accuracy of dimensions, technical design, performance and suitability for intended purpose of the items shall remain with the Contractor.

d) Four (4) copies of each construction drawing shall be submitted in sufficient time to allow for review, possible revisions and resubmission for approval prior to ordering materials, coordinating all affected and contingent work without delay to the schedule of construction.

e) Two copies of all construction drawings will be retained by the Engineer. The remaining copies will be returned to the Contractor signed by a representative of the Engineer and marked “REVIEWED” with either:

- a request for resubmission and notes as to deficiencies; - a note indicating the drawing has been reviewed but is subject to conditions noted or

listed, and does not require resubmission; or - a note indicating the drawing has been reviewed and is considered to meet the intent

of the design and does not require resubmission.

f) The drawings shall be submitted at least two weeks before the commencement of construction of work for which these drawings are intended.

g) Construction should not commence until the drawings have been reviewed and are returned under the Conditions of Contract except where instructed by the Engineer.

h) The materials or products should not be ordered until drawings have been reviewed and are returned under Conditions of Contract except when instructed by the Engineer.

1.4 Maintenance and demobilization

The Contractor shall properly maintain all the infrastructures at the site such as office, stores, yards, labor camps etc. till the end of the Project. At the end of the Project, the Contractor has to remove and demobilize all the temporary infrastructures that it has built and restore the bridge site to its original condition and shape. The dismantling and demobilization shall be completed within the stipulated contract duration.

1.5 Measurement and Payment

The site establishment shall include cost of all temporary infrastructure facilities he is required to built, tools and plants, safety gears etc. as described under Section 1.2.of this specification. The quantity, size and other specifications of various facilities mentioned here are the minimum requirements. While the minimum requirements have to be fulfilled to be eligible for payment under site installation, the contractor may add to what is specified here for fast tracking or smooth implementation of the project at his own cost. If the Engineer finds the site facilities provided by the contractor as per the minimum requirement in this specification inadequate for smooth or proper implementation of the works, he will have the right to demand the contractor to install/provide additional facilities/installations for which contractor cannot claim additional payment.


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2 SECTION 2 - EARTHWORKS

2.1 General

This work shall consist of excavation, removal and satisfactory disposal of all materials necessary for the construction in accordance with requirements of these specifications and the lines, grades and cross-sections shown in the drawings or as indicated by the Engineer. It shall also include backfilling of the excavated foundations not occupied by the structures and compacted filling with suitable materials of the abutments, return walls, wing walls and retaining walls. The excavation shall be deemed to be carried out by machine. For excavation by machines, materials shall be classified as:-

All kinds of soil

Generally any strata, such as sand, gravel, loam, clay, mud, black cotton soil, moorum, shingle, river bed boulders, soiling of roads, paths etc. and hard core macadam surface of any description (water bound, grouted tarmac etc.), lime concrete, mud concrete and their mixtures. This category includes both ordinary and hard soil.RKS 2009

All kinds of rocks

This includes all categories of rocks - ordinary rock, hard rock requiring/not requiring blasting, hard rock requiring chiselling. This category doesn’t include hard rock excavation/cutting in the areas where conventional blasting is prohibited and requires silent blasting operation. The rock cutting by silent blasting if required shall be measured and paid for separately.

2.2 Setting out

After the site has been cleared, the limits of excavation shall be set out true to lines, curves, slopes, grades and sections as shown on the drawings or as directed by the Engineer. The Contractor shall provide all labour, survey instruments and materials such as strings, pegs, nails, bamboos, stones, lime, mortar, concrete, etc., required in connection with the setting out of works and the establishments of bench marks. The Contractor shall be responsible for the maintenance of the benchmarks and other marks and stakes as long as, in the opinion of the Engineer, they are required for the work. The ground levels shall be taken at 5m to 15m intervals in uniformly sloping ground and at closer intervals where local mounds, pits or undulations are met with. The ground levels shall be recorded in field books and plotted on plans. Plans shall be drawn to a suitable scale and North direction and position of benchmark shall be shown on the plans. The contractor and the Engineer shall sign the plan before the earthwork is started. The contractor at his own cost shall supply the labour required for taking levels.

2.3 Stripping and storing topsoil

When so directed by the Engineer, the topsoil existing over the sites of excavation shall be stripped to specify depths and stockpiled at designated locations for re-use in covering embankment slopes, cut slopes, and other disturbed areas where re-vegetation is desired. Prior to stripping the topsoil, all trees, shrubs etc. shall be removed along with their roots, with the approval of the Engineer.


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2.4 Excavation

All excavations shall be carried out in conformity with the directions laid herein-under and in a manner approved by the Engineer. The works shall be done such that the suitable materials available from excavation are satisfactorily utilized as decided upon beforehand. While planning of excavations, the Contractor shall take all adequate precautions against soil erosion, water pollution etc. and take appropriate drainage measures to keep the sites free of water. The excavations shall conform to the lines, grades, side slopes and levels shown on the drawings or as directed by the Engineer. The Contractor shall not excavate outside the limits of excavation. Subject to the permitted tolerances, any excess depth/ width excavated beyond the specified levels/dimensions on the drawings shall be made good at the cost of the Contractor with the suitable material of characteristics similar to that removed and compacted. All debris and loose materials on the slopes of cutting shall be removed. No backfilling shall be allowed to obtain required slopes except that when boulders or soft materials are encountered in the cut slopes, these shall be excavated to approved depth on instructions of the Engineer and the resulting cavities filled with suitable materials and thoroughly compacted in an approved manner. 4 After excavation, the sides of the excavated areas shall be trimmed and the area contoured to minimize erosion and ponding, allow for natural drainage to take place. If trees were removed, new trees shall be planted, as directed by the Engineer. The cost of planting new trees shall be deemed to be incidental to the work. The elevations of the bottoms of footings shown on the Drawings are approximate only and the Engineer may order in writing such changes in the dimensions or elevations of footings as may be deemed necessary to secure a satisfactory foundation.

Boulders, logs and other objectionable material encountered in excavation shall be removed. After each excavation is complete the Contractor shall notify the Engineer to that effect and no footings, bedding material or structure shall be placed until the Engineer has approved the depth of excavation and the character of the foundation material.

The foundation material shall be cleared of all loose material and cut to a firm surface, either level or stepped or serrated, as specified or shown on the Drawings or directed by the Engineer.

2.5 Methods, tools and equipment

Only such methods, tools and equipment as approved by the Engineer shall be adopted/used in the work. If so desired by the Engineer, the Contractor shall demonstrate the efficacy of the type of equipment to be used before the commencement of the work. Methods, tools and equipment to be adopted for the work shall be such which will not affect the property to be preserved.

2.6 Rocks excavation

Excavation in ordinary rock shall be carried out by crowbars, pickaxes or pneumatic drills.

Blasting operations are generally not required in this case. If the contractor wishes to resort to blasting, he can do so with the permission of Engineer, but nothing extra will be paid to him on this account.


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Excavation in hard rock shall be done by chiseling where blasting operation is prohibited or is not applicable. In trenches or drains where blasting is not otherwise prohibited, the excavation in hard rock shall be carried out by blasting in the first instance and finally by chiseling so as to obtain the correct section of the trench as per drawing. The blasting operation shall be strictly as per latest RGOB blasting manuals.

2.7 Blasting

The contractor shall obtain approval from the competent authority for procuring and storing the explosives. The contractor shall procure the explosives, fuses, detonators etc. From the Government designated/appointed firms. The Engineer or his representative shall have the right to check the contractor's store and accounts of explosives. The contractor shall provide facilities for this. All blasting work shall be carried out by a licensed personnel and the contractor shall take all precautions as per rules for blasting operations. The contractor shall be responsible for any damage arising out of accident to the workmen, public or property due to storage, transportation and use of explosive during blasting operations.

2.8 Disposal of Excavated Material

Excavated material classified as suitable by the Engineer shall generally be utilized as backfill or embankment fill. Surplus suitable material shall be stockpiled at the Site. Excavated suitable material for use as backfill shall be deposited by the Contractor in spoil heaps at points convenient for re-handling of the material during the backfilling operation and approved by the Engineer.

Excavated material classified as unsuitable as backfill by the Engineer shall be carried to waste.

Excavated material shall be deposited in such places and in such a manner as not to cause damage to roads, services or property either within or outside the right-of-way and so as to cause no impediment to the drainage of the site or surrounding area. The location of spoil heaps shall be subject to the approval of the Engineer who may require that the reference lines and the traverse lines of any part of the structure be kept free of obstruction.

2.9 Cofferdams

The term “cofferdam” denotes any temporary or removable structure, constructed to hold the surrounding earth, water or both, out of the excavation, whether such structure is constructed of earth, timber, steel, concrete or any combination of these. The term includes earth dikes, timber cribs, sheet piling, removable steel shells and all bracing; and it shall be understood to include excavation enclosed by pumping wells and well points.

The cost of cofferdams, if required to be provided, is always to be included in the tender rates/prices for the permanent work and shall not be paid extra.

The Contractor shall submit upon request, drawings showing his proposed method of cofferdam construction. Approval of the drawings by the Engineer will not in any way relieve the Contractor of the responsibility for the adequacy of the design for strength and stability.

Unless specified otherwise, the cofferdams shall be removed after the completion of the sub-structure. The removal shall be effected in such a manner as not to disturb or destroy the finished work. The Engineer may order the Contractor to leave any part or the whole of the cofferdam in place.


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When encountered with conditions which, in the opinion of the Engineer, render it impossible to de-water the foundation before placing the footing, the Engineer may require the construction of a concrete foundation or seal of such dimensions as he may consider necessary, and of such thickness as to resist any possible uplift. The concrete for such seal shall be placed as shown on the Drawings or required by the Engineer. The foundation shall then be de-watered and the footing placed. When weighted cribs are used and the weight is used to overcome partially the hydrostatic pressure acting against the bottom of the foundation seal, special anchorages such as dowels or keys shall be provided to transfer the entire weight of the crib to the foundation seal. When a foundation seal is placed under water the cofferdam shall be vented at low water as directed.

Cofferdams shall be constructed so as to protect newly cast concrete from sudden rising of the water and to prevent damage to the foundation by erosion.

2.10 Pumping and Bailing

Pumping and bailing from the interior of any foundation enclosure shall be done in such a manner as to preclude the possibility of the movement of water through or alongside any concrete being placed. No pumping or bailing will be permitted during the placing of concrete and for a period of at least 24 hours thereafter unless it is done from a suitable pump separated from the concrete work by a watertight wall or from well points.

Excavations shall be as dry as possible prior to and during placing concrete. Placing concrete under water will only be permitted if indicated on the Drawings or approved by the Engineer.

2.11 Filling

2.11.1 Foundation Fill Material

Material for foundation fill shall be a natural or artificial mixture of sand or other mineral aggregate, free from vegetable matter, soft particles and excess clay and shall consist of suitably graded sand to one of the grading envelopes A to C of Table 2.11-1, gravel or stone as shown on the Drawings or as required by the Engineer, or concrete. Concrete for foundation fill shall conform to the general requirements of Section3. Concrete to be placed under water shall conform to the requirements of Section 3.4.13. Concrete used as foundation fill in dry excavation shall be M15.

Table 2.11-1Grading of foundation fill material

A B C D E Nominal fineness modulus

Not less than 2.8

1.5-2.8 1.0-1.5 0.8-1.0 0.5-0.8

Sieve size (mm)

% passing by weight

10 100 100 100 100 100 5.0 90-95 95-100 100 100 100 2.4 70-90 90-100 100 100 100 1.2 45-70 70-95 95-100 100 100 0.6 25-45 40-80 85-100 95-100 100 0.3 10-20 10-50 50-80 70-90 80-95 0.15 0-2 0-20 5-25 15-40 30-60


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Grading outside the above limits may in certain circumstances be approved by the Engineer. Such permission shall be in writing.

2.11.2 Backfill Material

The excavated materials shall be used for backfilling if found suitable and approved by the Engineer. The source (borrow pit) and type of fill material have to be approved by the Engineer.

The earth shall be free from all roots, grass and rubbish. All lumps and clods exceeding 80mm in any direction shall be broken and each layer shall be consolidated by ramming and rolling, etc. Watering shall be done, if so stipulated. The top surface of the finally finished area shall be neatly dressed.

The finished formation levels, in case of filling shall be kept higher than the required levels, by making an allowance of 10% of depth of filling for future settlement in case of ordinary consolidated fills, and 5% in case where consolidation is done by heavy mechanical machinery under optimum moisture conditions.

2.11.3 Backfilling

All spaces excavated under these Specifications and not occupied by the permanent structure shall be backfilled. However, the finished level of the back fill shall be as per the lines and levels of the finished profile of the slope shown in the design drawings. Backfilled material shall fully comply with this Specification and adequate provision shall be made for drainage. No backfilling shall commence until permission has been given by the Engineer.

Backfilling shall be well compacted and shall be done in layers, not exceeding 200mm in each layer. Each layer shall be watered, rammed and consolidated before the succeeding one is laid. Special care shall be taken to prevent any unduly high pressure against the structures. In placing backfill and embankment, the material shall be placed insofar as possible to approximately the same height on both sides of the structure at the same time. If conditions require backfilling appreciably higher on one side, the additional material on the higher side shall not be placed until permission is given by the Engineer that the structure has enough strength to withstand any pressure created.

2.12 Plate Load Test on Foundations

After the foundation excavation is complete and prior to casting of footing slabs, the Contractor shall carry out plate load test on either of the two abutment foundations if the site conditions warrant testing subject to the judgement of the Engineer. The tests shall be carried out to determine bearing capacity of soil and its settlement in accordance with IS: 1888 Method of Load Test on Soils.

The Contractor shall be responsible for arranging equipment, tools and other materials necessary for carrying out test at site and determining bearing capacity of soil foundation at his own costs. The cost of carrying the plate load test is to be included in the tender rates/prices and shall not be paid extra.

The safe bearing capacity of foundations thus calculated from the plate load tests shall not be less than the safe bearing capacity assumed in the bridge design reports. If the safe bearing capacity of foundations are found to be less than that assumed during design, additional excavations shall be carried out for suitable depths and the soil underneath replaced with plain cement concrete (PCC) of class M15. The cost of carrying out additional excavations and providing replacement concrete, if necessary shall be paid as additional quantity.

If the plate load test results are unsatisfactory and inconclusive, the Contractor shall carry out additional plate load tests at his own cost as directed by the Engineer.


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2.13 Measurements

The volume of excavation shall be measured in cubic meters of excavated undisturbed material.

The quantity of excavation for structures to be measured for payment shall include excavation for all structures. The measured volume shall be the excavation plan outline, bounded on the bottom by the plane of the underside of the blinding concrete under the reinforced concrete footing and on the top by the surface of the existing ground and on the sides by vertical planes of the footings and the volume so measured shall be term as “Solid Volume”.

Additional excavations for slope cutting, working space and for other purposes of construction ease and convenience shall not be paid extra. The cost for such additional excavation works is deemed to be included in the unit rates under the payable items and quantities of the excavation works. The removal of slides, cave-ins, silting or filling shall also neither be measured nor paid for.

The soil/rock excavation for construction/widening of approach roads to the bridge however shall be measured as actual volume of excavation as per the drawings or as directed by the Engineer as per the actual requirement of the site. The contractor has to do a detail survey of the area to be excavated as per direction of the Engineer prior to and after the excavation to arrive at the actual volume of excavation. The measured volume shall be in-situ volume and no allowance shall be allowed for bulking and other forms of volume change.

The measured volume for backfilling and filling behind the abutment/return walls etc. shall be the backfilling plan outline bounded at the bottom by the plane of the underside of the blinding concrete under the reinforced concrete footing and on the top by the surface of the finished ground and on the sides by vertical planes of the footings minus the volume occupied by the permanent structure. However the areas around the foundations excavated by the contractor for creating working space, stabilizing excavation slope etc. shall be backfilled to required degree of compaction as per this specification at the contractor’s own cost.

