importance of practical training 9

7/31/2019 Importance of Practical Training 9

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Slump testThe concrete slump test is used for the measurement of a property of fresh concrete.

The test is an emprical test that measures the workability of fresh concrete. Morespecifically, it measures consistency between batches. The test is popular due to thesimplicity of apparatus used and simple procedure. The slump test is used to ensureuniformity for different batches of similar concrete under field conditions and to ascertainthe effects of plasticizers on their introduction.

The slump test result is a measure of the behaviour of a compacted inverted cone ofconcrete under the action of gravity. It measures the consistency or the wetness ofconcrete.

The slump is termed as true slump, shear slump or collapse slump. If a shear orcollapse slump is achieved, a fresh sample should be taken and the test repeated. Acollapse slump is an indication of too wet a mix. Only a true slump is of any use in thetest. A collapse slump will generally mean that the mix is too wet or that it is a highworkability mix, for which slump test is not appropriate. Very dry mixes; having slump 0 -25 mm are used in road making, low workability mixes; having slump 10 - 40 mmare used for foundations with light reinforcement, medium workability mixes; 50 - 90 fornormal reinforced concrete placed with vibration, high workability concrete; > 100 mm.

CuringCuring is the process of controlling the rate and extent of moisture loss fromconcrete during cement hydration.

It may be either after it has been placed in position (or during the manufacture ofconcrete products),thereby providing time for the hydration of cement to occur.Since the hydration of cement does take time in days, and even in weeks ratherthan in hours, curing must be done for a reasonable period of time if concrete isto achieve its potential strength and durability. Curing may also encompass thecontrol of temperature since this affects the rate at which cement hydrates.


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Purpose

Curing serves two main purposes.

It retains moisture in the slab so that concrete continues to gain strength

It delays drying shrinkage until the concrete is strong enough to resist

shrinkage cracking.

Properly curing concrete improves strength,durability,water tightness, and waterresistance.


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PROCESSES OF CURING Water cure:

The concrete is flooded,ponded or mist sprayed. This is the most effectivecuring method for preventing mix water evaporation.

Water retaining methods:

Use coverings such as sand,canvas,burlap,or straw that are keptcontinuously wet. The material used must be kept damped during thecuring period.

Water proof paper or plastic film seal:

These are applied as soon as the concrete is hard enough to resist thesurface damage. Plastic films may cause discolouration of concrete. So donot apply to concrete where appearance is important.

Chemical membranes: The concrete application should be made as soon as the concrete isfinished.

Following methods are to be adopted for CURING different parts of buildings:

Walls-Water should be sprinkled from the top such that it covers the whole areaof the wall and it should remain wet.

Slab-Ponding should be done on the slab by constructing bunds of mortar.

Beams and columns-The beams and columns can be maintained wet by tyinggunny bags /Hessian clothes around the periphery and by maintaining it wetalways.


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Compaction

Compacting reinforced concrete work is very important and is done using ironrods. In case the thickness of concrete is more than 15cm,the most satisfactorymethod for compacting concrete properly is to consolidate each layer separatelyso that its top surface become level and fairly smooth before the next layer isplaced. While tamping is carried out, care should be taken that rod shouldpenetrate the full layer of last layer placed and to some extent into lying to ensureproper bond between them. Secondly the reinforcement and formwork should notbe disturbed from their positions.

Mechanical compaction is done by use of vibrators.Compaction of concrete

done by vibration is considered essential for all important works especially insituations where reinforcements are congested or the member is required tohave exposed concrete finish. When vibrators are used, leaner but stiff concretemix should be used to obtain greater durability and highest strength, mixes whichare too stiff to be compacted by hand compaction can be easily compacted bymechanical compaction, in case the concrete is compacted by vibrations , duringwhich the vibrator communicates rapid vibrations to the particles, increases thefutility of concrete.Due to vibrations, the particles occupy a more stable positionand concrete fills all the space.

