dbemanual (english)

8/12/2019 DBEManual (English)

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DETAILED BRIDGE SURVEY

MANUAL


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Project : Highway Maintenance Management System GulfClient : Ministry of Transport, Kingdom of Saudi Arabia Engineering House

CHAPTER 1i


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CHAPTER 1iii

Preface

The purpose of this manual is to provide guidelines for personnel

responsible for Detailed Bridge Evaluation Survey of distress bridges on

Kingdom's Highway System. This manual is prepared as part of the

Highway Maintenance Management System Project commissioned

by the Ministry of Transport (MOT) & in association with Gulf

Engineering House (GEH) and to be carried out by the Detailed

Bridge Evaluation Team of GEH for comprehensive study of distress

condition of bridge elements. The manual is designed to provide the

Bridge Engineers the probable cause of distress, proper knowledge of

detailed bridge evaluation and testing procedures as well as

rehabilitation strategies to be taken on defects elements. Prioritisation

of maintenance work and repair methodology is also included in

rehabilitation strategies chapter. In addition to the above execution

specification requires during the restoration time is also furnished inthis manual. The manual is based on the Highway Maintenance

Management System manual.


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CHAPTER 1iv


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CHAPTER 1v

TABLE OF CONTENTSItems Page no

CHAPTER 1 Introduction 1 - 2

(a) Background

(b) Objective

(c) Purpose

(d) Review of Inventory Data

CHAPTER 2 Inspection Activities 3 - 11

(a) General

(b) Inspec tion Team

(c) Inspection Aids

(d) Inspection Equipment

(e) Testing Guidelines

CHAPTER 3 Test Manual 13 - 20

(a)

CAPO Test

(b) BOND Test

(c) RCT Test

(d) Relative Humidity Test

(e) Crack Mapping

(f) Ultra-sonic Test

(g) Carbonation Test

(h) ECP Test

(i)

Covermeter Test(j) Break-up Test

CHAPTER 4 Evaluation Procedures 21 - 40

(a) General

(b) Evaluation of Distress

(c) Sample Photographs

CHAPTER 5 Rehabilitation Strategies 41 - 60(a) General

(b) Remedial Measures


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CHAPTER 1vi

(c) Preventive Measures for Future

(d) Prioritisation of Maintenance Work

(e)

Repair Methodology

CHAPTER 6 Standard Forms & Formats 61 - 67

(a) Condition Rating Matrix, Form CRM

(b) Detailed Inspection Form, Form DIF

(c) Check List Form, Form CLF

(d) Quantity Take-off Sheet, Form QTS

(e) Observation Sheet, Form OS

(f)

Photo Log Sheet, Form PLS

CHAPTER 7 Technical Papers & Journals 68 - 125

REFERENCES 126


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CHAPTER 11

CHAPTER 1: INTRODUCTION

(a) Background

Bridges provide a critical link for transportation systems and economic growth. In the

Kingdom highway network system there are more than 4500 bridges. During the past few

years, significant increases in legal loads as well as growth in the volume of traffic and

reductions in resources for bridge maintenance have contributed to the deterioration of

many of the bridges in the Kingdom of Saudi Arabia.

Based on the requirement of Highway Maintenance Management System it is necessary to

employ an in-depth inspection program which covers the detailed inspection of selected

bridge elements & prepare remedial action plans. In order to effectively evaluate the

structural elements, mechanical & electrically operated equipments are to be engaged

followed by a conc lusive result formulation. This in-depth inspection is to be supplement by

relevant test results. A uniform reporting system is essential in evaluating correctly and

efficiently the condition of a structure, determining the rehabilitation strategies, formulating

the test results and finally provides the evaluation report.

The manual provides guidance regarding the way of inspection is to be carried out and

give information about several techniques involved for bridge deterioration findings, type of

damage & its causes and the bridge engineering concepts. It describes how inspection isto be planned and the equipment & plant needed. Working procedure in the field

comprising measurements and sampling are described from planning to completion.