The length, breadth and depth/height shall be measured correct to 10mm. In case the measurements are taken with staff and level, the level shall be recorded correct to 5mm and depth of cutting and heights of filling calculated correct to 5mm. The cubical contents shall be worked out to the nearest two places of decimal in cubic metres.

2.14 Payment

The rates shall cover the cost for carrying out all the required operations including cost of labour, materials, equipment hired/owned, tools and plants, and incidentals necessary to complete the work. In case of rock, the rate shall also include the cost of all operations of blasting with explosive and accessories as mentioned above.


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3 SECTION3 - CONCRETE WORK

3.1 Standards

The concrete materials, production, methods, testing and admixtures shall conform to the latest revisions of the following Indian Standards or, where not covered by these standards, to the equivalent International Standards:

IS: 8112 43 grade Ordinary Portland Cement. IS: 12269 53 grade Ordinary Portland Cement. IS: 383 Coarse & fine aggregates from natural sources for aggregates. IS: 456 Code of practice for plain & reinforced concrete. IS: 457 Code of practice for general construction of plain & reinforced concrete for dams &

other massive structures. IS: 516 Method of test for strength of concrete. IS: 1199 Methods of sampling & analysis of concrete. IS: 1489 Portland Pozzolana cement. IS: 2386 Methods of test for aggregates for concrete. IS: 2505 Concrete vibrators – immersion type – general. IS: 2506 General requirements for screed board concrete vibrators. IS: 4082 Stacking & storage of construction materials & components at site– recommendations. IS: 7861 Code of practice for extreme weather concreting. IS: 9103 Admixtures for concrete. IS: 10262 Recommended guidelines for concrete mix design. IRC: 112 Code o Practice for Concrete Road Bridges

In cases of conflict between or among the above standards and the specifications given herein, the decision of the Client/Engineer shall prevail.

3.2 Description

This work shall consist of the construction of all or portions of concrete structures, of the required grades and types, with or without reinforcement and with or without admixture, in accordance with these Specifications and to the lines, levels, grades and dimensions shown on the Drawings and as required by the Engineer.

The cement concrete shall consist of a mixture of cement, water and coarse and fine aggregate with or without admixture.

3.3 Materials

3.3.1 Specifications for Materials

A) Cement

Cement shall conform to the requirements of Indian Standard as mentioned in Article 3.1 of this specification unless other types are indicated on the Drawings or specified by the Engineer.

One of the types of the cements, specified below shall be used. a) Ordinary Portland cement conforming to IS: 269 b) Portland blast furnace slag cement conforming to IS: 455 e) Portland pozzolana cement conforming to IS: 1489


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Bagged or bulk cement which has partially set or which contains lumps of caked cement shall be rejected. The use of cement reclaimed from discarded or used bags shall not be permitted.

B) Water

Water used for mixing mortars and concrete shall be clean and reasonably free from injurious quantities of deleterious materials such as oils, acids, alkalis, salts and vegetable growth. Generally potable water shall be used. Where water can be shown to contain any sugar or an excess of acid, alkali or salt, the Engineer may refuse to permit its use. As a guide, the following concentrations may be taken to represent the maximum permissible limits of deleterious materials in water.

(a) Limits of acidity: - To neutralize 200 ml sample of water, it should not require more than 2 ml of 0.1 N caustic soda solutions.

(b) Limits of Alkalinity: - To neutralize 200 ml sample of water it should not require more than 0.1 ml of 0.1 N hydrochloric acid.

(c) Percentage of solids should not exceed: -

Organic 200 ppm (0.02%)

Inorganic 3000 ppm (0.30%)

Sulphates 500 ppm (0.05%)

Alkali chlorides 1000 ppm (0.1%)

Water found satisfactory for mixing is suitable for curing concrete. However, the water used for curing should not produce any objectionable stain or deposit on the concrete surface.

The use of river water will be subject to the approval of the Engineer. Such approvals may be withdrawn from time to time depending on the condition of the river.

C) Admixtures

Admixtures or any other additions shall not be used except with the written approval of the Engineer.

Admixtures, if specified or permitted, shall fully conform to the requirements of Indian Standard IS: 9103

D) Coarse Aggregate

Coarse aggregate for all types of concrete with the exception of blinding concrete shall consist of hard durable crushed or broken rock and generally conform to the requirements of Indian Standard IS:383 (or AASHTO Standard Specification M 80 or ASTM C33 / C33M – 08). Coarse aggregate shall be clean, free from dust and other deleterious material.

The amounts of deleterious substances shall not exceed the following limits:

1) Soft fragments; 2% by mass

2) Clay lumps; 0.25% by mass

3) Material Passing the 0.075 mm sieve; 0.50% by mass if clay,1.50% by mass if fractured dust

In addition, coarse aggregates shall comply with the following:


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1) Thin or elongated pieces; Flakiness Index less than 30

2) The aggregate crushing value shall be less than 30% and the ten percent fines value shall be greater than 150 kN.

The grading of coarse aggregate of shall conform to Table 3.3-1below.

Table 3.3-1 Grading Requirements Coarse Aggregate

In heavily reinforced structures with difficult casting conditions smaller size aggregates may be used if approved by the Engineer.

E) Fine Aggregate

Fine aggregate shall consist of natural sand and fine aggregates. Fine aggregates from different sources of supply shall not be mixed or stored in the same pile.

The amounts of deleterious substance when tested shall not exceed the following limits:

1) Friable Particles; 0.5% by mass

2) Coal and Lignite; 0.5% by mass

3) Material passing the 0.075 mm sieve; 3.0% by mass

4) Any other deleterious materials shall not cause a strength reduction of the concrete of more than 5% in relation to the strength of concrete free of the concerned deleterious material.

The grading shall normally be in accordance with Table 3.3-2. In the event that it is not possible to obtain regular supplies of sand conforming to this grading, the Engineer may approve the adoption of an alternate grading conforming to the requirements of the mix design. However, any additional cost results from changes in aggregate proportions or additional cement contents required to achieve the specified strengths, when using these alternative grading, shall be borne by the Contractor and shall not be reimbursed.


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Table 3.3-2 Grading Requirements for Fine Aggregate

Grading Requirements for Fine Aggregate

Sieve Size (mm) % Passing by Weight

10.0 100 5.0 95-100 1.2 45-80 0.30 10-30 0.15 2-10

3.3.2 Testing of Materials

A) Cement

Cement shall be in accordance with Indian Standard. The Contractor must provide the Engineer with manufacturer’s certificates indicating compliance.

Cement shall be sampled and tested for fineness, setting time and strength in accordance with IS:615 at the Contractor’s expense. The Contractor shall notify the Engineer of delivery dates so that there will be sufficient time for sampling the cement, either at the mill or upon delivery. If this is not done, the Contractor may be required to re-handle the cement in the store for the purpose of obtaining the required samples.

Sampling shall normally be instructed by the Engineer for every batch of cement prior to this cement being incorporated in the Works.

B) Water

The water proposed by the Contractor to be used in mixing or curing concrete shall be tested by methods described in Indian Standard or AASHTO Test Method T 26 [or ASTM C1602 / C1602M – 06].

In sampling water for testing, care shall be taken that the containers are clean and that samples are representative.

When comparative tests are made with a water of known satisfactory quality, any indication of unsoundness, marked change in time of setting, or a reduction of more than 10 percent in mortar strength, shall be sufficient cause for rejection of the water under test.

The water shall be tested at a recognized laboratory approved by the Engineer. The test result shall be signed by the laboratory. The water shall be tested before commencement of work or if the source is changed or at any time required by the Engineer. All testing shall be carried out at the Contractor’s expense.

C) Admixtures

Chemical admixtures are not to be used until permitted by the Engineer. In case their use is permitted, the type, amount and method of use of any admixtures proposed by the Contractor shall be submitted to the Engineer for approval. The minimum cement specified shall not be reduced on account of the use of the admixtures.


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The contractor shall provide the following information concerning each admixture to the Engineer: a. Normal chemical dosage and detrimental effects if any of under dosage and over dosage. b. The chemical names of the main ingredients in the admixtures. c. The chloride content, if any, expressed as a percentage by weight of admixture. d. Whether or not the admixture leads to the entrainment of air when used in the manufacturer’s

recommended dosage. e. Where two or more admixtures are proposed to be used in any one mix, the manufacturer’s

written confirmation of their compatibility. 3. In reinforced concrete, the chloride content of any admixture used shall not exceed 2 percent

by weight of the admixtures as determined in accordance with IS: 6925 and the total chloride and sulphate contents in concrete mix shall not exceed 1.15 and 4.0 percent respectively by weight of cement.

The admixtures when used shall conform to IS: 9103. The suitability of all admixtures shall be verified by trial mixes. The addition of calcium chloride to concrete containing embedded metal will not be permitted under any circumstances. Retarding admixtures when used shall be based on ligno-sulphonates with due consideration to clause 5.2 and 5.3 of IS: 7861

D) Aggregates

1) Selection and Approval

From the aggregate materials proposed by the Contractor, samples shall be selected according to Standard Testing Procedure and in the presence of the Engineer. The samples shall be tested at the site laboratory or at an approved testing laboratory for conformance with Section 3.3.1of these Specification.

2) Quality Control

The quality control of the aggregate shall be as directed by Engineer. Grading shall be checked at regular intervals for each supply.

Moisture contents of fine aggregate shall be determined at any time when a change in moisture content is expected.

If the Contractor proposes to change the source of aggregate, the Engineer shall be informed in advance and in no case less than 3 weeks before the new aggregate shall be used.

3.3.3 Composition of Concrete

A) Classes of Concrete

Concrete with cement type as specified for incorporation in the Works shall be of the classes indicated on the Drawings and shall comply with Table 3.3-3.


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Table 3.3-3 Concrete classes

Concrete Class

28 days Characteristic Strength (N/mm2) (15cmx15cm15cm Cube)

Maximum Size of Coarse Aggregate

(mm)

Minimum Cement

Content (Kg/m3)

M7

7

40

20

180

210

M10 10

40

20

210

240

M15 15

40

20

250

280

M20 20

40

20

300

320

M25 25

40

20

340

360

M30 30

40

20

370

400

M35 35

40

20

400

430

B) Proportioning

When designing the concrete mix, the Contractor shall consider the following conditions:

1) Strength

The class of the concrete is to be as shown on the Drawings. The class is the specified characteristic cube strength at 28 days. Concrete mixes shall be designed to comply with Specifications Section 3.3.4.

2) Water/Cement Ratio

The ratio of free water to cement when using saturated surface dry aggregate shall be as low as possible and not exceed 0.50 by weight for all concrete, except for blinding concrete where it shall not exceed 0.6, unless approved by the Engineer.


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For concrete in barriers, edge beams and bridge decks directly exposed to traffic or concrete in pile caps or abutments in contact with the ground, the water cement ratio shall not exceed 0.45, unless approved by the Engineer.

3) Minimum Cement Content

As indicated for the respective class in Table 3.3-3

4) Minimum Filler Content

Filler content (fine aggregate less than 0.25 mm and cement) shall not be less than as follows (except for mass concrete).

Maximum coarse aggregate size (mm) 20 40

Minimum filler content (kg/m3 of concrete) 435 350

5) Coarse Aggregate

The maximum size of coarse aggregate will generally be stated on the Drawings; either 40 mm or 20 mm, in accordance with Table 3.3-1. Grading and quality is to comply with the requirements of Section 3.3.1.

6) Fine Aggregate

The grading and quality is to comply with the requirements of Section 3.3.1.

7) Workability

The concrete shall be of suitable workability to obtain full compaction. Slumps measured in accordance with approved standard procedure shall not exceed 75 mm unless otherwise indicated on the Drawings or approved by the Engineer.

C) Trial Mixes

After the Contractor has received approval for the cement and aggregate to be used, he shall prepare trial mixes with concrete of designed proportions to prove and establish workability, strength, water cement/ratio, surface criteria etc. Methods of transporting fresh concrete and the compaction equipment shall be considered. The trial mixes shall be made and compacted in the presence of the Engineer, using the same type of plant and equipment as will be used for the Works.

From each trial mix, cylinders or cubes shall be made and tested in accordance with Section 3.3.4.

From the same mix as that from which the test specimens are made, the workability of the concrete shall be determined by the slump test. The remainder of the mix shall be cast in a wooden mould and compacted. After 24 hours the sides of the mould shall be struck and the surface examined in order to satisfy the Engineer that an acceptable surface can be obtained with the mix.

The trial mix proportions should be approved if the required strength is obtained from tests carried out in accordance with Section 3.3.4and the consistency and surface is to the satisfaction of the Engineer.


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When a mix has been approved, no variations shall be made in the mix proportions, or in the type, size, grading zone or source, of any of the constituents without the consent of the Engineer, who may require further trial mixes to be made before any such variations are approved.

Until the results of trial mixes for a particular class have been approved by the Engineer, no concrete of the relevant class shall be placed in the Works.

When the Contractor intends to purchase factory-made precast concrete units, trial mixes may be dispensed with provided that evidence is given to satisfy the Engineer that the factory regularly produces concrete which complies with the Specifications. The evidence shall include details of mix proportions, water/cement ratios, slump tests and strengths obtained at 28 days.

3.3.4 Control of Concrete Quality

A) General

The Contractor shall assume the full responsibility for the quality of the concrete conforming to these Specifications and this responsibility shall not be relieved by the testing carried out and approved by the Engineer.

The Contractor shall thus at his own discretion establish additional testing procedures as necessary.

B) Control of Concrete Production

1) Materials

Materials used shall be tested in accordance with the relevant sections of this specification.

2) Plant and Equipment

Batching plants will be tested by the Contractor in a manner approved by the Engineer before any major concrete casting and at any other time if requested by the Engineer. The concreting plant and equipment shall have a capacity for atleast 80m3 of concreting per day.

3) Fresh Concrete

The frequency of slump tests shall be as directed by the Engineer, with at least one test per 25 m3 of concrete.

C) Control of Strength

C.1) Sampling and Testing

The Contractor shall take samples of the concrete for testing. The number, frequency and location shall be decided by the Engineer. A minimum of 3 concrete cubes should be taken for each day’s casting, or for every 15 m3 of concrete cast in large pours. The slump of concrete samples shall be measured.

The procedures for sampling and making cubes and testing them shall be as described in IS: 1199/IS: 516 (or ASTM C873 / C873M - 04e1.)


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C.2) Strength Requirement

The results of the testing shall conform to the strength requirements according to IS: 456 or to any mathematically correct statistical test for each casting section.

C.2.1) General

The characteristic strength of concrete is the 28 days strength below which not more than 5% of the test results may be expected to fall.

C.2.2) Target Mean Strength

The concrete mix should be designed to have a mean strength greater than the required characteristic strength by at least the current margin.

The current margin for each particular type of concrete mix shall be determined; it may be taken as having the smaller of the values given by (1) or (2) below.

C.2.2.1)1.64 times the standard deviation of tests on at least 100 separate batches of concrete of nominally similar proportions of similar materials and produced over a period not exceeding 12 months by the same plant under similar supervision.

C.2.2.2)1.64 times the standard deviation of tests on at least 40 separate batches of concrete of nominally similar proportions of similar materials and produced over a period exceeding 5 days but not exceeding 6 months by the same plant under similar supervision.

Where there are insufficient data to satisfy (1) or (2) above, the margin for the initial mix design should be taken as one-thirds of the characteristic strength for concrete. This margin should be used as the current margin only until sufficient data are available to satisfy (1) or (2) above. However, when the required characteristic strength approaches the maximum possible strength of concrete made with a particular aggregate, a smaller margin may be permitted by the Engineer for the initial mix design.

C.2.3) Testing Plan

Each cube shall be made from a single sample taken from randomly selected batches of concrete.

Compliance with the specified characteristic strength may be assumed if:

1) The average strength determined from any group of four consecutive test cubes exceeds the specified characteristic strength by not less than 0.5 times the current margin, and

2) Each individual test result is greater than 85% of the specified characteristic strength.