Types of vibratorsFollowing are the type of vibrators usually used to compact the concrete:

1. Internal vibrators

2. External vibrators

3. Surface vibrators

4. Vibrating table

Internal vibrator consists of metal rod like vibrating head which is immersed in thefull depth of concrete layer. It is also known as poker or needle vibrator and isconsidered as most effective type of vibrator as it comes in to intimate contactwith concrete. External vibrators are placed against the concrete foamwork andvibrating force for compaction is conveyed to the concrete through the foamwork. These vibrators are also called form vibrators. The vibrator is rigidly


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clamped to form work resting on an elastic spot, so that both the form andconcrete are vibrated.

Concrete Mix DesignThe process of selecting suitable ingredients of concrete and determining their relativeamounts with the object of producing a concrete of the required strength, durability, andworkability as economically as possible, is termed the concrete mix design.

Types of Mixes

Nominal mix

In the past the specifications for concrete prescribed the proportions ofcement, fine and coarse aggregates. These mixes of fixed cement aggregateratio which ensures adequate strength are termed nominal mixes.

Standard mix

The nominal mixes of fixed cement aggregate ratio (by volume) vary widely instrength and may result in under or over rich mixes. For this reason, theminimum compressive strength has been included in many specifications. Thesemixes are termed standard mixes.

IS 456-2000 has designated the concrete mixes into a number of grades asM10, M15, M25, M30, M35, M40. In this designation the letter m refers to themix and the number to the specified 28 day cube strength of mix in N/mm2.

Designed mixes

In these mixes the performance of the concrete is specified by the designer butthe mix proportions are determined by the producer of concrete, except that theminimum cement content can be laid down. This is the most rational approach tothe selection of mix proportions with specific materials in mind possessing moreor less unique characteristics. The approach results in the production of concretewith the appropriate properties most economically.


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Factors affecting the choice of mix proportions

The various factors affecting the mix design are:

1.Compessive strength

The compressive strength required at a specific age, usually 28 days, determinesthe nominal water cement ratio of the mix.

2.Workability

The degree of workability required depends on three factors. These are size ofthe section to be concreted, the amount of reinforcement, and the method ofcompaction to be used. For the narrow & complicated section with numerous

corners or inaccessible parts, the concrete must have a high workability so thatfull compaction can be achieved with reasonable effort.

3.Durability

The durability of concrete is its resistance to the aggressive environmentconditions. High strength concrete is generally more durable than low strengthconcrete. In the situations when high strength is not necessary but the conditions

of exposure are such that high durability is vital, the durability requirement willdetermine the water cement ratio to be used.

4.Maximum nominal size of aggregate


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In general, larger the maximum size of aggregate, smaller is the cement requiredfor a particular water-cement ratio, because the workability of concrete increaseswith in size of the aggregate.

5.Grading and type of aggregate

The grading of aggregate influences the mix proportions for a specifiedworkability and water cement ratio. Coarser the grading, leaner will be mix whichcan be used. very lean mix is not desirable since it does not contain enough finermaterial to make the concrete cohesive.

Design mix for M40(for 1cum-concrete)

Water 154kg

Cement 440kg

Fine agg. 627kg

Coarse agg. 1182kg

20mm 709kg

10mm 473kg

Design mix for M30(For 1 cum concrete)

Water 168kg

Cement 390kg


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Fine agg. 683kg

Coarse agg. 1131kg

20mm 679kg

10mm 452kg


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ACKNOWLEDGEMENT

.

JKPCC is one of the leading construction corporation in J & K. It was a greatexperience to be a part of this esteemed organization as a trainee. During this shorttraining of 6 weeks, I have been guided by many staff members here at the site. I amhighly thankful to all the staff to have taken the time off from their busy schedule forexplaining each and every minor detail. First and foremost, I am highly obliged to DGM ,JKPCC UNIT-12 for permitting me to actually join the training, and his constantsupervision due to which I have come a long way in building a sound practicalknowledge. Next, I would like to thank managers who gave me vital details about theproject, relating it to the theoretical concepts and also gave me inputs on how to

manage things for optimal output owing to their vast experience, and their timely inputsand checks have actually helped me go into every detail of the project.