(b) Objective

The objective of this inspection manual is to train inspection personnel and to develop

their competence in order that the quality requirements regarding bridge inspections

should be satisfied. The manual describes the way of inspections as an entity should be

performed and provides guidance in this respect. Also it will enhance the knowledge

about cause of distress and the structural need requires time to time. Furthermore it is a

valuable aid in establishing maintenance priorities and replacement priorities and in

determining structure capacity and the cost of maintaining the structures.

(c) Purpose

The purpose of this in-depth inspection is to

1. Establish a scientific approach towards detailed testing investigation on the bridge

elements existing in the highway network for which the Ministry is responsible

2. Assess the mode of severity of structural elements which may affect the function of

the structure or traffic safety in long term


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CHAPTER 12

3. Provide the information to determine which structure requires maintenance work

and which needs major rehabilitation

4. Furnish the methodology of remedial measure for different distress condition

5. Develop the prioritization factor involved as part of the Highway Management

System

(d) Review of Inventory Data

The investigation will be based on data collected through visual inspection of the

different components of the bridges existing in the Highway network system. The

inventory data collec ted by the Contractor Engineer shall be reviewed randomly toestablish a consistent inventory report. Based on the existing condition reflecting in the

inventory table a detailed evaluation survey is to be performed. The selection of such

survey can be preferred if the following factors are observed.

1. Existing condition of the bridge elements are in a venerable state

2. Mode of severity is not identified and structural impact is not estimated correctly

3. Bridge is carrying excessive load due to increase in traffic volume at present

4.

Ascertain the existing strength of structure from widening point of view


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CHAPTER 23

CHAPTER 2: INSPECTION ACTIVITY

(a) General

The following are the main activities which the inspection teams are expected to perform

as part of the detailed bridge evaluation procedure:

1. Condition assessment which warrants minor structural repair

This activity includes the evaluation of structural components that exhibits minor

deterioration and the preparation of a report & recommendations addressing such

deterioration. Sufficient details, estimated quantities and method of repair will also

be prepared.

Typical type of defects and deterioration that are considered minor in nature and

will be noted as part of this activity are:

Leaking and repair of bearing

Movement in the approach slab

Roadway deck potholes

Minor concrete Spalling

Crack in Non-critical areas

Minor corrosion in steel elements

Erosion of soil slopes

Minor scour at footings

Slope failure near the bridge site

Damaged railing or guardrails

A report will be submitted describing the defects, its likely causes and

recommended remedies along with measured quantities, estimated costs and

detailed information on the standard forms and formats.

2. Condition assessment which warrants major rehabilitation

This activity includes the evaluation of structural component that exhibits major

defects and deterioration with possible safety related implications and the

preparation of a report and recommendations addressing the situation. This will be


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CHAPTER 24

initiated as a result of the findings of the detailed bridge evaluation. The activity must

proceed only when the inspector recognises the defects are too extensive and

minor maintenance actions are not effective to upgrade the structural condition.

Typical defects and deterioration which may initiate are:

Damaged bridge joints warranting replacement

Uncontrolled movement of bearing system

Severe corrosion of bearings

Major concrete distresses

Cracks in critical elements

Severe corrosion in steel members

Fatigue cracking in steel members

Failure in back wall

Extensive deterioration of abutment

Movement or settlement of pier & abutments

Foundation settlement

Impact damage on structural elements

Any combination thereof warranting major rehabilitation

This activity will be accomplished through the following spec ific steps:

-

Obtain sufficient information during visual inspection to evaluate the need for

major rehabilitation of the deteriorated bridge elements. The collected data

from the visual inspection such as problem type and location, safety relation,

dimension and measurement, sketches and photos as well as inventory data will

be evaluated by Ministry of Transport (MOT) in assoc iation with Gulf Engineering

House (GEH) and decision to be taken as to whether to proceed with this

activity.