The current margin should be taken to be one-thirds (1/3) of the specified characteristic strength for concrete, unless as mentioned above a smaller margin has been established to the satisfaction of the Engineer.

If only one cube result fails to meet the second requirement then that result may be considered to represent only the particular batch of concrete from which that cube was taken provided the average strength of the group satisfies the first requirement.


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If more than one cube in a group fails to meet the second requirement or if the average strength of any group of four consecutive test cubes fail to meet the first requirement then all the concrete in all the batches represented by all such cylinders shall be deemed not to comply with the strength requirements. For the purposes of this sub-Section, the batches of concrete represented by a group of four consecutive test cylinder/cubes shall include the batches from which samples were taken to make the first and the last cubes in the group of four, together with all the intervening batches.

C.2.4) Action to be taken in the event of Non-Compliance with the Testing Plan

When the average strength of four consecutive test cubes fail to meet the first requirement in (F), above, the mix proportions of subsequent batches of concrete should be modified to increase the strength.

The action to be taken in respect of the concrete which is represented by the test- cubes which fail to meet either of the requirements (or not by correct statistical proof can be verified to have the required strength) shall be determined by the Engineer. This may range from qualified acceptance in less severe cases, to rejection and removal in the most severe cases.

The Engineer may also require the Contractor at his own expenses to prove statistically the strength, by boring out cores and testing them according to a program approved by the Engineer. The age of the concrete and degree of hardening at the time of the new testing shall be considered. The equivalent cylinder/cube strength shall comply the minimum characteristic strength or as decided by the Engineer.

D) Control of Hardening

If the Contractor wants to remove forms and scaffolding earlier than specified herein, extra test specimens shall be cast by the Contractor in accordance with the instruction of the Engineer. These specimens shall be tested the day before removal of the form. On the basis of the test results the Engineer shall take the final decision on the time for the removal of forms.

3.4 Construction Methods

3.4.1 General

The Contractor shall in due time and as soon as possible present and discuss his construction methods and work program with the Engineer and shall obtain his approval before commencement of any work.

The Contractor shall maintain an adequate number of trained and experienced supervisors and foremen at the Site to supervise and control the work.

All construction, other than concrete, shall conform to the requirements prescribed in other Sections of the Specifications, for the particular items of work comprising the complete structure.

3.4.2 Care and Storage of Concrete Materials

A) Storage of Cement

All cement shall be stored in suitable weatherproof buildings or silos which will protect the cement from dampness. These buildings or silos shall be placed in locations approved by the Engineer. Provisions for storage shall be ample, and the shipments of cement as received shall be separately


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stored in such manner as to provide easy access for the identification and inspection of each shipment. Storage buildings shall have a capacity for the storage of a sufficient quantity of cement to allow sampling at least 14 days before the cement is to be used. Cement shall meet the test requirements at any time and any cement stored for an elongated time shall be checked and tested before use regardless of whether it has previously been tested.

B) Storage of Aggregates

Aggregates shall be so stored as to prevent the inclusion of foreign material. Aggregates shall not be placed upon the finished roadbed. Aggregates of different sizes and kinds shall be placed in different stockpiles. Stockpiles of blended coarse aggregates shall be built up in successive horizontal layers not more than 1 meter thick. Each layer shall be completed before the next is started. Should segregation occur, the aggregates shall be recombined to conform to the grading requirement.

Washed aggregates and aggregates produced or manipulated by methods which involve the use of water shall be allowed to drain at least 12 hours before use.

3.4.3 Preparations before Casting

Before any major casting, the Contractor shall prepare a complete “casting program” describing staff and labor, consumption of materials, plant, tools and equipment, reserves of materials, standby plant and equipment, proposed means of handling and placing the concrete, quality controls etc.

No concrete shall be mixed and placed until the Contractor’s casting program has been approved in writing by the Engineer.

Equipment and tools necessary for handling materials and performing the work, and satisfactory to the Engineer as to design, capacity, and mechanical condition, shall be at the site of the work before casting is started.

If any equipment is not maintained in full working order, or if the equipment as used by the Contractor proves inadequate to obtain the result prescribed, such equipment shall be repaired or other suitable equipment substituted or added at the discretion of the Engineer.

3.4.4 Measuring Materials

All material in the mix shall be proportioned by weight or volume, subject to the approval of the Engineer.

When volume batching is proposed by the Contractor, the exact proportions must be converted from trial mix weights to volumes, from bulk densities determined in the laboratory. Written approval from the Engineer is required.

3.4.5 Mixing Concrete

A) General

All concrete shall be mixed in batch mixers, either at the site of construction, at a central plant, or in transit. Each mixer shall have attached to it in a prominent place, a manufacturer’s plate showing the capacity of the drum in terms of mixed concrete and the speed of rotation of the mixing drum.

B) Mixers at Local Site of Construction


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Mixers at local sites shall be approved drum-type capable of combining the aggregate, cement, and water into a thoroughly mixed and uniform mass within the specified mixing period and of discharging the mixture without segregation. The mixer shall be equipped with a suitable charging hopper, water storage and a water measuring device, accurate within 1%. Controls shall be so arranged that the water can be applied only while the mixer is being charged. Suitable equipment for discharging the concrete shall be provided. The mixer shall be cleaned at suitable intervals. The pickup and throw-over blades in the drum shall be replaced when they have lost 10% of their depth.

The mixer shall be operated at a drum speed of between 15 and 20 revolutions per minute. The batched materials shall be so charged into the drum that a portion of the water shall enter in advance of the cement and aggregates and the water shall continue to flow into the drum for a minimum time of 5 seconds after all the cement and aggregates are in the drum. Mixing time shall be measured from the time all materials except water are in the drum and shall, in the case of mixers having a capacity of 1 cubic Meter or less, not be less than 50 seconds nor more than 70 seconds. In the case of dual drum mixers, the mixing time shall not include transfer time. The contents of an individual mixer drum shall be removed before a succeeding batch is emptied therein. Any concrete mixed less than the specified minimum time shall be discarded and disposed of by the Contractor at his own expense.

The volume of concrete mixed per batch shall not exceed the mixer’s nominal capacity in cubic feet or cubic meters as shown on the manufacturer’s guaranteed capacity standard rating plate on the mixer; except that an overload up to 20% of the mixers nominal capacity may be permitted provided concrete test data for strength, segregation and uniform consistency are satisfactory, and provided no spillage of concrete takes place.

Re-tempering concrete by adding water or by other means shall not be permitted. Concrete which is not of the required consistency at the time of placement shall not be used and shall be discarded and disposed of by the Contractor at his own expense.

C) Central Plant Mixers

These mixers shall be of approved drum type capable of combining the aggregate, cement and water into a thoroughly mixed and uniform mass within the specified mixing period and of discharging the mixture without segregation. Central plant mixers shall be equipped with an acceptable timing device that will not permit the batch to be discharged until the specified mixing time has elapsed. The water system for a central mixer shall be either a calibrated measuring tank or a meter and shall not necessarily be an integral part of the mixer.

The mixers shall be cleaned at suitable intervals. They shall be examined daily for changes in interior condition. The pick up and throw-over blades in the drum shall be replaced when they have lost 10% of their depth.

In addition to the requirements for mixers at local sites detailed above, central plant mixers which have a capacity of between 2 and 5 cubic meters, or greater than 5 cubic meters, should have a minimum mixing time of 90 and 120 seconds respectively, provided tests indicate that the concrete produced is equivalent in strength and uniformity to that attained as stated in the preceding paragraphs.

Mixed concrete shall be transported from the central mixing plant to the site of work in agitator trucks or, upon written permission of the Engineer, in non-agitator trucks. Delivery of concrete shall be so regulated that placing is at a continuous rate unless delayed by the placing operations. The intervals


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between deliveries of batches shall not be so great as to allow the concrete in place to harden partially, and in no case shall such an interval exceed 30 minutes.

D) Agitator Trucks

Unless otherwise permitted in writing by the Engineer, agitator trucks shall have watertight revolving drums suitably mounted and shall be capable of transporting and discharging the concrete without segregation. The agitating speed of the drum shall not be less than two or more than six revolutions per minute. The volume of mixed concrete permitted in the drum shall not exceed the manufacturer’s rating nor exceed 80% the gross volume of the drum.

Upon approval by the Engineer, open-top, revolving-blade truck mixers may be used in lieu of agitating trucks for transportation of central plant mixed concrete.

Gross volume of agitator bodies expressed in cubic feet or cubic Meters shall be supplied by the mixer manufacturer. The interval between introduction of water into the mixer drum and final discharge of the concrete from the agitator shall not exceed 45 minutes. During this interval the mix shall be agitated continuously.

E) Non-Agitator Trucks

Bodies of non-agitating equipment shall be smooth, water-tight metal containers equipped with gates that will permit control of the discharge of the concrete. Covers shall be provided when needed for protection against the weather.

The non-agitating equipment shall permit delivery of the concrete to the site of the work in a thoroughly mixed and uniform mass with a satisfactory degree of discharge.

Uniformity shall be satisfactory if samples from the one-quarter and three quarter points of the load do not differ by more than 30 mm in slump. Discharge of concrete shall be completed within 30 minutes after the introduction of the mixing water to the cement and aggregate.

F) Truck or Transit Mixers

These shall be equipped with electrically actuated counters by which the number of revolutions of the drum or blades may readily be verified and the counters shall be actuated at the commencement of mixing operations at designated mixing speeds. The mixer when loaded shall not be filled to more than 60% of the drum gross volume. The mixer shall be capable of combining the ingredients of the concrete into a thoroughly mixed and uniform mass and of discharging the concrete with a satisfactory degree of uniformity.

Except when intended for use exclusively as agitators, truck mixers shall be provided with a water measuring device to measure accurately the quantity of water for each batch. The delivered amount of water shall be within plus or minus 1% of the indicated amount.

Truck mixers may be used for complete mixing at the batch plant and as truck agitators for delivery of concrete to job sites, or they may be used for complete mixing of the concrete at the job site. They shall either be a closed watertight revolving drum or an open top revolving blade or paddle type.

The amount of mixing shall be designated in number of revolutions of the mixer drum. When a truck mixer is used for complete mixing, each batch of concrete shall be mixed for between 70 and 100 revolutions of the drum or blades at the rate of rotation designated by the manufacturer of the


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equipment as the “mixing speed”. Such designation shall appear on a metal plate attached to the mixer. If the batch is at least 0.5 cubic meters less than guaranteed capacity, the number of revolutions at mixing speed may be reduced to not less than 50. Mixing in excess of 100 revolutions shall be at the agitating speed. All materials, including the mixing water, shall be in the mixer drum before actuating the revolution counter which will indicate the number of revolutions of the drum or blades.

When wash water (flush water) is used as a portion of the mixing water for the succeeding batch, it shall be accurately measured and taken into account in determining the amount of additional mixing water required. When wash water is carried on the truck mixer, it shall be carried in a compartment separate from the one used for carrying or measuring the mixing water. The Engineer will specify the amount of wash or flush water, when permitted, any may specify a “dry” drum if wash water is used without measurement or without supervision.

When a truck is used for complete mixing at the batch plant, mixing operations shall begin within 30 minutes after the cement has been added to the aggregate. After mixing, the truck mixer shall be used as an agitator, when transporting concrete, at the speed designated by the manufacturer of the equipment as agitating speed. Concrete discharge shall be completed within 45 minutes after the addition of the cement to the aggregates. Each batch of concrete delivered at the job site shall be accompanied by a time slip issued at the batching plant, bearing the time of departure there from. When the truck mixer is used for the complete mixing of the concrete at the job site, the mixing operation shall begin within 30 minutes after the cement has been added to the aggregates.

The rate of discharge of the plastic concrete from the mixer drum shall be controlled by the speed of rotation of the drum in the discharge direction with the discharge gate fully open.

3.4.6 Handling and Placing Concrete

The temperature of concrete at the time of placing shall not be below 5°C or above 35°C.

In preparation for the placing of concrete all sawdust, chips and other construction debris and extraneous matter shall be removed from the interior of forms. Struts, stays and braces, serving temporarily to hold the forms in correct shape and alignment, pending the placing of concrete at their locations, shall be removed when the concrete placing has reached an elevation rendering their service unnecessary. These temporary members shall be entirely removed from the forms and not buried in the concrete.

Concrete must reach its final position in the forms within 20 minutes of the completion of mixing, or as directed by the Engineer.

Concrete shall be placed so as to avoid segregation of the materials and the displacement of the reinforcement. The use of long troughs, chutes and pipes for conveying concrete from the mixer to the forms shall be permitted only on written authorization of the Engineer. In case an inferior quality of concrete is produced by the use of such conveyors, the Engineer may order discontinuance of their use and the institution of a satisfactory method of placing.

Open troughs and chutes shall be of metal or metal lined. Where long steep slopes are required, the chutes shall be equipped with baffles or be in short lengths that reverse the direction of movement.

All chutes, troughs and pipes shall be kept clean and free from coatings of hardened concrete by thoroughly flushing with water after each run. Water used for flushing shall be discharged clear of the structure.


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When placing operations would involve dropping the concrete more than 1 .5 m, it shall be deposited through sheet metal or other approved pipes. As far as practicable, the pipes shall be kept full of concrete during placing and their lower ends shall be kept buried in the newly placed concrete. After initial set of the concrete, the forms shall not be jarred and no strain shall be placed on the ends of reinforcement bars which project.

Concrete, during and immediately after depositing, shall be thoroughly compacted. The compaction shall be done by mechanical vibration subject to the following provisions:

1) The vibration shall be internal unless special authorization of other methods is given by the Engineer or as provided herein.

2) Vibrators shall be of a type and design approved by the Engineer. They shall be capable of transmitting vibration to the concrete at frequencies of not less than 4,500 impulses per minute.

3) The intensity of vibration shall be such as to visibly affect a mass of concrete of 20 mm slump over a radius of at least 450 mm.

4) The Contractor shall provide a sufficient number of vibrators to properly compact each batch immediately after it is placed in the forms.

5) Vibrators shall be manipulated to thoroughly work the concrete around the reinforcement and embedded fixtures, and into the corners and angles of the forms.

Vibration shall be applied at the point of deposit and in the area of freshly deposited concrete. The vibrators shall be inserted and withdrawn from the concrete slowly. The vibration shall be of sufficient duration and intensity to thoroughly compact the concrete, but shall not be continued so as to cause segregation. Vibration shall not be continued at any one point to the extent that localized areas of grout are formed.

Application of vibrators shall be at points uniformly spaced and not further apart than twice the radius over which the vibration is visibly effective.

6) Vibration shall not be applied directly or through the reinforcement to sections or layers of concrete which have hardened to the degree that the concrete ceases to be plastic under vibration. It shall not be used to make concrete flow in the forms over distances so great as to cause segregation, and vibrators shall not be used to transport concrete in the forms.

7) Vibration shall be supplemented by such spading as is necessary to ensure smooth surfaces and dense concrete along form surfaces and in corners and locations impossible to reach with the vibrators.

8) The provisions of this Section shall also apply to precast piling, concrete cribbing and other precast members except that, if approved by the Engineer, the manufacturer’s methods of vibration may be used.

Concrete shall be placed in horizontal layers not more than 600 mm thick except as hereinafter provided. When less than a complete layer is placed in one operation, it shall be terminated in a vertical bulkhead. Each layer shall be placed and compacted before the preceding batch has taken initial set to prevent injury to the green concrete and avoid surfaces of separation between the batches. Each layer shall be compacted so as to avoid the formation of a construction joint with a preceding layer which has not taken initial set.


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When the placing of concrete is temporarily discontinued, the concrete, after becoming firm enough to retain its form, shall be cleaned of laitance and other objectionable material to a sufficient depth to expose sound concrete. To avoid visible joints as far as possible upon exposed faces, the top surface of the concrete adjacent to the forms shall be smoothed with a trowel. Where a “feather edge” might be produced at a construction joint, as in the sloped top surface of a wing wall, an inset form shall be used to produce a blocked out portion in the preceding layer which shall produce an edge thickness of not less than 150 mm in the succeeding layer. Work shall not be discontinued within 450 mm of the top of any face, unless provision has been made for a coping less than 450 mm thick, in which case, if permitted by the Engineer, a construction joint may be made at the underside of the coping.