I am very much thankful to Mr. khurshid sb (AEE/Civil), Mr. (jEE/CIVIL), and otherswho very selflessly gave me all the details of the construction methodology, and wouldtake out their valuable time to answer all my queries. They have really guided me allalong the project and have taken pains so as to make this training period worthwhile forme.

Last, but not the least, I would like to thank all the JKPCC (Contractor) members andstaff at the site for their cooperation


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PROJECT OVERVIEW

Name of Work :Construction of district hospital at anantnag

Owner: R & B division anantnag

Project Consultant: Structural & Geotechnical consulttants

Estimated Cost: 61 crs

Contractor: JKPCC

No of stories : G+3

Coverd area: 50,228 sft

grade of concrete: M25

steel reinforcement used : 10 mm, 25 mm


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IMPORTANCE OF PRACTICAL TRAINING:

Engineering science is quite different from other academic studies, and thebiggest cause of difference is importance of its practical field .

The main aim of practical training is to make students aware of the practicalhappenings.The academic course of civil engineer is meant to learn fundamentals andknow how to apply results of these basics on practical problems.

INFORMATION REGARDING PROJECT:

The hospital consists of 300 beds and is being accomplished by JKPCC in districtanantnag of kashmir valley to serve the people of that region.it also includes the modernfacilities not found in other hospitals.

LOCATION OF PROJECT:

The hospital was located in anantnag and is going to serve Not only the people of thatdistrict but the othert districts too.it has easir connectivity with far flung areas ofanantnag and also with other districts like pulwama,shopian and kulgam.


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ESTIMATED COST AND PERIOD OF COMPLETION:

The cost of the project was estimated to be about 61 crore rupees but no

deadline was given to working company.The construction of bridge started in november2007,the construction is going on smoothly and is expected to be completed very soon.

IMPORTANCE OF THIS PROJECT:

It will reduce the load on the existng hospital and will provide the better medicarefacilities to the people. its construction will reduce the rush of the patients to the existing

hospital and will increase its capacity.its latest design and facilities avaliable will servefor the betterment of people.

SITE SAFETY RULES

Manager/Engineer/Supervisors Responsibilities at the site

-Understand the companys and clients saf ety plan fully and follow the same in their

day to day work activities.

-Be familiar and show commitment to the implementation of our companys Health &Safety Plan.

-Ensure that all persons undergo Health & Safety training before they are deployed atthe site.

-Ensure that employees working under them implement relevant requirements of thissafety plan

-Giving safety instructions to their workmen on a daily basis as a part of the jobinstructions, highlighting the possible hazards of the days work and t he precautions tobe taken.

-Ensuring that the technicians under them are issued with necessary PPEs and theyuse the same.


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-Identify weakness and deficiencies in job procedures, rectified these if possible andwhere necessary refer these to the Project Manager / Safety Representatives.

-Keep their work area neat and clean, especially at heights free from loose materials

-Promote the continuous improvement of Health & Safety performance.-Verifying the third party test certificates while hiring cranes of any lifting appliances fortheir validity.

-Preventing horseplay of workmen.

-Organizing and conducting tool box talks to their workmen every day.

-Identifying and eliminating all unsafe conditions in their respective work area bycarrying out safety inspection every day.

-Take suitable corrective measures to rectify the unsafe observations pointed out bysafety Engineers in his inspection report.

-Inform their Respective Manager & Safety Representatives about ACCIDENT, NEAR-MISS & FIRST AID Case.

SITE SAFETY RULES

OPERATIVES

-Make sure you attend a site safety introduction prior to commencing work.

-Safety Helmets, High visibility vests and safety footwear are mandatory on site.

-Possession and consumption to Alcohol/drugs is prohibited.

-Smoking prohibited at work areas.

WORK AREAS


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-Do not cross barriers or no entry areas.

-Keep your work area clean, tidy and maintain good housekeeping.

-All openings should be covered.

-Scaffolding only to be erected dismantled or altered by an authorized competentperson.

-Use ladder, never climb on scaffolds.

-Never remove guard rails.

-Never tamper with Electrics.

-Only authorized person should operate electrical power tools.