- Upon acceptance of MOT, as-built plans, design computations and standard

design criteria will be obtained along with any other pertinent data relating tothe design, construction and maintenance of the structures from the MOT.


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CHAPTER 25

- Conduct in-depth inspection of the deteriorated structural elements.

-

Prepare report outlining the findings of the in-depth inspection as it relates to therehabilitation of the structure. For concrete structures whose as-built plan are not

available, a request will be made in the report to conduct field load test to

determine the capacity of the structure and field tests (destructive e.g., core tests

or non-destructive e.g., rebound hammer or ultrasonic techniques) to determine

existing elements condition. For all other structures a format for load capacity

analysis will be suggested.

- Upon approval of the MOT, perform all load and other testing, if required and

undertake structural analysis of bridges to determine load capacity.

- Prepare a report outlining the results of the structural investigation. The report will

include the recommendations to restore, if possible, the structure to its original

loading capabilities or demolishing the structure. In both the case method and

procedure along with necessary drawings, specification and all information will

be provided to enable a contractor to undertake the work.

(b) Inspection Team

(i) Team Composition

The detailed bridge survey team that inspect, test and evaluate the damage

condition of structural elements included in the scope of work shall be composed as

follows:

Bridge Engineer

Technician

Equipment Operator

Driver

(ii) Task & Responsibility

Inspection team should consist of individuals with proper training in bridge testing

and the ability to perform precise examination of structures in any environment and

condition. A qualified inspector must know the basic design criteria, distress pattern,

handling the equipment for testing and evaluate the elements and its structural

impact in future. A good inspector also must be able to prepare concise, specific,

detailed, quantitative and complete notes and sketches in the field in order to

prepare a through in section report at a later time.


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CHAPTER 26

The primary responsibility of the Bridge Engineer is to maintain public safety; therefore

a thorough inspection must be performed to identify defects in details, testing on the

structural elements for distress findings followed by an accurate documentation ofthese deficiencies as well as its remedial measure. The test data must be included

with the final bridge evaluation report which helps to establish and maintain a

structure history file to identify and assess bridge repair requirements and

maintenance needs. The inspector must be on guard for minor problems which can

be corrected before they can lead to major repairs.

(c) Inspection Aids

The inspection team will be given the following information to aid in the inspection process:

1. A map showing the area within the Kingdom where they will be performing

their inspection. The map will indicate the route numbers of all highways

which the team will travel to perform the surveys.

2. A list of inventory and condition survey data for locating the element which

undergone a defects. The list will serve as a guide for field testing and cause

of distress.

3. Sketches or photos obtained from visual survey

4. Sufficient additional data like maintenance history, note sheet and rating

forms to decide on the appropriate course of action

(d) Inspection Equipments

The standard tools which will be used for the inspection are as follows:

Sl. No. ITEM DESCRIPTION

1 Snooper

2 Sky J acker

3 Steel ladder4 Drill Machine

5 Capo Test Instrument

6 Bond Test Instrument

7 Covermeter

8 Hum-meter

9 Half cell Potential Meter

10 Rapid Chloride Test Apparatus

11 Pundits Ultra-sonic Testing Apparatus


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CHAPTER 27

Sl. No. ITEM DESCRIPTION

12 Digital camera

13 Crack measuring Template14 Safety & First aid tools

15 Measuring tape

16 Marking crayon

17 Binocular

18 Thermometer

19 Wire brush

20 Paint Box

21 Schmidt rebound hammer

22 Traffic safety tools

All the instruments used for detailed bridge inspection are to be kept in a mobile

laboratory van. For the testing of bridges, the underside of the superstructure will be

examined by the use of ladder, sky J acker or Snooper type vehicle. In situations where

access to the underside of the superstructure is possible from ground, ladder will be used

for low clearance bridges and Sky Jacker will be utilised for higher structures (height up

to 12m). On those bridges where access is not available from below (i.e., structures in

mountainous region and height is above 12m) a Snooper vehicle capable of reaching

underneath from the road way surface will be used.