Immediately following the discontinuance of placing concrete all accumulations of mortar splashed upon the reinforcement steel and the surfaces of forms shall be removed. Dried mortar chips and dust shall not be puddle into the unset concrete. If the accumulations are not removed prior to the concrete becoming set, care shall be exercised not to injure or break the concrete-steel bond at and near the surface of the concrete, while cleaning the reinforcement steel.

For simple spans, concrete shall preferably be deposited by beginning at the centre of the span and working from the centre toward the ends. Concrete in girders shall be deposited uniformly for the full length of the girder and brought up evenly in horizontal layers. For continuous spans, the concrete placing sequence shall be as shown on the plans or agreed on by the Engineer.

Concrete in slab and girder haunches less than 1 .0 Meter in height shall be placed at the same time as that in the girder stem.

Concrete in slab spans shall be placed in one continuous operation for each span unless otherwise provided.

Concrete in T-beam or deck girder spans may be placed in one continuous operation if permitted by the Engineer.

Concrete in columns and pier shafts shall be placed in one continuous operation, unless otherwise directed.

Unless otherwise permitted by the Engineer, no concrete shall be placed in the superstructure until the column forms have been stripped sufficiently to determine the character of the concrete in the columns. The load of the superstructure shall not be applied to the supporting structures until they have been in place at least 14 days, unless otherwise permitted by the Engineer.

Pneumatic placing of concrete shall be permitted only if authorized by the Engineer. The equipment shall be so arranged that vibration does not damage freshly placed concrete.

Where concrete is conveyed and placed by pneumatic means the equipment shall be suitable in kind and adequate in capacity for the work. The machine shall be located as close as practicable to the place of deposit. The position of the discharge end of the line shall not be more than 3 Meters from the point of deposit. The discharge lines shall be horizontal or inclined upwards from the machine. At the conclusion of placement the entire equipment shall be thoroughly cleaned.

Placement of concrete by pumping shall be permitted only if authorized by the Engineer. The equipment shall be so arranged that vibrations do not damage freshly placed concrete. Where concrete is conveyed and placed by mechanically applied pressure, the equipment shall be suitable in kind and adequate in capacity for the work. The operation of the pump shall be such that a continuous stream of concrete without air pockets is produced. When pumping is completed, the concrete


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remaining in the pipeline, if it is to be used, shall be ejected in such a manner that there is not contamination of the concrete or separation of the ingredients. After this operation, the entire equipment shall be thoroughly cleaned.

3.4.7 Perforations and Embedment of Special Devices

The Contractor is responsible for determining in advance of making any concrete pours, all requirements for perforation of concrete sections or embedment therein of special devices of other trades, such as conduits, pipes, weep holes, drainage pipes, fastenings, etc. Any concrete poured without prior provision having been made, shall be subject to correction at the Contractor’s expense.

Special devices to be embedded:

1. Expansion joints

2. Drain outlets including fixing bolts for down pipes

3. Bolts and inserts for sign posts

4. Bolts and inserts for various purposes regarding inspection and maintenance as directed by the Engineer

5. Other devices not mentioned above shall be shown on the Drawings, or directed by the Engineer.

3.4.8 Finishing Concrete Surfaces

One of the following types of finishing shall be applied to concrete surfaces:

Type A - Concrete Decks

Immediately after placing concrete, concrete decks shall be struck off using templates to provide proper crowns and shall be finished smooth to the correct levels. Finish shall be slightly but uniformly roughened by brushing. The finished surface shall not vary more than 10 mm from a 3 Meter straight edge placed in any direction on the roadway. Deviation from the grade line shall not be more than + 30 mm in any 20 Meter length.

Type B - Kerb and Sidewalk Surface

Exposed faces of kerbs and sidewalks shall be finished to true lines and grades. The kerb surface shall be wood floated to a smooth but not slippery finish. Sidewalk surfaces shall be slightly but uniformly roughened by brushing.

Type C - Ordinary Finish

An ordinary finish is defined as the finish left on a surface after the removal of the forms when all holes left by form ties have been filled, and any minor surface defects have been repaired. The surface shall be true and even, free from depressions or projections.

The concrete in bridge seats, caps, and tops of walls shall be struck off with a straight edge and floated to true grade. Under no circumstances shall the use of mortar topping for concrete surfaces be permitted.

Type D - Rubbed Finish


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After the removal of forms the rubbing of concrete shall be started as soon as its condition permits. Immediately before starting this work the concrete shall be kept thoroughly saturated with water for a minimum period of three hours. Sufficient time shall have elapsed before the wetting down to allow the mortar used in patching to have thoroughly set. A medium coarse carborundum stone shall be used for rubbing a small amount of mortar on the face. The mortar used shall be composed of cement and fine aggregate mixed in the same proportions as that used in the concrete being finished. Rubbing shall be continued until all form marks, projections, and irregularities have been removed, all voids filled, and a uniform surface has been obtained. The paste produced by this rubbing shall be left in place at this time. The final finish shall be obtained by rubbing with a fine carborundum stone and water until the entire surface is of a smooth texture and uniform color.

After the final rubbing has been completed and the surface has dried, burlap shall be used to remove loose powder. The final surface shall be free from unsound patches, paste, powder and objectionable marks.

Type E – Bush hammer Finish

Bush hammering shall be carried out by treating the surface with an approved heavy duty power hammer fitted with a multi-point tool which shall be operated over the surface to remove 5 to 6 mm of concrete paste and expose maximum areas of coarse aggregate.

Aggregate left embedded shall not be fractured or loose. 25 mm wide bands at all corners and arises shall be left as cast. The finish surface shall be even and of uniform appearance and shall be washed with water upon completion.

Type F - Ribbed Finish

Ribs shall be vertical and to the dimensions shown on the Drawings. The direction of the grain of the timber forming the ribs shall be vertical.

3.4.9 Construction Joints

A) General

Construction joints shall be made only where located on the plans or shown in the pouring schedule, unless otherwise approved by the Engineer.

If not detailed on the plans, or in the case of emergency, construction joints shall be placed as directed by the Engineer. Shear keys or inclined reinforcement shall be used where necessary to transmit shear or bond the two sections together.

B) Bonding

Before depositing new concrete on or against concrete which has hardened, the forms shall be re-tightened. The surface of the hardened concrete shall be roughened as required by the Engineer, in a manner that does not leave loosened particles of aggregate or damaged concrete at the surface. It shall be thoroughly cleaned of foreign matter and laitance, and saturated with water. To ensure an excess of mortar at the juncture of the hardened and the newly deposited concrete, the cleaned and saturated surfaces, including vertical and inclined surfaces, shall first be thoroughly covered with a thin coating of mortar or neat cement grout against which the new concrete shall be placed before the grout has attained its initial set.


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The placing of concrete shall be carried continuously from joint to joint. The face edges of all joints which are exposed to view shall be carefully finished true to line and elevation.

3.4.10 Curing Concrete

All concrete surfaces shall be kept thoroughly wet for at least 7 days after placing. Bridge deck and sidewalk slabs shall be covered with wet hessian immediately after final finishing of the surface. This material shall remain in place for the full curing period or may be removed and replaced with sand when the concrete has hardened sufficiently to prevent marking. In both cases the materials shall be kept thoroughly wet for the entire curing period. All other surfaces if not protected by forms, shall be kept thoroughly wet, either by sprinkling or by the use of wet burlap until the end of the curing period. The wood forms are allowed to remain in place during the curing period, but they shall be kept moist at all times to prevent openings at joints.

After a period of 7 days, the concrete shall be watered daily at certain intervals approved by the Engineer to avoid drying out of the surface. This shall take place during the following 2 weeks. The water used shall be the same as used in concrete mixes unless otherwise approved by the Engineer.

Any proposal from the Contractor for the use of liquid membrane curing compound shall be subject to the approval of the Engineer.

3.4.11 Removal of Scaffolding and Formwork

Forms and scaffolding shall not be removed without the approval of the Engineer. The Engineer’s approval shall not relieve the Contractor of his Contract responsibilities. Any kentledge blocks and bracing shall be removed at the same time as the forms and in no case shall any portion of the wood forms be left in the concrete.

Forms used on exposed vertical faces shall remain in place for periods which shall be determined by the Engineer and normally not less than 3 days.

Supporting scaffolding and forms under slabs, beams and girders shall normally remain in place until the full required strength of the concrete has been obtained. If a shorter period is requested, this may be permitted by the Engineer. In such case, special test specimens shall be cast to monitor the hardening.

All structures shall be fully stripped before adjacent structures are cast.

3.4.12 Repair of Concrete

As soon as the form has been stripped, the Contractor shall advise the Engineer who shall inspect the concrete before any improvement of the surface takes place.

All wire or metal devices used for securing the formwork which project from or appear on the surface of the finished concrete shall be removed or cut back to at least a depth equal to the required reinforcement cover. All holes and pockets so formed shall be filled with cement mortar mixed in the same proportions as the fine aggregate to cement of the concrete mix used for that particular section of the structure, after the surface to be patched has been thoroughly cleaned and wetted to receive the patch.


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Excessive honeycombing shall be sufficient to cause rejection of portions of the structure containing this honeycombing. The Contractor, on receipt of written orders from the Engineer, shall remove and rebuild such portions of the structure at his own expense.

Smaller honeycombing and other defects can be repaired if permitted by the Engineer. Structural, maintenance and aesthetical points of view shall be taken into consideration before such approval, if any, may be given. The method of repair shall be approved by the Engineer and an extension of period for a certain part of the performance security may be required.

3.4.13 Depositing Concrete under Water

Concrete shall not be deposited in water except with the approval of the Engineer and under his immediate supervision; and in this case the method of placing shall be as defined in this Section.

Concrete placed under water shall be carefully placed in a compact mass, in its final position, by means of a tremie tube and shall not be disturbed after being deposited. Special care must be exercised to maintain still water at the point of deposit. Concrete shall not be placed in running water. The method of depositing concrete shall be so regulated as to produce approximately horizontal surfaces.

Concrete seals shall be placed in one continuous operation. When a tremie tube or pipe is used, it shall consist of a tube or pipe not less than 150 mm in diameter. All joints in the tube shall be watertight. The means of supporting the tremie tube shall be such as to permit free movement of the discharge end over the entire top of the concrete and to permit its being lowered rapidly when necessary to choke off or retard the flow. The tremie tube shall be filled by a method that prevents washing of the concrete. The discharge end shall be completely submerged in concrete at all times and the tremie tube shall be kept full. Concrete slump shall not be less than 150 mm.

Dewatering shall proceed only when the concrete seal is considered strong enough to withstand any pressure to be exerted upon it. This time shall be decided by the Engineer.

All laitance or other unsatisfactory material shall be removed from the exposed surface by scraping, jetting, chipping or other means, which do not injure the seal unduly.

3.4.14 Factory Made Precast Concrete Elements

Any supplier of precast concrete elements shall be approved in writing by the Engineer. Such approval can be withdrawn at any time.

Concrete work in precast concrete elements shall fully conform to all relevant Sections of these Specifications.

The supplier shall maintain laboratory facilities of the same standard as the site laboratory.

Unless otherwise approved by the Engineer, precast concrete members shall not be moved from the casting position until the concrete has attained a compressive strength of80% of the specified 28 day strength, nor transported until it has developed strength of90% of the specified 28 day strength.

Extreme care shall be exercised in handling and moving precast concrete members. Precast girders and slabs shall be transported in an upright position. Shock shall be avoided and the points of support and directions of the reactions with respect to the member shall be approximately the same during transportation and storage as when the member is in its final position. If the Contractor deems it


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expedient to transport or store precast units in other than this position, this shall be at the Contractor’s risk, after notifying the Engineer of his intention to do so. Any rejected unit shall be replaced at the Contractor’s expense by an acceptable unit.

Proposed details on the handling and transportation of precast concrete members shall be submitted in writing by the Contractor, to the Engineer, for his approval.

Each precast member is to be uniquely and permanently marked so as to show its type, date of casting and any other information required by the Engineer.

3.4.15 Control of Heat in Structures

In structures of major dimensions i.e., pile caps, etc. the heat deriving from the hardening of the concrete shall be controlled by the Contractor. Temperature gradients introducing risk of cracking shall not occur and the temperature shall not exceed 70°C.

The Contractor shall submit timely proposals for avoiding excessive heat generation, such as the cooling of aggregates before mixing, to the Engineer for approval.

3.4.16 Loading

No superstructure load shall be placed upon finished bents, piers, or abutments until the Engineer so directs but in no case shall any load of any kind be placed until the concrete has completed curing.

The Contractor shall not place any temporary loads on deck slabs unless allowed by the Engineer in writing. Bridge deck slabs shall be opened to traffic only when so directed by the Engineer and generally not sooner than 28 days after the placing of the concrete has been completed.

3.4.17 Backfill to Structures

All spaces which have been excavated and the volumes of which are not occupied by the concrete structure shall be backfilled and compacted with acceptable material in accordance with the provisions of relevant specification and as directed by the Engineer.

3.4.18 Cleaning Up

Upon completion of a structure and before final acceptance, the Contractor shall remove all forms and scaffolding etc. down to 0.5 Meters below the finished ground line. Excavated, or useless materials, rubbish etc. shall be removed from the Site and the Site shall be left in a neat and tidy condition satisfactory to the Engineer.

3.5 Measurement

Concrete shall be measured by the number of cubic Meters of Class indicated on the Drawings complete in place and accepted by the Engineer. In computing quantities, the dimensions used shall be those shown on the Drawings. No deduction from the measured quantity shall be made for drainage, pipes less than 300 mm in diameter, conduits, chamfers, reinforcement bars, expansion joints, water stops or pile heads embedded in concrete.

Reinforcing steel shall be measured for payment as described in Section 3.8.


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3.6 Payment

The concrete of grades shown on the Drawings and measured as provided in Section 3.5shall be paid for at the Contract unit prices per cubic Meter. The Contractor’s rates shall include materials, mixing, transporting, placing and compacting the concrete. The rates shall also include all trial mixes, all conformance tests, all concrete finishings, the supply, placing and building in of weep pipes or pipe sleeves, forming construction joints, forming holes or pockets not exceeding 0.15 m3 each.

Payment for precast units shall include all concrete, formwork, finishing, transport and erection and where applicable any bolts, bedding or other devices necessary to fix them in their permanent position.

3.7 Formwork and Scaffolding

3.7.1 Scaffolding (Falsework)

Details, plans and structural calculations for scaffolding shall be submitted by the Contractor to the Engineer for approval, but in no case shall the Engineer’s approval relieve the Contractor of his contract responsibilities. All scaffolding shall be designed and constructed by the Contractor to provide the necessary rigidity and to support dead and live loads without deflection or deformation. The Engineer may require the Contractor to employ screw jacks or hardwood wedges to take up any settlement in scaffolding and formwork, either before or during the placing of concrete.

Tests may be required by the Engineer of materials proposed by the Contractor for scaffolding. Test loadings of the completed scaffolding may also be required for the determination of flexibility and strength. All expenses associated with testing shall be borne by the Contractor.

Scaffolding which cannot be founded on a satisfactory footing shall be supported on piles, which shall be spaced, driven and removed in a manner approved by the Engineer. When the Contractor wishes to support scaffolding on existing structures, he shall submit his proposals in due time to the Engineer, in writing, including loads from the scaffolding. The Engineer will consider the proposals and respond in writing.

Scaffolding shall be set to give the finished structure a camber, if indicated on the Drawings or specified by the Engineer.

Scaffolding shall remain in place for periods which shall be determined by the Engineer.

The formwork shall be properly designed for the self-weight, weight of reinforcement, weight of fresh concrete, various live loads imposed during the construction process (such as workmen and equipment). Dumping of concrete, movement of construction equipment and action of the wind may produce lateral forces which must be resisted by the form work to prevent lateral failure for which suitable horizontal as well as diagonal bracings shall be provided. The permissible stresses in bending, buckling load of props, permissible deflection of shuttering should not be exceeded.