UNPLANNED EVENTS

-Report all accidents including near misses.

-Know the best means of escape from your work area and your assembly point in caseof emergency.

-Use proper fire extinguisher to extinguish the fire.

PLANT & EQUIPMENT

-Only authorized operators and drivers should operate plant/equipment /vehicle.

-Always use the right tool for the right job.

GENERAL

-Follow safety signs, instructions and site safety rule.

-Inform your supervisor, if something is in unsafe in your activity.


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-Never carry out any operations, which may cause danger or injury to any person orloss of property.

WE TAKE PRIDE IN EVERYONE RETURNING HOME SAFELY EVERYDAY

SAFETY IS THE RESPONSIBILITY OF EVERYBODY

BE SAFE ALWAYS

GO FOR ZERO ACCIDENT

CONSTRUCTION PROCESS

Construction process undergoes by this series.

1. Site clearance & decommissioning

2. Demarcation of site

3. Positioning of central coordinate & layout

4. Excavation

5. Plain cement concrete

6. Water proofing

7. Layout of foundation

8. Column erection

9. Beam and slab

Site Clearance & Decommissioning - Site clearance means removing all the buildingsand facilities from a site. It might also include ground remediation where soil has been


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contaminated radiologically or by other agents. Decommissioning is the process relatedto decontaminating and removing buildings or other structures; and clean up isconcerned with ground remediation of contaminated land. Site clearance is, therefore, acombination of decommissioning and cleans up.

Demarcation of Site- The whole area on which construction is to be done is marked soas to identify the construction zone. In our project, area was chosen and the respectivemarking was done. The marking is done on bases of points given by surveyors.

Positioning of Central coordinate and layout- The centre point was marked with the helpof a thread and plumb bob as per the grid drawing. With respect to this center point, allthe other points of columns were to be decided so its exact position is very critical.

EXCAVATION

Excavation was carried out both manually as well as mechanically. Normally 1-2 earthexcavators were used for excavating the soil. Adequate precautions are taken to seethat the excavation operations do not damage the adjoining structures. Excavation iscarried out providing adequate side slopes and dressing of excavation bottom. The soilpresent beneath the surface was too clayey so it was dumped and was not used forback filling. The filling is done in layer not exceeding 20 cm layer and then itscompactedThe excavation is done by excavators and the excavated soil is transportedby truck.

Drawings Required

1. Centerline Drawing

2. Layout Plan

Removal of Excess Soil


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Estimate the excavated stuff to be re-utilized in filling, gardening, preparing roads, etc.As far as possible try to carry excavation and filling simultaneously to avoid doublehandling. Select and stack the required material in such a place that it should notobstruct other construction activities. The excess or unwanted material shouldimmediately be carried away and disposed off by employing any of the followingmethods.

Departmental labour.

Tractor.

Trucks.

QUALITY CHECKS FOR EXCAVATION

Recording initial ground level and check size of bottom.

Disposal of unsuitable material for filling.

Stacking suitable material for backfilling to avoid double handling.

Strata classification approval by competent authority.

Dressing bottom and sides of pits as per drawing with respect to centerline.

Necessary safety measures observed.

QUALITY CHECKS FOR FILLING

Recording initial ground level

Sample is approved for back filling.

Necessary marking/ reference points are established for final level of backfilling.

Back filling is being carried out in layers (15cm to 20cm).

Required watering, compaction is done.

Required density is achieved.

PLAIN CEMENT CONCRETE (P.C.C)

After the process of excavation, laying of plain cement concrete that is PCC is done. Alayer of 75mm was made in such a manner that it was not mixed with the soil. It


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provides a solid base for the raft foundation and a mix of 1:4:8 that is, 1 part of cementto 4 parts of fine aggregates and 8 parts of coarse aggregates by volume were used init. Plain concrete is vibrated to achieve full compaction. Concrete placed below groundshould be protected from falling earth during and after placing. Concrete placed inground containing deleterious substances should be kept free from contact with such aground and with water draining there from during placing and for a period of sevendays. When joint in a layer of concrete are unavoidable, and end is sloped at an angleof 30 and junctions of different layers break joint in laying upper layer of concrete. Thelower surface is made rough and clean watered before upper layer is laid

Materials and Tools used

Auto level instrument

Wooden /Steel rammer

Mixer machine

.