(e) Testing Guidelines

The inspector shall have a good knowledge about the testing procedure. The detail

bridge evaluation should be carried out in three competent ways,

1 How to carry out the available methods of testing in practice, including the

operation of the equipments

2. How to select the right type of test method and the test location for

different types of damage

3. How to formulate the test results

The test methods can be divided into three categories which are non-destructive,

destructive and laboratory analysis respec tively.

The Non-destructive survey methods are applicable where the defects are not in an

alarming stage and which needs only minor repairs. The destructive methods are used

where structural behavior of the elements are not known and the location is critical as

per whole structure is concerned. The laboratory analysis, which applied on the samples,

provides detailed and prec ise information about a specific cause of concern.

Generally, the combination of all three categories leads to very reliable conclusions on

mechanisms of deterioration, causes and the extent of damage. In most of the cases


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CHAPTER 28

the first two categories of test are satisfactory to conclude upon the type and extent of

damage.

When the visual bridge inspection is completed, a Hypothesis for the cause of damage is

prepared and based upon those test methods and the location of the test will be

selected. All the data of the visual inspection must be registered and the test data to be

recorded on standard forms attached to the detailed inspection report. Recording of

data must refer to the unique system of numbering the elements of the structure.

When a ll planned tests are completed, the visual registrations and test results must be

evaluated to see if it serves a sufficient basis for concluding the cause, extent, and

possible development of damage. Otherwise, supplemental test must be chosen and

performed. If the test results do not confirm the hypothesis of cause of damage, the

hypothesis must be revised. It may be necessary to perform supplementary test.

Sl. No. Material Test Equipment

Compressive Strength CAPO Test Instrument

Tensile Strength BOND Test Instrument

RCT Test RCT Test Apparatus

Relative humidity Test Hum-meter

Delaminating test Hammer

Crack width Template Gauge

Homogeneousness Pundits Ultrasonic tester

1. Concrete

Carbonation Test Rainbow Indicator

ECP Test Half cell potential meter

Measurement of steel diameter Vernier calipers

2. Steel

Steel cover Covermeter

TEST PLAN CORROSION PROBLEM IN DECK WITH OVERLAY/WEARING COURSE

SELECT AT RANDOM ATLEAST 2 DAMAGED AND 1UNDAMAGED AREAS TO CARRY OUT

1. BREAK-UP THROUGH THE OVERLAY IN EACH AREA2. CHLORIDE PROFILES IN EACH AREA

3.

RH % MEASUREMENTS

EVALUATE THE NEED OF1. CUTTING OF CORES2. CAPO TEST (3 IN DAMAGED & 3 IN UNDAMAGED AREAS)

CARRY OUT ECPMEASUREMENTS

FINAL REPORT

EVALUATE THE NEED FOR FURTHER BREAK-UPS TO ENLARGETHE SIZE OF THE TEST AREA


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TEST PLAN CORROSION PROBLEM IN BEAMS, GIRDERS AND DECK WITH NO OVERLAY

SELECT AT RANDOM APPROXIMATE 10% OF DAMAGEDAND 10% UNDAMAGED AREA. CARRY OUT ECPMEASUREMENTS

RANK THE AREAS ACCORDING TO THE ECP MANUAL. INBOTH DAMAGED AND UNDAMAGED AREA CARRY OUT

1. BREAK-UP2. CHLORIDE PROFILES

3.