In case the height of centering exceeds 3.50 Meters, the props may be provided in multi-stages.

Before the concreting is started, the props and wedges shall be thoroughly checked to see that these are intact, and take suitable action in case these are loose. While the concreting is in progress, at least one carpenter shall be readily available at the site. The carpenter shall keep a constant watch on


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the props and take immediate remedial measures, as soon as any of these get loosened. Care shall be taken that props and wedges do not get loose for a minimum period specified in Table 3.7-1.

3.7.2 Formwork

Formwork shall include all temporary or permanent moulds for forming the concrete. Formwork shall be of wood, metal or other approved materials and shall be built mortar tight and rigid enough to maintain the concrete in position during placing, compacting, setting and hardening.

Formwork for exposed surfaces (“wrought form”) shall be made of dressed lumber of uniform thickness with or without a form liner of an approved type or shall be of metal sufficiently rigid in itself with no surface blemishes that will impair the quality of the concrete surface finish. No rusty or bent metal forms shall be used. Exposed concrete arises shall be provided with formed chamfers, as indicated on the Drawings or instructed by the Engineer.

Rough lumber may be used for surfaces that will not be exposed in the finished structure (“rough form”).

All lumber shall be sound, free from warps and twists, sap, shakes, large or loose knots, wavy edge or other defects affecting the strength or appearance of the finished structure.

All forms shall be set and maintained true to the line designated until the concrete is sufficiently hardened. Forms shall remain in place for periods, which shall be determined by the Engineer. When forms appear to be unsatisfactory in any way, either before or during the placing of concrete, the Engineer may order the work to be stopped until the defects are corrected.

If requested, the Contractor shall submit to the Engineer working drawings of the forms and also, if requested, calculations to verify the rigidity and strength of the forms.

The shape, strength, rigidity, water tightness and surface smoothness of reused formwork shall be maintained at all times. Any warped or bulged lumber must be re-sized before being reused. Formwork that is unsatisfactory in any respect shall not be reused.

Metal ties or anchorages within the form shall be so constructed as to permit their removal to a depth of at least 50 mm from the face without injury to the concrete. All fittings for metal ties shall be of such design that, upon their removal, the cavities which are left will be of the smallest possible size. The cavities shall be filled with cement mortar and the surface left sound, smooth, even and uniform in color.

Formwork shall be so constructed that easy cleaning out of any extraneous material inside the formwork can be achieved without disturbing formwork already checked and approved by the Engineer.

Formwork shall be treated with approved non-staining oil or saturated with water, to facilitate formwork removal. The Engineer may require trials to be carried out before approval is given for the use of a particular type of oil, to ascertain that the oil proposed by the Contractor does not discolor or injure the finished concrete face in any way.

Before placing any concrete, all shavings, loose binding wires, soil, rubbish and all foreign matter shall be removed from the formwork and the formwork shall be carefully and thoroughly washed with water. If not indicated otherwise, the following tolerances of the finished concrete structures shall apply:


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Foundations: horizontally ±30 mm; vertically ±20 mm

Piers: Horizontally±20 mm, vertically~ 10mm, inclination 1:400

Dimensions of other structural members: + 10 mm, -5 mm

Edge beams and parapets shall be made to such accuracy that no deviations from the correct alignment are visible.

The cross sectional areas of the superstructure of bridges shall in no place deviate more than 3% from the theoretically correct cross sectional areas.

Anchors for bearings, expansion joints, railings, etc. shall be placed within the tolerances indicated on the Drawings or specified by the Engineer.

3.7.3 Surface Treatment for Shuttering

The surfaces of timber shuttering that would come in contact with concrete shall be well wetted and coated with soap solution, raw linseed oil or form oil of approved manufacture, to prevent adhesion of concrete to form work. Use of polythene sheets shall not be permitted. Soap solution, for the purpose shall be prepared by dissolving yellow soap in water to get the consistency of paint. Inside surfaces of forms shall be thoroughly cleaned before application of any of the materials mentioned above. Release agents shall be applied strictly in accordance with the manufacturers’ instructions and shall not be allowed to come in contact with any reinforcement. Re-use of the shuttering shall be permitted only after the inside surface has been thoroughly cleaned in the manner described above.

Contractor shall give the Engineer due notice before placing any concrete in the forms to permit him to inspect and accept the form work as to its strength, alignment and general fitness, but such inspection shall not relieve the contractor of his responsibility for safety of workman, machinery, materials and for results obtained.

3.7.4 Camber

Cambers both along and across the bridge shall be provided as per the lines and levels shown in the design drawings or as directed by the Engineer. The scaffold and the formwork shall be so assembled as to provide for such camber. For cantilevers, the camber at free end shall be 1/50th of the projected length or as directed by the Engineer.

3.7.5 Approval of Scaffolding and Formwork

If plans and calculations of scaffolding and formwork are sought by the Engineer, no construction of such scaffolding and formwork shall take place before approval by the Engineer, in writing. Such approval shall not relieve the Contractor of his responsibilities under the Contract for the adequacy of scaffolding and formwork.

The Engineer shall have reasonable time for his examination of the Contractor’s plans and calculations, especially if scaffolding is introducing temporary loading on new structures. The Contractor shall not be granted time extension due to awaiting such approval.

The Engineer shall inspect all formwork and scaffolding and no concrete shall be placed until the Engineer’s approval has been given. Such approval shall not relieve the Contractor of any of his responsibilities under the Contract for the successful completion of the structure.


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3.7.6 Special Formwork

For special type of work-locations like tall structures etc. use of special types of formwork like moving or climbing forms shall be permitted. The details of such formworks along with the sequence of working shall be approved by the Engineer before their erection.

3.7.7 Removal of Form Work

No formwork or any part thereof shall be removed without prior approval of the Engineer. The formwork shall be so removed as not to cause any damage to concrete due to shock or vibration. In a slab and beam construction, sides of beam shall be stripped first, then the under sides of slab and lastly the underside of the beam. Formwork must be so designed that they can be stripped in the order required i.e.

(a) Shutters to vertical (non load bearing) faces e.g. column boxes, beam sides, wall forms,

(b) Shutters forming soffits to slabs, horizontal and inclined which carry only light load, e.g. slabs, roofs, floors and canopies etc.

(c) Soffit shutters carrying heavy load e.g. beam and girder bottoms.

The whole of the formwork should be planned and a definite scheme of operation worked out. In no circumstances should forms be struck until the concrete reaches strength of at least twice the stress to which the concrete may be subjected at the time of striking. Where possible the formwork should be left longer as it would assist curing. Forms should be eased carefully in order to prevent the load being suddenly transferred to concrete. The period that shall elapse after the concrete has been laid, before easing and removal of centering and shuttering is undertaken shall be as given in Table 3.7-1below:

Table 3.7-1 Removal of Form Work

Type of formwork

Minimum period before striking formwork

Vertical formwork of Column, Wall and beams

16 – 24 h

Soffit formwork to slabs (props to be re-fixed immediately after removal of formwork)

3 days

Soffit formwork to beams (props to be re-fixed immediately after removal of formwork)

7 days

Props to deck slabs spanning upto 4.5 m

7 days

Props to deck slabs spanning over 4.5 m

14 days

Props to beams spanning upto 6m

14 days

Props to beams and arches spanning over 6 m

21 days

Note 1: In case of cantilever slabs and beams, the centering shall remain till structures for counter acting or bearing down have been erected and have attained sufficient strength.


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Note 2: Proper precautions should be taken to allow for the decrease in the rate of hardening that occurs with all cements in cold weather.

Note 3: Work damaged through premature or careless removal of forms shall be reconstructed.

3.7.8 Measurements

The formwork shall be paid for separately. Measurement shall be taken of the area of shuttering in contact with the concrete surface.

Dimensions of formwork shall be measured correct to 10mm. The measurements shall be taken separately under each of the items mentioned in the Pay Item.

No deductions from the shuttering due to the openings/ obstructions shall be made if area of such openings/obstructions does not exceed 0.1sq.m. Nothing extra shall be paid for forming such openings.

3.7.9 Payment

The rate of formwork includes the cost of planning and design of a safe scaffold system, material, erection, centering & propping, shuttering and formwork and other materials, tools and plant, labor required for all the operations described in this section including properly supporting the members as required until the concrete is cured, set and hardened as required. No separate payment shall be made for items such as form release agent, connections, ties, provisions for openings and other items required for the completion of the work unless specified otherwise.

3.8 REINFORCEMENT

3.8.1 Description

This work shall consist of furnishing and placing bars of the grade, type and size in accordance with this specification and the BoQ and in conformity with the requirements shown in the Drawings.

3.8.2 Materials

Bar Reinforcement

All high yield steel bars shall be deformed bars with a yield stress not less than 500 N/mm2 and shall conform to Indian Standard IS:1786 or specification in force that is considered by the Engineer to apply.

The use of cold twisted bars is not permitted. Steel for all bars shall be produced by open hearth, basic oxygen or electric arc furnace methods, unless otherwise called for on the Drawings or in special provisions.

Wire Mesh

Wire mesh shall conform to the requirements of Indian Standard IS 1566 [or AASHTO Standard Specification M 55 -Welded Steel Wire Fabric for Concrete Reinforcement or ASTM A185 / A185M – 07].


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Binding Wire

Reinforcement binding wire shall be best black annealed mild steel wire, approximately 1.6 mm in diameter.

Bar Sizes

Metric sizes of steel are shown on the Drawings and shall be used.

Ordering Material

The name of the proposed supplier (or names of proposed suppliers) of the reinforcement shall be submitted as soon as possible to the Engineer for his approval. The Contractor shall also submit all relevant data on the steel required by the Engineer, such as breaking strength, yield strength, characteristics on elongation, chemical composition etc.

Copies of orders placed shall be submitted to the Engineer.

No steel shall be delivered without a manufacturer’s certificate guaranteeing the yield stress, which shall be submitted to the Engineer.

The steel shall be stored on Site and marked in a way that later enables identification of the steel corresponding to each certificate.

Additional Tests

The Contractor shall cut out steel samples as directed by the Engineer and these shall be tested according to the Engineer’s instructions by an approved Testing Institution. Expenses incurred in connection with cutting out, transporting and testing of the samples shall be paid for by the Contractor. In general, two samples shall be tested from each batch of a particular size of reinforcement delivered to the site.

3.8.3 Construction Methods

Protection and Storage

Reinforcement for structures shall be handled and stored in a manner that will prevent bending out of the desired shape and any accumulation of dirt, oil and paint. When placed in the works it shall be free from dirt, oil, grease, paint, mill scale and loose or thick rust.

Cutting and Bending

Bars shall be cut and bent cold to the dimensions indicated and with equipment and methods approved by the Engineer.

Stirrups and tie bars shall be bent around a pin having a diameter not less than four times the minimum thickness of the bar. Bends for other bars, where full tension in the bar may occur, shall be made around a pin having a diameter not less than twenty times the bar diameter. Hooks shall conform to IRC:112 - 2011or as shown in the Drawings.

Placing, Supporting and Fastening

All bar reinforcement shall be placed, supported and secured prior to any concreting operations. The reinforcement shall be checked and approved by the Engineer before pouring of concrete.

Cover blocks required for ensuring that the reinforcement is correctly positioned shall be as small as possible, consistent with their purpose, of a shape and material acceptable to the Engineer, and


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designated so that they will not overturn when the concrete is placed. If made of concrete, the maximum size of aggregate shall be 6 mm and the mix proportion shall be one part of cement to 2 parts of sand by weight. Wire shall be cast in the block for the purpose of tying it to the reinforcement. The wire must not be closer than 30 mm from the concrete surface. The use of small stones or wood blocks shall not be permitted.

The reinforcement shall be held securely in place at the exact position and at the exact spacing as indicated on the Drawings by the use of wire ties at bar intersections, supports and cover blocks. Wire ties shall be securely tied and folded so that they do not project beyond the planes formed by the reinforcing bars. The adequacy of the supports and ties to secure the reinforcement properly shall be subject to the approval of the Engineer.

Splicing

Reinforcement shall be furnished in the lengths indicated on the Drawings. When the Contractor wishes to use more splices than are indicated and/or necessary, the Contractor shall furnish Working Drawings to the Engineer for approval in accordance with the guidelines provided on the Contract Drawings. If such additional splices are approved, the extra weight occasioned by such splices shall not be included in the measurement of reinforcement for payment.

All splices for high yield deformed steel bars and mild steel plain steel bars shall have lap lengths as shown on the Drawings. Lap splices shall generally be located at points of minimum tension in bars. Except where otherwise shown on the Drawings lap splices shall be made with the bars placed in contact and securely wired together.

Welding of reinforcing steel shall be done only if detailed on the Drawings or approved in writing by the Engineer. Before the Engineer may approve of such welding, the Contractor shall submit and test any samples as the Engineer may require and make due allowance for the time elapsing before results are available.

Substitutions

Substitutions of bars shall be permitted only with specific authorization by the Engineer and at the expense of the Contractor. If bars are substituted they shall have a cross sectional area equivalent to the design area, or larger. If substitutions of bars are permitted, the Contractor shall produce working drawings and reinforcing detailing at his own expense and to the approval of the Engineer. Substituted bar must be tested as per requirement of the Engineer.

3.8.4 Measurement

The quantity of reinforcement to be measured under this Section shall be the computed weight in tonnes of material used and accepted as shown on the Drawings provided that the quantity shall not include the reinforcement in any item of work for which the basis of payment includes the reinforcement. In computing the weight to be measured, the theoretical weights of bars of the cross section shown on the Drawings or authorized shall be used. The weight shall be calculated based on a constant mass of 0.00785 kg/mm2 per Meter run.

The computed weight shall not include the extra material incurred when bars larger than those specified are used, or the extra material necessary for splices when bars shorter than those specified are used with the permission of the Engineer, or the weight of any devices used to support or fasten the reinforcement in the correct position including any necessary Chairs for Slab, Pile/Caisson Caps, Footing or any other structural components. The quantity for the chairs/spacers shown in the drawings


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and accounted for in the bar bending schedule are incorporated in the BoQ and shall be paid for separately at the contract unit price

However, payment shall be allowed for lap splices not shown when the bars are longer than 12 meters, only one lap splice per every 12 meters will be paid for and where required as per construction condition and approved by the Engineer.

3.8.5 Payment

This work measured as provided above, shall be paid for at the Contract unit price per metric tonne (MT) of reinforcement of the particular type. The payment shall be full compensation for furnishing, cutting, bending and placing reinforcement of any size and for all labor, binding wire, equipment, spacer/chair required for placing of reinforcement, tools and incidentals necessary to complete the work prescribed in this Section.

3.9 PRESTRESSING WORKS

3.9.1 Description

This work shall consist of furnishing and placing of pre-stressing cable of standard quality as specified in this specification and the BoQ and in conformity with the requirements shown in the Drawings.

3.9.2 Materials

Prestressing Cable/Tendon

The prestressing cable shall be low relaxation 7-wire strands. The tendons shall be standard 12T13 or equivalent with 12 strands per tendon. The tendons shall be grade 1860 MPa as per Euro norm 138-6/79 super with nominal section area of 100 mm2 or Grade 270 K as per ASTM A416/80 with nominal section area of 98.7 mm2. The guaranteed ultimate tensile load shall be 186 KN per strand. The tendons shall be tensioned symmetrically about centreline of the girder. The tendon profile shall be smooth parabolic curve between specified control points as per the profiles shown in the relevant drawings.

The sheathing duct for housing the tendons shall be corrugated HDPE ducts and shall have diameter of 65 mm.

Ordering Material

The name of proposed supplier (or names of proposed suppliers) or the manufacturers of the pre-stressing cable shall be submitted to the Engineer for the approval. The contractor shall submit all the relevant data of the pre-stressing cable required by the Engineer.