WATER-PROOFING

The moisture present in the ground or rain water may penetrate into the building frombelow, from side and also sometimes from the top of its roof, causing the structure toremain in damp condition and thus deteriorating the structure as a whole. It is therefore,very essential to prevent any moisture penetrating into a building now-a-days, care istaken while designing and constructing any building so that dampness can be preventedfrom affecting it and its inhabitants.

There are various methods of water-proofing but at our site Kota stone with grouting isused as water-proofing because they are very impervious.

METHODS OF WATER-PROOFING

After laying P.C.C (100 mm thick) first we clean the surface by the help of blower.

After cleaning the surface the cement sand mortar is prepared.

We add 1 liter. Siko in 1 bag cement and the same is applied in 25 mm thicklayer.


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Then Kota stone is laid in cement mortar (1:4) (25 mm thick).

After laying Kota stone gap between stone and P.C.C is filled with slurry.

And then 25 mm protection coat of cement plaster is applied.

KOTA STONE IS USED AS WATER-PROOFING MATERIAL BECAUSE

1. It is impervious to moisture.

2. It is durable.

3. It does not disintegrate under loading.

4. It provide uniform and homogeneous layer.

5. It is easily available.

LAYING OF FOUNDATION

At our site, isolated square foundations are used to spread the load from a structureover a large area, normally the entire area of the structure. foundations are used todistribute heavy column and wall loads across the entire building area, to lower thecontact pressure compared to conventional spread footings.Isolated foundations areused where the load expected from superstructure is not heavy enough .

METHOD OF LAYING OF FOUNDING

First we study the drawing.

After study the drawing B.B.S. (BAR BENDING SCHEDULE) is prepared by theengineer.

Then the B.B.S. is passed at senior level.


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After B.B.S. is passed reinforcement is prepared by reinforcement gang at steelyard with the help of bar bending machine, bar cutting machine etc.

When reinforcement is prepared it is taken to the site (at working place) with thehelp of tractor, tower crane, manually.

Then formwork is prepared for foundation by carpenter gang.

Then the reinforce bar is tied as per drawing specifications by reinforcementgang under supervision of engineer.

Cover blocks are providing at bottom, sides and ends of foundation of 50mm.

After completing the reinforcement it is checked by the senior officers.

When the reinforcement is passed, we ready for next step of concreting.

Concrete Grade used in foundation: - M30

COLUMN ERECTION AND CONCRETING

Concrete columns are used for carrying loads of a building. They transfer the

same to a suitable soil bearing capacity. They carry loads horizontally, vertically andlaterally. They can be erected as free standing, used for hanging gates. Alternativelythey can be incorporated within the walls of a building structure. Concrete columns aremade from steel and concrete cast in a formwork. These are done in circular,rectangular or square shapes.

METHODS OF COLUMN ERECTION:

In erecting concrete columns the load to be carried is considered. Thisdetermines the size of column and type of reinforcement to use.

After that surveyor give us some point for starter of column. Then the starter isprovided as per points.

Formwork of the required column size is formed first aside.

The steel should be free from oils and rust. Use binding wire to tie together allsteel. Its important to cast concrete in lifts. This should not exceed two thousand five


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hundred millimeters in height. When the steel work is complete, then form workassembly starts.

The formwork for erecting a column is fixed by opening the sides. Its then slid tohave the steel inside the box. Once the box is upright, the form work is then fastened

and supported on all sides.

Concrete is then poured and vibrated until it reaches the top of the box. It is leftfor seven days.

Curing is done from the top. After seven days the form work is then removed toexpose the cast column.

This is continuously cured for another seven days.

COLUMN REINFORCEMENT


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TIE BEAM REINFORCEMENT

CARE TAKEN WHILE COLUMN ERECTION

A proper tie of reinforcement is done.

Lap length should by according to drawing.