RH % MEASUREMENTS

CORROSION ACTIVITY OR RISK OF CORROSION IN THEUNDAMAGED AREA

ENLARGE THE SIZEOF TEST SAMPLES.CARRY OUT ECPMEASUREMENTS

EVALUATE THE NEED FOR FURTHER BREAK-UPS IN THE

DAMAGED AREAS

FINAL REPORT

EVALUATE THE NEED OF CAPO TEST, IF NEEDED, AT LEAST 3IN DAMAGED AND 3 IN UNDAMAGED AREAS


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CHAPTER 210

RANK THE COLUMNSACCORDING TO THE ECP

MANUAL AND MAKE THENECESSARY NUMBER OF BREAK-UP TO CONFIRM ECPMEASUMENT

SELECT AT RANDOM 1 COLUMN,CARRY OUT

1. BREAK-UP2. CHLORDE PROFILE ABOVE GROUNDAND 1m BELOW

DAMAGED

COLUMN

ECP MEASUREMENT ONALL COLUMNS

FOR 2 COLUMNS CARRYOUT CHLORIDE PROFILE

TEST PLAN CORROSION PROBLEM IN COLUMNS

UNDAMAGED

SELECT AT RANDOM 5COLUMNS, CONDUCT

ECP MEASUREMENT ONTHE COLUMNS

FINAL REPORT


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CHAPTER 211

HYPOTHESIS FOR THE CAUSE OF DAMAGE

VISUAL INSPECTION CORRECTION OF THE HYPOTHESIS

MEASUREMENT OF THE REMAININGPART OF ELEMENT

ASSESSMENT OF CORROSION ACTIVITY

CARBONATION TEST

ECP MEASUREMENT

EVALUATE THE NEED FOR1. CAPO TEST2. CORE CUTTING

DETERMINATION OF AREAS

REQUIRING INVESTIGATION

MEASUREMENT OF COVER

BREAK-UP TO CONFIRM ECPMEASUREMENT

DAMAGE MECHANISM

FINAL REPORT

FUTURE RISK OFCORROSION

CONDITION OF CONCRETE

FINAL ASSESSMENT OF THE CONDITION AND RECOMMENDATIONFOR REHABILITATION MEASURE

DETERMINATION OF AREASREQUIRING INVESTIGATION

MOISTURECONTENT

CHLORIDECONTENT

CORE CAPO MICRO MACRO


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CHAPTER 313

CHAPTER 3: TEST MANUAL

The different types of test are as follows:

(a) CAPO Test

In general concrete compressive strength can be measured in-situ by CAPO test. With

CAPO test an 18mm hole is drilled perpendicular to a plane surface outside

reinforcement disturbance with a water cooled diamond bit. A router undercuts a 25mm

hole 10mm deep in a depth of 25mm from the surface. The folded ring is inserted in the

hole and expanded on a special tool in the undercut hole. The hydraulic equipment is

attached to the tool and activated by hand. Pull-out takes place until the CAPO test

failure occurs and the cone is fully dislodged. The cone hole may be repaired with a

polymer modified mortar.

The complete test equipment for CAPO test is contained in two small potable briefcases.

C100 CAPO test equipment

It consists of three units (a) drill unit, (b) milling cutter unit and (c) expansion unit.

Use of the C100 kit requires water supply and electrical or hydraulic power supply.

For these purposes following mobile equipment is available:

C151 water tank, C152 plastic tube and C153 electrical power supply

C105 pull machine

This precision light weight model with high pressure oil-rings are made of special

alloys corrosion resistant and manufactured with highest accuracy. Hydraulic

operated it only requires an easy hand pressure to reach maximum pull out force

at 60 Kn. The instrument accuracy is below 0.3% and the loading of pull force is

automatically governed by a special built-in valve system. Normally supply

gauges are filled with shock absorbing glycerin and have a range from 10 to 70

MPa.

In addition to the above C11O CAPO inserts are also available which can be reused two

or three times.