3.9.3 Construction Methods

Protection and Storage

The pre-stressing cable shall be stored in a manner that it will not be rusted before placing in the bridge. It shall be kept in such a way that its shape is not deformed due to careless handling during the transportation and after reaching bridge site.


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Placing, Positioning and Pre-stressing

The tendons will be used for prestressing the girder of the bridge. The pre-stressing cable shall be placed and positioned as per the parabolic profile maintained in the design drawings. The pre-stressing work shall be carried out by specialist personnel with extensive knowledge and experience on the works of similar nature. The tendons shall be tensioned symmetrically about the center line of the girder. If the pre-stressing work is to be sub-contracted, the Contractor shall obtain necessary approval from the Engineer before commencing the works.

Grouting

The grouting to fill the gap between pre-stressing cable and sheath shall be done in such a way that no air voids is left. The air voids will cause rust to pre-stressing cable and result in its deterioration before its service life.

Inspection and Quality control

The team of minimum two Engineers from the Client/Engineer shall inspect the pre-stressing cable/tendons, sheathing ducts and other pre-stressing accessories at the manufacturer’s yard before dispatch to the bridge site to check and confirm that the pre-stressing cables and other accessories are manufactured as per the specifications. Depending on the requirement, the inspection team will demand certain test to be carried out on the materials in line with the provisions of the standard code of practice. The Contractor/Supplier shall be obliged to carry out such tests and verifications at no additional cost to the Client. The expenses for the factory visit including travel (to and from air fare) and DSA as per RGoB rule shall be borne by the contractor and therefore has to be accounted for while setting the rates.

3.9.4 Payment

This work measured as provided above, shall be paid for at the Contract unit price per metric Ton (MT) of pre-stressing tendon. The payment shall be full compensation for complete work done including the labor charge, factory inspection by Client/Engineer, supply of pre-stressing accessories and for tools and machineries involved to complete the work prescribed in this Section.

The rate shall also include anchorage elements, standard steel mesh at the anchorage block, HDPE sheathing ducts of number and size mentioned in the relevant drawings. The number of strands required is specified in the tendon table of the drawings. The rate for the tendons will be accounted from one anchorage plate to the other. The net total length of the tendons is approximately 2,023 m excluding the anchorage length. The rates quoted shall include supply, wastage, cutting, anchorage-length, placing and fixation and all works necessary to fulfill the task. The additional length of tendons required for the anchorage and grip etc. shall not be paid separately. The sheathing duct shall be grouted using Ordinary Portland Cement after the tendons are prestressed. The grouting operation shall be carried out as per the provisions of IRC18-2000. The rate shall include all the materials, equipment and accessories, vent pipes and all the efforts required to fulfill the task in full.


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4 SECTION 4–MISCELLANEOUS

4.1 DRAINAGE FOR STRUCTURES

4.1.1 Description

This work consists of furnishing and erection of drain outlets on bridge decks and drainage of other structures including PVC piping, cleaning boxes, catch basins, concrete drains, erosion protection, inserts, fittings and other incidental parts necessary to provide for further supports of drain pipes in accordance with the lines, levels, grades, sizes, dimensions and types shown on the Drawings.

4.1.2 Drainage Spouts

4.1.2.1 Scope

This work shall consist of furnishing and fixing in position of drainage spouts and drainage pipes for bridge decks as per drawing and specification.

4.1.2.2 Fabrication

The drainage assembly shall be fabricated to the dimensions shown on the drawings; all materials shall be corrosion resistant; steel components shall be of mild steel conforming to IS: 226. The drainage assembly shall be seam welded for water tightness and then hot-dip galvanized.

4.1.2.3 Placement

The galvanized assembly shall be given two coats of bituminous painting before placement. The whole assembly shall be placed in true position, lines and levels as shown in the drawing with necessary cut-out in the shuttering for deck slab and held in place firmly. Where the reinforcements of the deck are required to be cut, equivalent reinforcements shall be placed at the corners of the assembly.

4.1.2.4 Finishing

After setting of the deck slab concrete, the shrinkage cracks around the assembly shall be totally sealed with bituminous sealant as per IS:1834 and the excess sealant trimmed to receive the wearing coat. After the wearing coat is completed, similar sealant shall be finished to cover at least 50 mm on the wearing coat surface all round the drainage assembly.

4.1.2.5 Measurements

The measurement for payment for Drainage spouts shall be number/piece.

4.1.2.6 Payment

The contract unit rate for each drainage spout shall include the cost of all labor, materials tools and plant required for completing the work as per these Specifications. It shall also include the cost of providing flow drain pipes with all fixtures up to the point of ground drains wherever shown on the drawings.


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4.2 HDPE DRAINAGE PIPES

4.2.1 Scope

This work shall consist of providing HDPE drainage pipes on the deck slab underneath the foot path slabs.

Material

All HDPE pipes shall comply with Indian Standard IS 13592 or ISO D1785:08 Standard Specification for High Density Polythene pipe (HDPE) Plastic Pipes.

Placement

The pipes shall be placed in true position, lines and levels as shown in the drawing with necessary cut-out in the shuttering for deck slab and held in place firmly. Where the reinforcements of the deck are required to be cut, equivalent reinforcements shall be placed around the pipes. The ends of pipes during construction shall be closed against the intrusion of foreign material.

4.2.2 Measurement

The drainage pipes shall be measured in running metre for the shape and diameter shown in the drawings.

4.2.3 Payment

HDPE drainage pipes as shown in the drawings and defined in the BoQ, will be paid for at the Contract unit price.

The price and payment shall constitute full compensation for furnishing all materials as indicated in the Drawings including delivery, placement, finishing and for all labor, equipment, tools and incidentals necessary to complete the work.

4.3 ELASTOMERIC BRIDGE BEARINGS

4.3.1 Scope

The purpose of bridge bearing is to spread the load over a pre-determined area of beam above and of the pier and abutment below, while permitting an adequate amount of elastic and temperature movements. The degree of sophistication needed in a bearing will depend on the load to be carried and the number of movements (e.g. translations and rotations) to be allowed for; also for the lateral forces to be resisted in a direction at right angles to the primary movements.

Design life of bearing is not generally as long as the bridge. Provision must be made for their replacement as well as their regular inspection. This requires that the bridge can be jacked up and that bearings can be removed without too much difficulty.

4.3.2 Steel reinforced Elastomeric Bearings

An elastomeric bridge bearing is a device constructed partially or wholly from elastomer. The purpose of this is to transmit loads and accommodate movements between a bridge superstructure and its supporting structure. Steel-reinforced elastomeric bearing shall consist of alternate layer of steel reinforcement and elastomer bonded together. In addition to any internal reinforcement, bearings may have external steel load plate bonded to either or both the upper or lower elastomer layers.


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Bearings should be furnished with dimensions, material properties, elastomer grade and type of laminates required by the drawings.

4.3.3 Properties of Elastomer

The raw elastomer shall be either virgin Neoprene (polychloroprene) or virgin natural rubber (polyisoprene). The elastomer compound shall be classified as being of low temperature grade. The elastomer shall have a shear modulus between 0.9 and 1.3MPa. It shall conform to the requirements of IRC:83 (Part II).

4.3.4 Steel Laminates

Steel laminates used for reinforcement shall be made from rolled mild steel conforming to IS 2062 or ASTM A36, A570 or equivalent unless otherwise specified by the Engineer. The laminates shall have a minimum thickness as shown on the drawings. Holes in plates for manufacturing purposes will not be permitted unless they have been accounted for in the design and shown on the drawing.

4.3.5 Bond

The vulcanised bond between elastomer and reinforcement shall have a minimum peel strength of 5.2 kN/m. Steel laminated bearings shall develop a minimum peel strength of 6.9 kN/m.

4.3.6 Manufacture

Bearing with steel laminates shall be cast as a unit in a mould and shall be bounded and vulcanised under heat and pressure. The mould finish shall conform to standard shop practice. The internal steel laminates shall be sand blasted and cleaned of all surface coatings, rust, mill scale, and dirt before bonding, and shall be free from sharp edges and burrs. Bearings that are designed to act as a single unit with a given shape factor must be manufactured as a single unit.

4.3.7 Fabrication Tolerances

Plain pads and laminated bearings shall be built to the specified dimension within the following tolerances:

Design Thickness 32mm (1¼ in.) or less - - 0, + 3mm

Design Thickness over 32mm - - 0, + 6mm

Overall Horizontal Dimension 914mm (36 in.) or less - - 0, + 6mm

Thickness of Individual Layers of ± 20% of design Elastomer (Laminated Bearings only) value but not At any point within the bearings more than ± 3mm

Parallelism with opposite face - 0.005 radian

Top and bottom sides - 0.02 radian

Edge Cover -

Embedded Laminates - - 0, + 3mm

Thickness -


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Top and bottom cover Layer - - 0, the smaller of + 1.5mm and + 20% of the nominal cover layer thickness.

4.3.8 Marking and Certifying

The manufacturer shall certify that each bearing satisfies the requirements of the drawings and these specifications, and shall supply a certified copy of material test results. Each reinforced bearing shall be marked with indelible ink or flexible paint the bearing identification number, elastomer type and grade number. The marking shall be on the face that is visible after erection of the bridge.

4.3.9 Testing

i) General

Materials for elastomeric bearings and the finished bearings themselves shall be subjected to the tests described in the drawings.

ii) Ambient Temperature Tests on the Elastomer

The elastomer used shall atleast satisfy the limits prescribed in the AASHTO for durometer hardness, tensile strength, ultimate elongation, heat resistance, compression set, and ozone resistance. The bond to the reinforcement, if any, shall also satisfy the stipulated requirements. The shear modulus of the material shall be tested at 23°c (73°F) using the apparatus and procedure described in Annexure A of ASTM D4014. It shall be either equal to or greater than the value shown on the drawing.

iii) Visual Inspection of the Finished Bearing

Every finished bearing shall be inspected for compliance with dimensional tolerances and for overall quality of manufacture. In steel reinforced bearings, the edges of the steel shall be protected everywhere from corrosion.

iv) Short Duration Compression Tests on Bearings

The bearing shall be loaded in compression to 1.5 times the maximum design load. The load shall be held constant for 5 minutes, removed, and re-applied for another 5 minutes. The bearing shall be examined visually while under the second loading. If the bulging pattern suggests laminate parallelism or a layer thickness that is outside the specified tolerances, or poor laminate bond the bearing shall be rejected. If there are three or more separate surface cracks that are greater than 0.2mm (0.08 in.) wide and 0.2mm (0.08 in.) deep, the bearing shall be rejected.

v) Long-Duration Compression Tests on Bearings

The bearing shall be loaded in compression to 1.5 times its maximum design load for a minimum period of 15 hours. If, during the test, the load falls below 1.3 times the maximum design load, the test duration shall be increased by the period of time for which the load is below this limit. The bearing shall be examined visually at the end of the test while it is still under load. If the bulging pattern suggests laminate parallelism or a layer thickness that is outside the specified tolerances or poor laminate bond the bearing shall be rejected. If there are three or more separate surface cracks that are greater than 0.2mm (0.08 in.) wide and 0.2mm (0.08 in.) deep, the bearing shall be rejected.

vi) Shear Modulus Tests on Material from Bearings

The shear modulus of the material in the finished bearing shall be evaluated by testing a specimen cut from it using the procedure given in annex A of ASTM D4014. If the test is conducted on finished


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bearings, the material shear modulus shall be computed from the measured shear stiffness of the bearing, taking due account of the influence on shear stiffness of bearing geometry and compressive load.

4.3.10 Installation

Bearings shall be placed on surfaces that are plane to within 1.5mm (1/16 in.) and horizontal to within 0.01 radian. Any lack of parallelism between the top of the bearing and the underside of the girder that exceeds 0.01 radian shall be corrected by grouting or as otherwise directed by the Engineer.

In order to function correctly the elastomeric bearings must be placed with particular care.

As a general rule, the bearings must be placed on a perfectly plane and horizontal surface. A 30 to 40 mm high mortar pad or for larger height the RC pad is cast onto the base concrete, which must be previously carefully roughened. The dimensions of the pad must be by 30 to 50 mm larger than those of the bearing.

When minimum loads are small, it is recommended to glue the bearing to the support with an epoxy resin.

The bottom face of the pre-cast unit, in contact with the bearing, must be perfectly plane and horizontal.

For cast-in-situ structures, the bearing is placed on the support and the structure cast on the bearing. The shuttering surrounding the bearing must be removable at the time of stripping the forms and at the same time it must be strong enough to resist the weight of concrete. If the base shuttering fails, the bearing will be partially embedded in the concrete and the distortions hindered. Future lifting of the structure may become more difficult.

4.3.11 Measurement

Elastomeric bearing is measured by the total number of complete bearing installed at the specified bridge location.

4.3.12 Payment

Elastomeric bearing measured in accordance with Section 4.3.11 shall be paid for at the Contract unit prices for providing bearings in the locations indicated on the Drawings and described in the Bill of Quantities. Payment shall be full compensation for furnishing and installing all materials, including alllabor, tools, equipment and incidentals necessary to complete the work.

4.4 MOVEMENT OR EXPANSION JOINTS

4.4.1 Scope of Work

The scope of work will include:

i) Preparation of detailed engineering and installation drawings, supply and supervision during fixing of strip seal/compression seal expansion joints conforming to specifications. The expected expansion/contraction of the superstructure at the location of expansion joints are shown in relevant approved drawings.

ii) Design manufacture, providing and seating of expansion joints by the specialized agency and approved by the Engineer.


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iii) Necessary technical supervision for installation of each and every expansion joint during different stages of installation including rectification of any deficiency or defect attributable to fixing and installation will be provided by the manufacturer/supplier. The expansion joint shall be provided for the full width of bridge including the railing. Leak tightness of all joints shall be ensured.

4.4.2 Specification for Strip Seal Expansion Joint

Expansion joint type described here–after is the “strip seal type”, but alternate designs can be proposed for the Engineer’s approval.

Components:

Strip seal expansion joint shall comprise the following items:

a) Edge beam:

This shall be either extruded or hot rolled steel section or cold rolled cellular steel section with suitable profile to mechanically lock the swelling element in place throughout the normal movement cycle. Further the configuration shall be such that the section has a minimum thickness of 10 mm all along its cross section (flanges and web) the minimum height of the edge beam section shall be 50 mm and the minimum cross sectional area of the edge beam shall be 1500 sq.mm.

b) Anchorage

Edge beams shall be anchored to the deck/dirt wall/approach slab by reinforcing bars or bolts or anchor plates cast in concrete or a combination of anchor plate and reinforcing bars. Anchor bars studs or bolts shall engage the main structural reinforcement of the deck and in case of anchor plates or loops, this shall be achieved by passing transverse bars through the loops or plates.

The minimum thickness of anchor plate shall be 12 mm. Total cross sectional area of bar on each side of the joint shall not be less than 1600 sq.mm per meter length of the joint and the center to center spacing shall not exceed 250 mm. The ultimate resistance of anchors shall not be less than 600 kN/m in any direction.

Material

a) The steel for edge beams shall conform to any of the steel grade corresponding to RST37-2 or 37-3 (DIN), ASTM A 36 or A 588, CAN/CSA standard G40.21 Grade 300W or equivalent. b) Anchorage steel shall conform to IS: 2062 or equivalent.

c) All steel sections shall be protected against corrosion by hot dip galvanizing or any other approved anticorrosive coating with a minimum thickness of 100 micron.

d) Chloroprene of strip seal element shall conform to clause 9151.1 of IRC:83 (Part-ll) The properties of chloroprene shall be as specified in Table 4.4-1

Fabrication (Pre-installation)

a) The strip seal joint system and all its component parts including anchorages shall be supplied by the manufacturer/ system supplier.

b) The width of the gap to cater for movement due to thermal effect, pre stress, shrinkage and creep, superstructure deformations (if any) and sub-structure deformations (if any) shall be determined and


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intimated to the manufacturer depending upon the temperature at which the joint is to be installed, the gap dimension shall be preset.