Cover blocks are provided at suitable intervals.

Board used should not be in damage condition.

Staging should be done properly.

Alignment should be proper.

BEAM AND SLAB CASTING

MATERIALS AND MACHINERY USED

mixers.

Vibrators

REINFORCEMENTIt shall be as per BBS prepared according to approved drawing. The R/F shifting

and binding shall be started as soon as shuttering is completed. R/F binding shallcontinue as formwork and shuttering work is progresses.


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PRODUCTION AND PLACEMENT OF CONCRETE

Stock of material shall be sufficient to start the concrete. It shall be ensured bystores/purchase dept that concreting is not stopped on account of materials.

All plant and machinery are checked and made in working conditions.

Proper walkways/platforms shall be arranged so that the supports of the pipeline andmanpower are not directly stand on reinforcement.

Sufficient carpenters along with supervisor shall inspect the behavior of supports belowthe slab during the casting. Extra Props shall be stocked below slab to provideadditional supports in case of any failure of supports.

CURING

The curing shall be started immediately after thumb set of the concrete laid. Final curingshall be done by ponding and stacking water for minimum period of 7 days.

SCAFFOLDING

Scaffolding is a temporary structure used to support people and material in theconstruction or repair of buildings and other large structures. It is usually a modularsystem of metal pipes or tubes, although it can be made out of other materials. Bamboois still used in some Asian countries.

The purpose of a working scaffold is to provide a safe place of work with safe accesssuitable for the work being done.

SHUTTERING


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Shuttering or form work is the term used for temporary timber, plywood, metal or othermaterial used to provide support to wet concrete mix till it gets strength for self support.It provides supports to horizontal, vertical and inclined surfaces or also provides supportto cast concrete according to required shape and size. The form work also producesdesired finish concrete surface.

Shuttering or form work should be strong enough to support the weight of wet concretemix and the pressure for placing and compacting concrete inside or on the top of formwork/shuttering. It should be rigid to prevent any deflection in surface after layingcement concrete and be also sufficient tight to prevent loss of water and mortar formcement concrete. Shuttering should be easy in handling, erection at site and easy toremove when cement concrete is sufficient hard.

Generally there are three types of shuttering.

Steel Shuttering Wooden Planks Shuttering

Temporary Brick Masonry Shuttering

WOODEN PLANK SHUTTERING:-

Generally wooden planks shuttering is used by contractors because this shuttering ischeap and easily available. But this type of shuttering affects the strength of concreteand has some disadvantages which are given below.

DISADVANTAGES

This is not water tight shuttering as the size and thickness of planks differ andare not of same size. Due to this difference the water and cement flow to the groundfrom joints and reduce the strength of concrete.

Bottom level of RCC slab is not in straight line and the surface being uneven, thethickness of plaster is more which remains weak.

Due to leakage of cement slurry through joints, earth work below 'Ballies maysettle and create problems.

In some cases wooden planks cannot bear the weight of concrete. Due to lowstrength there is bending or deflection in wooden planks. Sometimes the planks maybreak.


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PRECAUTIONS FOR VERTICAL SUPPORTS FOR RCC BEAMS, SLABS ETC

The 'Ballies used for vertical support should not be less than 6'' dia and theseshould be in one length without joints.

Never allow bricks support of more than one or two bricks below a 'balli' to makerequired height.

Cross Ballies or bracing should be done for better support to beam as well asslab.

The wooden batten used below the plate should not be less than 5'' in height.

At the time of concreting one carpenter with helper having spare ballies, nails etc.should be deputed for watching any disturbances in ballies under shuttering.

REMOVAL OF SHUTTERING

As a guideline, with temperature above 20 degree following time limits should befollowed:

STRUCTURAL COMPONENT Age

Footings 1 day

Sides of beams, columns, lintels, wall 2 days

Underside of beams spanning less than 6m 14 days

Underside of beams spanning over 6m 21 days

Underside of slabs spanning less than 4m 7 days

Underside of slabs spanning more than 4m 14 days

Flat slab bottom 21 days


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importance of practical training 9

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