(b) BOND Test

It is only used for measured the tensile strength. Normally, the method is primarily used for

testing the bond strength of a newly cast concrete layer to the existing concrete. Further

it can be used for testing the tensile strength of the existing concrete surface when

certain strength is required before the new concrete layer and /or water proofing can


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be placed. Finally it can be used for testing the bond of a membrane to a concrete

surface. Before the standard testing procedure reinforcement is located and the test

location is selected. The top part of the surface is ground smooth and plane. Dust isremoved with a steel brush and a steel disc 75mm diameter is glued to the surface with

a quick setting epoxy. The CORECASE 75mm assembly is placed with the drill bit fitting

exactly around the steel disc and fastened to the surface by means of two clamping

pliers anchored to the concrete. Drilling takes place to a required depth using water as

a cooling media. The drill assembly is removed leaving the core standing perpendicular

to the surface. A counter pressure id fitted around the disc and center by means of a

centering piece. The pull machine is secured to the disc resting against the counter

pressure. Pulling takes place to failure of the weakest part of the core.

The peak load in kN pull force is calibrated to tensile strength or bond strength in MPa

from the calibration table following the equipment and the position of the failure is

recorded. Normally the minimum required tensile or bond strength is 1.5 MPa. Minimum

number of tests is five in a 10m x 10m area. If the basic material is sound and the bond

surface has been prepared by hydro demolition followed by sand blasting, the BOND

strength may be as high as 3.0 to 3.5 MPa. The normal BOND test deviation of uniform

bonding layers is about 5%.

The BOND-TEST equipment is supplied in three suitcases containing

Preparation kit for BOND-TEST

Six 75mm in diameter steel discs with thread (reusable)

GERMANNS rapid adhesive, box with component epoxy for non-acrylic

concrete or membrane

One set of two component Araldite for acrylic base concrete

Counter pressure, adjustable with Allen key

Centering piece

620 W grinder with carbide bit stone

Steel brush

CORECASE 75mm standard

Drill assembly, mechanical feed handle, coupling, water jacket with flange

containing rubber gasket

Standard diamond drill bit, 75mm in diameter 120mm long


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Two pairs of clamping pliers

Anchoring tools

Water dive pump

Pull Machine

Automatic type pull machine

Coupling

Pull bolts

Bolt handle

(c) RCT Test

The Rapid Chloride test, RCT, provides a fast method of determining the acid soluble

amount of chlorides of concrete in situ.

Powdered concrete obtained by hammer drilling of hardened concrete is mixed with a

chloride extraction liquid and shaken for five minutes. The amount of acid soluble

chlorides expressed as weight percent of concrete weight is determined directly bymeans of a calibrated chloride sensitive elec trode connected to the RCT electrometer.

Taking more samples at different depths in the same location usually in steps of 30mm,

60mm, and 90mm the Chloride profile is determined by testing each depth interval.

Examining the profile, the probable source of the chlorides and mechanism of

penetration can be detected.

The RCT test measures bonded as well as free chlorides, because the concrete sample is

dissolved in an acid that frees the bonded chlorides. An assessment of the content offree chlorides can be made by carrying out the measurements in distilled water instead

of in the acid. The free chlorides will rapidly be dissolved in the water, while the bonded

will remain bonded.

The RCT equipment is contained entirely in a suitcase containing

Chloride sensitive elec trode type RCT

Elec trometer, digital readout with pH measurement option

Calibration liquids (clear, purple, green and pink)


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10 RCT-1023 testing vials for hardened conc rete

Hammer drill

400mm long 18mm twist drill

Dust collec tion pan & tools

Weight measuring ampoules

Calibration chart

(c) Relative Humidity Test

The test method measures the relative humidity in the pores of the concrete (usually the

outer 100mm. a 16mm hole is drilled into the area to be tested and a plastic sleeve,

which has a thin membrane enclosing one end, is inserted into the hole and left for

approximately one hour. This provides enough time for equalization of both relative

humidity and temperature. The test is conducted by breaking the enclosed end of the

sleeve with the probe of the measuring device, and recording the values.