Table 4.4-1Strip Seal Element Specifications

Sl. No Property Specified Value 1 Hardness 63+/- shore A 2 DIN 53505 55+/- Shore A 3 ASTM D (Modified) 4 Tensile strength Min. 11 MPa 5 DIN 53504 Min. 13.8 MPa 6 ASTM D412 7 Elongation at fracture Min. 350 per cent 8 DIN 53504 Min. 250 per cent 9 ASTM D412

10 Tear Propagation strength Min. 10 N/mm 11 Longitudinal Min. 10N/mm 12 Transverse Min. 25 per cent 13 Shock elasticity Min 220 Cu. mm 14 Abrasion 15 Residual compressive strain (22/70 oC /30 per cent)

Aging in hot air (14 days/70 oC) Max. 28 per cent

16 Change in hardness Max. +7 Shore A 17 Change in tensile strength Max. -20 per cent 18 Change in elongation at fracture -20 per cent 19 Aging in ozone (24h/50pphm/25 deg per cent

elongation) No cracks

20 Swelling behaviour in oil (168h/28 oC) 21 ASTM Oil No. 1 Max. +5 per cent 22 Volume Change Max. -20 Shore A 23 Change in hardness Max. -35 deg C 24 ASTM Oil No. 3 Max. +25 per cent 25 Volume change Max. -25 Shore A 26 Change in hardness Max. -35 deg C 27 Cold Hardening Point

c) Each strip seal expansion joint system shall be fabricated as a single entity unless stage construction or excessive length prohibits monolithic fabrication. It shall fit the full width of the structure as indicated on the approved drawing. The system shall be pre-set by the manufacturer prior to transportation. Presetting shall be done in accordance with the joint opening indicated on the drawing.

d) The finally assembled joint shall them be clamped and transported to the work site.

Handling and Storage

a. For transportation and storage, auxiliary brackets shall be provided to hold the joint assembly together.


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b. The manufacture/ supplier shall supply to the Contractor all the materials of strip seal joints including sealants and all other accessories for the effective installation of the jointing.

c. Expansion joint material shall be handled with care. It shall be stored under cover on suitable lumber padding.

Supply/ Installation

Components of expansion joint such as edge beam and strip seal shall be arranged by the contractor by procuring the same from reputed approved manufacturer to ensure quality and performance. Contractor shall furnish a warranty of trouble free performance for at least ten years and free rectification of defects / replacement, if any, during this period.

The joints shall be installed in compliance to the manufacturer’s instructions for installation.

Taking the width of gap for movement of the joint into account the dimensions of the recess in the decking shall be established in accordance with the drawings or design data of the manufacturer. The surfaces of the recess shall be thoroughly cleaned and all dirt and debris removed. The exposed reinforcement shall be suitably adjusted to permit unobstructed lowering of the joint into the recess.

The recess shall be shuttered in such a way that dimensions in the joint drawing are maintained. The formwork shall be rigid and firm.

Immediately prior to placing the joint, the presetting shall be inspected. Should the actual temperature of the structure be different from the temperature provided for presetting, correction of the presetting shall be done. After adjustment the brackets shall be tightened again.

The joint shall be lowered in a pre-determined position. Following placement of the joint in the prepared recess, the joint shall be leveled and finally aligned and the anchorage steel on one side of the joint welded to the exposed reinforcement bars of the structure. Upon completion, the same procedure shall be followed for the other side of the joint. With the expansion joint finally held at both sides, the auxiliary brackets shall be released allowing the joint to take up the movement of the structure.

High quality concrete shall then be filled into the recess. The packing concrete must feature low shrinkage and have the same strength as that of the superstructure but in any case not less than M30 grade good compaction and careful curing of concrete is particularly important.

After the concrete has cured, the movable installation brackets and shuttering still in place shall be removed.

The neoprene seal shall be field installed in continuous length spanning the entire roadway width. To ensure proper fit of seal and enhance the ease of installation dirt, spatter or standing water shall be removed from the steel cavity using a brush, scrapper or compressed air. The seal shall be installed without any damage to the seal by suitable hand method or machine tools.

The deck surfacing shall be finished flush with the top of the steel sections, the horizontal leg of the edge beam shall be cleaned beforehand. It is particularly important to ensure thorough and careful compaction of the surfacing in order to prevent any premature depression forming in it.

Acceptance criteria

a. All steel elements shall be finished with corrosion protection system


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b. For neoprene seal, the acceptance test shall conform to the requirements stipulated in Table 4.4-1.The manufacturer/ supplier shall produce a test certificate accordingly, conducted in a recognized laboratory, in India or abroad.

c. The manufacturer shall produce test certificates indicating that anchorage system had been tested in recognized laboratory to determine optimum configuration of anchorage assembly under dynamic loading.

d. Prior to acceptance 25 percent of the completed and installed joints, subject to a minimum of one joint, shall be subjected to water tightness test. Water shall be continuously pounded along the entire length for a minimum period of 4 hours for a depth of 25mm above the highest point of deck. The width of ponding shall be at least 50mm beyond the anchorage block of the joint on either side. The depth of water shall not fall below 25mm anytime during the test. A close inspection of the underside of the joint shall not reveal any leakage.

e. As strip seal type of joint is specialized in nature, generally of the proprietary type, the manufacturer shall be required to produce evidence of satisfactory performance of this type of joint.

Test and standards for acceptance:

The materials shall be tested in accordance with these specifications and shall meet the prescribed criteria. The manufacturer/supplier shall furnish the requisite certificates from the recognized laboratory in India or abroad.

4.4.2 Measurement

Expansion joints shall be measured by the linear Meter of complete joint installed, measurement being along a straight line from base to top of a wall or one side of a slab to the other, etc. The measured length may therefore include a sealant length of over twice this value if several faces of the concrete are sealed.

4.4.3 Payment

Expansion joints measured in accordance with Section 4.4.2 shall be paid for at the Contract unit prices for providing joints in the locations indicated on the Drawings and described in the Bill of Quantities. Payment shall be full compensation for furnishing and installing all materials, including alllabor, tools, equipment and incidentals necessary to complete the work.

4.5 BRIDGE RAILING

4.5.1 Scope

This work shall consist of providing railings on both sides of the bridge as per the details shown in the design drawings.

4.5.2 Material

The components of the railing shall be in reinforced concrete and steel members as shown in the drawings. The grade of concrete and the reinforcement bar shall be as stipulated in the design drawings.


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4.5.3 Placement

The railings shall be placed in true position, lines and levels as shown in the drawing. The components of the railing – posts, rail and tsegay (Bhutanese architectural design) shall be smooth form finished and no cement mortar plastering shall be permitted.

4.5.4 Measurement

The railings shall be measured in per running metre for the design and component sizes as shown in the drawings to the nearest 10mm.

4.5.5 Payment

The railing as shown in the drawings and defined in the BoQ, will be paid for at the Contract unit price. The lumpsum running metre rate shall include costs for providing and laying reinforcement bar, providing and removal of the shuttering, providing and laying concrete, curing or concrete and all other works required to complete the task in full.

The price and payment shall constitute full compensation for furnishing all materials as shown in the Drawings including delivery, placement, centering & shuttering, providing supports, finishing and for all labor, equipment, tools and incidentals necessary to complete the work.


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5 SECTION 5 -STONE MASONRY WORK

5.1 Scope

This Section covers furnishing of materials and construction of different types of stone masonry works in accordance with the Drawing and this Specification or as directed by the Engineer. These works will be required for retaining structures, drains and channel lining, slope and drainage protection works or other works as directed by the Engineer.

Activities involved will include supply of stones, dressed bond stone, cement, sand, water, equipment, tools & plants, preparation of mortar, placing and joining stones dry/with mortar, curing, collection and testing of specimens, etc.

5.2 Materials

All requirements in respect of stones and cement sand mortar described herein shall be applicable in all Clauses of this Section, if otherwise not specified.

(1) Stone The stones to be used shall be durable and angular in shape. If boulders are used they shall be broken into angular pieces. The stones shall be sound, hard, and free from iron bands, spots, sand holes, flaws, shakes, cracks or other defects. The stone shall not absorb water more than 5 per cent. Stones for coursed or uncoursed stone rubble masonry shall have broken face on three sides. Stones for dressed rubble masonry shall have dressed face on all sides. Except otherwise described in the contract, the length of any stone shall not exceed three times its height. The breadth of the stone on the bed shall not be less than 150 mm nor greater than 3/4th thickness of the wall. At least 80% of the stones used in masonry, except those used for chinking as chips or spalls of stones shall have individual volumes of more than 0.01 m3. The chips or spalls used including voids in the dry stone masonry shall not be more than 20% of the stone masonry by volume. In case of mortared masonry the total volume of mortar and spalls taken together shall not be more than 30% of the mortared masonry. Representative samples of the stones intended for use in the works shall be submitted to the Engineer for prior approval. Further representative samples shall be submitted for approval whenever there is a change in the type or strength of the rock that the Contractor intends to use in masonry work.

(2) Mortar Mortar shall comply with IS 2250–1981, Code of Practice for preparation and use of masonry mortar. The mortar used in work shall have the strength not less than 5 N/mm2 or 7.5 N/mm2 at 28 days as specified. For example class MM5 means cement sand mortar in the ratio to attain compressive strength not less than 5 N/mm2 at 28 days. The grade of cement sand mortar shall be as specified in the Bill of Quantities.

Sand shall comply with IS 2116. Cement shall be ordinary Portland cement as per IS 8112 or IS 12269. Water shall be clean and free from detrimental concentration of acids, alkalis, salts, and other organic or chemical substances. If instructed by the Engineer the Contractor shall prove the suitability of the water by tests carried out by an approved laboratory. Such tests shall comply with the requirements of IS: 3029-1964.

The mixing shall be done in a mechanical mixer unless hand-mixing is permitted by the Engineer. If manual mixing is allowed, the operation shall be carried out on a clear watertight platform. The cement and sand shall be first mixed dry in the required proportion to obtain uniform colour. Then required quantity of water shall be added and the mortar shall be mixed to produce workable consistency. The mortar shall be mixed for at least three minutes after addition of water in the case of mechanical mixing. In the case of manual mixing, the mortar shall be hoed back and forth for about 10 minutes after addition of water in order to obtain uniform consistency. Only that quantity of mortar shall be mixed at a time which can be used completely before it becomes unworkable. Any mortar that has become unworkable due to loss of water before elapsing the initial


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setting time of cement shall be rewet to make it workable and shall be used in the works. On no account mortar shall be used after elapsing the initial setting time of cement.

5.3 Construction

The method of construction described herein shall hold good in all Clauses of this Section, wherever applicable.

(1) General Construction shall be carried out in accordance with IS : 1597-1992, Code of Practice for construction of stone masonry, Part 1 - Rubble stone masonry or Part 2 - Ashlar Masonry as appropriate. All stratified stone possessing bedding planes shall be laid with its natural bed as nearly as possible at right angles to the direction of load. In the case of arch rings, the natural bed shall be radial. Facework groins shall be built to a height not exceeding one metre in advance of the main body of the work and adjacent walling stepped down on either side. Masonry face work between the groins shall then be built to a height not exceeding 500 mm above the backing which shall then be brought up level with the completed facework. At no time shall the backing be built up higher than the facework. Except for dry rubble walling, all joints (gaps) shall be sufficiently thick to prevent stone to stone contact and the gaps shall be completely filled with mortar. Stones shall be clean and sufficiently wetted before laying to prevent absorption of water from mortar. Placing loose mortar on the course and pouring water upon it to fill the gaps in stones shall not be allowed. Mortar shall be fluid, mixed thoroughly and then poured in the joints. No dry or hollow space shall be left anywhere in the masonry and each stone shall have all its faces completely covered with mortar of the thickness as specified for joints. The bed which is to receive the stone shall be cleaned, wetted and covered with a layer of fresh mortar. All stones shall be laid full in mortar both in bed and vertical joints and settled carefully in place with a wooden mallet immediately after placement and solidly embedded in mortar before it has set. Clean and wet chips and spalls shall be wedged into the mortar joints and bed whenever necessary to avoid thick joints or bed of mortar. When the foundation masonry is laid directly on rock, the bedding face of the stones of the first course shall be dressed to fit into rock snugly when pressed down in the mortar bedding over the rock. For all masonry works, a levelling course of M15/20 concrete 100mm thickness shall be laid to ensure a level and stable foundation. In case, any stone already set in mortar is disturbed or the joints broken, it shall be taken out without disturbing the adjoining stones and joints. Dry mortar and stones shall be thoroughly cleaned from the joints and the stones shall be reset in fresh mortar. Sliding one stone on top of another which is freshly laid shall not be allowed. Shaping and dressing of stone shall be done before it is laid in the work. Dressing and hammering of the laid stones which will loosen the masonry shall not be allowed. Building up face wall tied with occasional through stones and filling up the middle with stones spalls and chips or dry packing shall not be allowed. Vertical joints shall be staggered. Distance between the nearer vertical joints of upper layer and lower layer in coursed rubble masonry shall not be less than half the height of the course. Masonry in a structure between two expansion joints shall be carried up nearly at one uniform level throughout but when breaks are unavoidable the masonry shall be raked in sufficiently long steps to facilitate jointing of old and new work. The stepping of raking shall not be more than 45 degrees with the horizontal. Masonry shall not be laid when the air temperature in the shade is less than 3°C. Newly laid masonry shall be protected from the harmful effects of weather.


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The holes left in the masonry work for supporting scaffolding shall be filled and finished with M15 grade concrete. The masonry work in cement mortar shall be kept constantly moist for a minimum period of 7 days, unless otherwise specified. (2) Concrete Capping Where masonry structures are constructed to receive a concrete capping the joints to the upper surface of the masonry shall be raked out to a depth of 10 mm prior to placing of the concrete to the capping. The concrete for capping shall be as per the Drawing or as directed by Engineer and shall conform to Section 3. (3) Pointing Where external faces of the mortared masonry work will be backfilled or otherwise permanently covered up, the mortared joint shall be finished flush to the faces of the adjacent stonework. Where mortared masonry faces will remain exposed, the mortar joints shall be pointed to a consistent style only if shown on the Drawings and/or as directed by the Engineer. Pointing shall be carried out using mortar MM7.5 cement mortar as shown on the Drawing or as directed by the Engineer. The mortar shall be filled and pressed into the raked out joints before giving the required finish. The pointing, if not otherwise mentioned, shall be ruled type for which it shall, while masonry work is still green, be ruled along the centre with half round tools of such width as may be specified by the Engineer. The excess mortar shall then, be taken off from the edges of the lines and shall not be unnecessarily plastered over the exposed stone works. The thickness of the joints shall not be less than 3mm for Ashlar masonry. However, the maximum thickness of joints in different works shall be as follows:

• Random Rubble : 20mm • Coursed Rubble : 15mm • Ashlar Masonry : 5mm

(4) Weep holes

Weep holes shall be provided in solid plain concrete/reinforced concrete, brick/stone masonry, abutment, wing wall or other structures as shown on the Drawing or as directed by the Engineer. Weep holes shall be provided with 100mm diameter polythene pipe for structures in plain/reinforced concrete or brick masonry. In case of stone masonry, weep holes shall be 100 mm wide, 100 mm high or circular with 100 mm diameter. Weep holes shall extend through the full width of concrete/masonry with a slope of 1 vertical 20 horizontal towards the draining face. The spacing of weep holes shall generally be 1 m in either direction or as shown on the drawing with the lowest at about 150 mm above the low water level or ground level whichever is higher or as directed by the Engineer. Surfaces of the weep holes shall be smooth and it shall be ensured that the water is properly drained from the backfill.

5.4 Random Rubble – Coursed or Uncoursed

All stones shall be carefully set with bond stones running right through the thickness of walls up to 600 mm thickness and in case of walls above 600 mm thickness a set of two or more bond stones overlapping each other by minimum 150 mm shall be provided in a line from face to back. At least one bond stone or a set of bond stones shall be provided for every 0.5 m2 of the wall surface. If the bond stone of sufficient length is not available then plain cement concrete (M15 grade concrete) block of cross-section not less than 200x150 mm shall be provided.