(d) Crack Mapping

Mapping is normally used to provide an overview of the damage and for registering the

extent of damage. Investigation of structural crack pattern must be mapped indicating

the type (bending, shear) and corresponding extent distress. For Non- Structural crack

patterns, the areas must be mapped and the assume cause to be noted.

Spalling, scaling and rust/ rust stains should be indicated by area. Splitting cracks due to

corrosion must be mapped. When mapping specific cracks, Characteristic widths are

measured with a scale and the location indicated as a supplement to the visual

inspection of the surface. Regarding both structural and nonstructural cracks, the risk of

corrosion in the future should be evaluated. If there is a risk of corrosion, it should benoted in the report. When corrosion damage to the reinforcement bars observed, note

the reduction in cross sec tion area in percent of the undamaged cross sec tion.

(e) Ultra-sonic Test

This test is performed to check the homogeneity of the material. Sometimes material

density in one part of the structure is not similar to the other part; in that case 50 KHz

ultrasonic unit is place on both the surface and measurement to be taken. If the

concrete surface is porous or having a sign of honeycombing the structural strength is

reduced due to insufficient density and for that particular circumstance ultra-sonic

technique is playing a key role to determine its density. The method used in this test is to

induce an ultra ray on the concrete surface and check the traveled time to the other


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face as well as percentage of absorbance.

(f)

Carbonation Test

This test is performed by applying an indicator solution to concrete surface just fractured.

The color of the solution will change with corresponding changes in PH of the concrete.

The carbonation depth is then measured by means of a scale.

The two different indicator solutions are available in the mobile laboratory van are

Phenolphthalein (1%) - after application, the color of the alkaline concrete surfaces will

immediately turn red-violet indicates ph>9.5 & carbonated surface will remain colorless.

Rainbow Indicator - this solution, when applied, will produce a series of colors

corresponding to various ph levels, again distinguishing the alkalinity of the fractured

concrete surface.

(g) ECP Test

The purpose of the potential measurements is to map the electrochemical potentials in

order to locate areas with risk of corrosion. The potentials are measured either by the

path finder equipment or an ordinary multi-meter (voltmeter) and a referencing

electrode.

Following steps are to be followed.

1. Exp osure of a reb a r for the elec t rica l c onn ec t ion

Normally go for stirrup locations. The most convenient areas are where the cover

often varies or on the edge beam

2. Che c k the c i rc ui t of the reinforc em ent

On columns, make a contact to the reinforcement of another column to check

the circuit by using the multi-meter. The potential differences must be zero to

have the circuit required. If that is the case, use the same connection during the

whole measuring. If the difference is not zero, first of all check the connection to

the rebar. If this connection is good, the internal connection of the reinforcement

is not sufficient and you have to make a contact to every column on both sides

of the joints.

3. Ma ke a m ea suring gr id on ea c h pa rt to be m ea sured , not ing the fo l low ing

When making survey measurements on large areas, a mesh size of 500X500 mm

may be chosen. Prior to making the grid, survey measurements on large areas,


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random locations may help locating the areas to be mapped. When making

measurements in areas where corrosion is likely to occur (selected as a result of

survey measurements, experience or other test types), the mesh size must be250X250mm or less. The grid size, location and orientation must be marked on

sketches of the structure. If the measurements are started in the upper left corner

of the grid and made one horizontal row at a time. The print out from the

pathfinder equipment will have the same orientation as the grid.

In many cases, e.g. on columns, it is more convenient to measure in vertical rows.

In this case, start at the lower left corner of the grid and make the measurements

of a vertical row from the bottom and upwards. Proceed to the right to the next

row (i.e. counterclockwise on the columns). In this case the print out must be

rotated 90 degrees counterclockwise to get the correc t orientation.