In case of highly absorbent types of stones (porous lime stone and sand stones etc) the bond stone shall extend about two third into the wall. The bond stones in such cases may give rise to damp


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penetrations therefore, for all thickness of such walls, a set of two or more bond stones overlapping-each other by at least 150 mm shall be provided.

For random rubble masonry, the face stones shall be hammer dressed on all beds and joints and the quoins shall be of selected stones neatly dressed with the hammer chisel to form the required angle, and laid header and stretcher alternately.

In case of coursed rubble masonry, the face stones shall be hammer dressed on all beds and joints so as to give them approximately rectangular block shape. The bed joint shall be dressed for at least 80 mm back from the face and side joints for at least 40 mm such that no portion of the dressed surface is more than 10 mm from a straight edge placed on it. The remaining portion of the stone shall not project beyond the surface of bed and side joints. The bushing on the face shall not project more than 40 mm on exposed face and 10 mm on a face to be plastered. The face stones shall be laid alternate headers and stretchers without pinning on the face. Bond stones shall be provided as specified above except that the spacing of a bond stone or set of bond stones shall be about 1.5 m or as directed by the Engineer. The quoins shall be of same height as the course. These shall be minimum 380 mm long and laid alternate header and stretcher.

2.5 Dry Random Rubble

Dry random rubble masonry shall be constructed generally to the requirements of coursed random rubble masonry as specified in Sub-Section5.4 but with the omission of mortar. All stones shall be carefully shaped to obtain as close a fit as possible at all beds and joints, any interstices between the stones being filled with selected stone spalls. No round stones shall be used in dry stone masonry work. The stones in courses shall be laid perpendicular to the batter face. Bond stones shall be provided at the rate of at least 10 percent of volume of dry stone masonry structure. Bond stones shall measure not less than 150 mm x 150 mm and not less than 450 mm in length or full thickness of wall, whichever is less. The exposed tops or capping of dry rubble structures shall be formed as shown on the Drawing or as directed by the Engineer.

2.6 Composite Random Rubble

Materials for composite random rubble shall comply with Sub-Section 5.2 and construction with Sub-Section 5.3. Mortar masonry shall be coursed and comply with Clause 5.4 and the dry stone insets with Sub-Section 5.5. The dry stone insets shall be constructed when the level of the surrounding mortared masonry surround has reached the top of the dry stone inset.

2.7 Stone Pitching

(1) General

Stone pitching work shall be required for lining of drains and channels.

(2) Material

The stones to be used shall be durable and angular in shape. If boulders are used they shall be broken into angular pieces. The stones shall be sound, hard, and free from iron bands, spots, sand holes, flaws, shakes, cracks or other defects. The stone shall not absorb water more than 5 per cent. Stones for pitching shall not be less than 150 mm in minimum dimension. Rounded stones shall not be used in stone pitching. The mortar shall comply with Sub-Section 5.2(2).

(3) Mock-Up

Prior to commencement of any stone pitching work the Contractor shall construct a stone pitching panel of approximately 2000 mm x 1000 mm as a trial. The trial if accepted by the Engineer shall be the sample for actual work.

4) Construction


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Stone pitching shall be done on surface prepared to specified requirements. Stones shall be laid in mortar with their longitudinal axis across to the direction of flow. Thickness of mortar in bed shall be 25 to 35 mm. They shall be well set into the surface. Thickness of pitching will be as shown on Drawings or as directed by the Engineer. Spaces between stones shall be filled with spalls. Finished surface shall present an even, tight and neat appearance with no stones varying by more than 20 mm from specified grades and lines. Joints between the stones shall be completely filled with MM 7.5 mortar. Finished surface shall present an even, tight and neat appearance with no stones varying by more than 20 mm from specified grades and lines.

2.8 Stone Soling

Stone soling are required in the construction of foundation beds for various structures as directed by the Engineer. Stones shall comply with Sub-Section 5.2 of this specification. Stone soling shall be done on foundation surface prepared as specified. They shall be well rammed into the surface. Spaces between stones shall be filled with spalls or smaller stones securely rammed into voids. The completed work shall present an even, neat and tight surface.

2.9 Test and Standard for Acceptance

Before laying any mortar, the Contractor shall make three sets of mortar test cubes from each source of sand to demonstrate the compliance of the mix to the specified strength. Each set shall comprise two cubes, one to be tested at 7 days and the other to be tested at 28 days. During construction, the Contractor shall make and test mortar cubes at the rate of three cubes for every 10 m3 of masonry to assess the strength subject to a minimum of 3 cubes samples for a days work. Testing of cubes shall be in accordance with IS 2250. The stones shall be tested for the water absorption as per IS1124 and it shall not be more than 5 percent. Sand shall be tested as directed by the Engineer. At least 3 set of tests for stone and sand shall be conducted for every source.

2.10 Measurement

Stone work shall be measured in cubic metres. No separate measurement shall be carried out for pointing, if pointing was carried out. Weep holes shall not be measured separately. No deduction in the volume of structures shall be made for weep holes.

Repairs/rehabilitation of existing structures shall be measured as per their respective unit of measurement. Deductions shall be made for not meeting the thickness of cement grouting at the discretion of Engineer.

2.11 Payment

The stone masonry shall be paid at the respective contract unit prices which shall be the full and the final compensation to the Contractor to complete the work in accordance with these Specifications. The contract unit rate for respective items shall be deemed to have included costs for labor, materials, tools & plants etc and any incidental costs including the costs for providing pointing and weep holes(if required by the drawings).


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6 SECTION 6 -GABION WORK

6.1 Scope

This Section covers the furnishing of materials and construction of gabion works that may be required to act as buttresses, retaining walls, catch walls, stream or river training structures, check dams within gullies, or where placed as mattresses, to prevent stream or gully erosion.

6.2 Materials

(1) Stones

Stones used for filling the gabion boxes or mattresses shall be clean, hard, sound, un-weathered and angular rock fragments or boulders. The specific gravity of the stone shall be not less than 2.50 and the stones shall not absorb water more than 5 percent when tested as per IS:1124-1974 (re-affirmed 2003). The length of any stone shall not exceed three times its thickness. The smallest dimension of any stone shall be at least twice that of the longer dimension of the mesh of the crate. However smaller size of stones as spalls shall be allowed for filling voids and its volume including voids shall not be more than 20 percent of the total volume of the stones.

Before filling any gabion boxes and mattresses the Contractor shall submit representative samples of the rock he proposes to use in the gabions for approval by the Engineer. Further representative samples shall be submitted for approval each time when there is a change in the type and strength of the rock.

(2) Gabions

Gabions shall consist of steel wire mesh crates. The steel wire shall be mild steel wire complying with IS 280. All wires used in the manufacturing of crates and diaphragms, binding and connecting lids and boxes shall be galvanised with a heavy coating of zinc by an electrolytic or hot dip galvanising process. The weight of deposition of zinc shall be in accordance with IS 6745-1972 (re-affirmed 1994). Zinc coating shall be uniform as per IS 2633-1986 (re-affirmed 2006) and be able to withstand minimum number of dips and adhesion test specified in IS 4826-1979 (re-affirmed 2001). Tolerance on diameter of wire shall be + 2.5 percent. The tensile strength of gabion wire shall be between 300 and 550 N/mm2.

All gabions shall be machine made. The wire shall be woven into a hexagonal mesh with a minimum of 3 twists. All edges of the crates shall be finished with a selvedge wire at least 3 gauges heavier than the mesh wire. Gabions shall be manufactured in the standard sizes shown in Table 6.1 with mesh and wire sizes as shown in Table 6.2.

Diaphragms shall be manufactured of the same materials as the parent gabion box and shall have selvedge wire throughout their perimeter. The number and size of diaphragms to be provided with each crate shall be as in Table 6.1. The diameter of gabion wires shall be as per IS 16014-2012. All crates shall be supplied with binding and connecting wire of the gauges shown in Table 6.2 of sufficient quantity to bind all diaphragms and closing edges.

Table 5.1: Standard Size of Wire Mesh Gabions

Dimensions in metres

(Prior to fill)

Number of diaphragms

Dimensions of diaphragms in metres

Volume of crate in cubic metres

1 x 1 x 1 - - 1

1.5 x 1 x 1 1 1 x 1 1.5

2 x 1 x 1 1 1 x 1 2

3 x 1 x 1 2 1 x 1 3


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1 x 1 x 0.5 - - 0.5

2 x 1 x 0.5 1 1 x 0.5 1

3 x 1 x 0.5 2 1 x 0.5 1.5

1 x 1 x 0.3 - - 0.3

2 x 1 x 0.3 1 1 x 0.3 0.6

3 x 1 x 0.3 2 1 x 0.3 0.9

Table 6.2: Standard Sizes of Mesh and Wire in Gabions

Mesh opening mm

Mesh type Thickness of mesh wire

Thickness of binding and lacing wire

Thickness of selvedge wire

(D x H) mm mm mm

114x128 100x120 2.7 – 3.0 2.2 – 2.4 3.4 - 3.9

The mesh opening shall be as instructed by the Engineer.

6.3 Construction of Gabions

(1) General Requirements

Before filling any gabion boxes and mattresses, the Contractor shall submit samples of gabion boxes and/or gabion mattresses assembled, erected and filled with stones for approval which, when approved, shall be retained for reference and comparison with the gabions built as part of the permanent works. The size, type and location of the samples shall be as directed by the Engineer.

Gabion boxes and gabion mattresses shall be assembled, erected and filled with stones in the dry on prepared surfaces except as may be otherwise approved. Approval for assembling and erecting gabions in water shall be given only, if in the Engineer's opinion such a method will produce work in accordance with the Specification.

(2) Preparation of Foundation and Surface for Bedding

The bed on which the gabion boxes or mattresses are to be laid shall be even and conform to the levels shown on the Drawing. If necessary, cavities between rock protrusions shall be filled with material similar to that specified for gabion filling.

(3) Arrangement of Joints

(a) Walls

In walls, gabion boxes shall be placed such that vertical joints are not continuous, but staggered. Aprons shall be formed of headers. If more than one unit is required to obtain the necessary width, units of unequal length shall be used and the joints between them should be staggered.

(b) Channel linings

In channel linings, gabion box and mattress units shall be laid so that the movement of stone inside the mesh due to gravity or flow of water is avoided. Hence, on side slopes, units shall be placed with


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their internal diaphragms at right angles to the direction of the slope and, on inverts, as far as possible, at right angles to the direction of flow.

(c) Assembly

Gabion boxes and gabion mattresses shall be assembled on a hard flat surface. After fabrication, unpacking or unfolding, they shall be stretched out and any kinks shall be removed. Creases shall be in the correct position for forming the boxes or mattress compartments. The side and end panels shall be folded into an upright position to form rectangular boxes or compartments. The top corners shall be joined together with the thick selvedge wires sticking out of the corners of each panel. The tops of all sides and partitions shall be leveled except as may be appropriate to special units. The sides and end panels shall be tied together using binding wire of the thickness given in Table 15.2, starting at the top of the panel by looping the wire through the corner and twisting the wire together. Binding shall continue by looping the wire through each mesh and around both selvedges with three rounds which shall be joined tightly together by twisting and the end shall be poked inside the unit. The diaphragms shall be secured in their correct positions by binding in the same way. The bindings wire shall be fixed using 250mm long nose fencing pliers or equivalent approved tools.

The gabion boxes and gabion mattresses shall be laid in such a manner that the hinges of the lid will be on the lower side on slopes and on the outer side in walls.

Where mattresses are laid horizontally hinges shall not be placed on the downstream side as much as practicable.

(d) Filling

The crates shall be placed in their final position before filling commences. They shall be stretched to their full dimension and securely pegged to the ground or wired to adjacent gabions before filling. The vertical corners shall be kept square and to full dimension by inserting a steel bar of at least 20 mm diameter at each vertical corner, maintaining it in the correct final position throughout the filling process, and removing it when the crate is full. Before filling commences, the selvedges of the crate shall be bound to the selvedges of adjacent crates with binding wire. Where crates are being assembled in position in a wall the binding of the edges of each crate in the assembly process and the binding together of adjacent crates shall be carried out in the same operation.

Before filling with stone, gabions shall be anchored at one end or side and stretched from the opposite end or side by inserting temporary bars and levering them forward. The top and bottom shall be kept stretched by tensioning with tie wires attached to an anchorage or equivalent approved method until the gabion has been filled. The gabions shall be inspected at this stage but before filling with stone to ensure that the tie/wiring has been properly carried out and the gabion boxes or gabion mattresses are not pulling apart. Gabion boxes or gabion mattresses may be tensioned either singly or in the case of a long straight structure by straining a number of units together using an approved tensioning system.

The filling shall be carried out by placing individual stones into the gabion by hand in courses in such a manner that the stones are bedded on each other and bonded as in dry random rubble masonry as per Sub-Section 5.5. No loose stones shall be tipped into the crate and the practice of coursing and bonding the outer layer and filling the interior with unlaid stones shall not be permitted.

All 1m deep gabions shall be filled in three equal layers and 0.5m deep gabions in two equal layers. Horizontal bracing wires made with the same bindings wire as used for tying shall be fixed directly above each layer of the stone in the compartments, the wires being looped round two adjoining meshes in each side of the compartment and joined together to form a double tie which shall be tensioned by wind lassing together to keep the face of the gabions even and free from bulges. Bracing wires shall be spaced horizontally along and across the gabions at distances not greater than 0.33m. Where the upper faces of gabion boxes are not covered with further gabions vertical bracing wires shall be fitted between the top and bottom mesh using two tie wires per square metre of surface.


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The ties shall be fixed to the bottom of the units prior to filling and tied down to the lid on completion. Where a double layer of gabion boxes is used to form an apron both upper and lower layers shall have vertical tie wires.

(e) Securing Lids

The gabion boxes and mattress compartments shall be over filled by 50mm above their tops to allow for subsequent settlement. The lids shall then be tied down with binding wire to the tops of all partition panels. The lids shall be stretched to fit the sides exactly by means of a suitable tool but due care shall be taken to ensure that the gabions are not so full that the lids are overstretched. The corners shall be temporarily secured first.

(f) Tolerance

On completion, the crates shall be completely and tightly filled, square, true to dimensions and the line and level shown on the Drawing. However the tolerance limit permitted in the length, height and width of the gabion boxes and mattresses as manufactured shall be ± 3 percent from the ordered size prior to filling. The tolerances on the wire mesh opening shall be ± 10% on the nominal dimension 'D' values as follows:

Mesh type Nominal dimension 'D' values

80x100 80

100x120 100

However, the number of opening per gabion box/mattress shall not be less than the nominal length divided by 'D' on horizontal direction and nominal height divided by 'H' in vertical direction where D and H are as per Table 5.2.

6.4 Test and Standard for Acceptance

(1) The gabion wire shall be tested for mass, uniformity and adhesion of zinc coating and tensile strength of the wire itself. Failure of test results to comply with the specifications shall lead to the rejection of gabion wires. The test on the samples taken as per Table 6.3 from each lot of the G.I. wire received at the site of the work shall be carried out in accordance with IS 280-197 and IS 4826-1979.

Table 6.3: Scale of Sampling and Permissible Number of Defective coil

No. of coils in a lot No. of coils randomly selected for sampling*

Permissible No. of defective coil

Up to 25 2 0

26-50 3 0

51-150 5 0

151-300 8 1

300 and above 13 1

* One sample per coil shall be tested in all respect.

(2) The stones shall be tested for water absorption. At least 3 set of tests shall be made for every source of material. The test results shall meet the specified criteria.


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6.5 Measurement

Measurement shall be in cubic meters of gabion crates filled with stones and complete in place and the quantity shall be calculated from the dimension of the gabions indicated in the Drawing or ordered by the Engineer.

6.6 Payment

Payment shall be made as per respective contract unit rate which shall be the full and the final payment to the Contractor to complete the work in accordance with these Specifications.

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