4. Che c k the stab i li ty of the p oten t ia l m ea surem ents

- Wet a single measuring point

- Place the electrode and note the potential measurements:

- Wait until the potential is stable. Note the potential and time .this time

difference is the necessary time required between the wetting and the

measuring. In very dry concrete, it is normally necessary to wet

continuously for a longer period. This means that one person is constantly

wetting the structure in front of the person doing the measuring.

5. Selec t ion of the test a rea a nd ev a luat ion of c orrosion

It should be noted, that the potential measurement itself does not lead to a final

assessment of the condition. Supplementary testing has to be carried out. As a

first guide to an evaluation of the reliability of the measured potential values, the

measurements are normally divided into phases.

Immediately after completing the measurements, the measurements are printed

out on the printer and then evaluated according to a scale based on

experience, e.g.

Group-1 x>0 mv No corrosion

Group-2-200mv


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spread with evident corrosion signs on the bars

in some cases on the concrete too.

Note: use colors to distinguish between the groups, e.g.

Group-1 White

Group-2 Green

Group-3 Yellow

Group-4 Red

The above mentioned limits are based on measurements with a silver/silver chloride

electrode. If using another electrode, limits have to be corrected according to the

following table.

Type of Electrode constant

Copper Sulphate -80mv

Calomel -75mv

Local corrosion which does not cause Spalling of concrete cover shows lower potentialsthan general corrosion with expanding rust products.

(h) Covermeter Test

The Covermeter is used to locate the reinforcement in the structure and to measure the

depth of the concrete cover. The Covermeter is often used to locate the rebars before

starting other investigations such as ECP measurements, core drilling, capo test,

inspection of cables etc.

The Covermeter measurement is based on changes in the magnitude field lines/eddycurrent. The presence of nearby magnetic rebar will cause changes, which can be

measured by passing the measuring head over the surface above the rebar.

This measuring head is a rectangular encapsulated unit containing the search coil. As

the coil windings are directional, the head should always be used with its longitudinal

axis parallel to the expected line of the reinforcing bars. A lead from the head is

plugged into the battery operated Covermeter.

This method is generally suitable. Test has shown that the inaccuracy increases from 5-

10% at approx. 35mm depth to approx. 15-25% at 60-70%depth.

(i) Break-up Test


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A break up is a hole in the structure, made in order to see the condition of the interior

parts. Break ups provide in most cases a necessary supplement.

1. To register the general configuration of the concrete

2. To register the type of reinforcement, dimension, position and possible

corrosion damage

3. To provide a reference level for the electro-chemica l potential (ECP)

measurements and to calibrate the measured corrosion activity indicated

by the ECP Measurements.

Break-ups are also necessary in cases where the concrete surface in consideration is notvisible because of the wearing course or in similar cases. Break-ups are a common part

of special inspection of concrete structures and usually performed with the help of

power tools. The back side of exposed rebar can be inspected by the use of a convex

lens or a dental mirror.

When performing the Break-up test take care not to weaken the structure to harmful

extent. The structure should be re- established immediately after making break-ups.


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CHAPTER 4: EVALUATION PROCEDURES

(a) General

The evaluation procedures for bridges are presented in the following sequence: first the

structural component is described then the expected deficiencies are listed. The data

available through visual inspection and investigation have been analyzed to ascertain the

state of safety and condition of the structure. The reasons for damage to the components of

the bridges have been investigated and analyzed in the context of establishing remedial

measures. Based on above, the description of the component and expected deficiencies

noticed in the different components of the bridges has been taken up.

The bridge is divided into three primary groups: superstructure, substructure and

miscellaneous. The superstructure includes the expansion joint, the deck slab, the bearing,

the primary member and secondary member. The substructure includes the piers and the

abutments. In case of piers, it includes the pedestal, the cap beam, the column or wall and

the footing. In case of abutments, it includes the pedestal, the breast wall, the back wall,

wing wall and the footing, where as in case of miscellaneous part, it includes the wearing

surface, the railing/parapet, the side walks and the utility services. In this report the

presentation of the rehabilitation measures are given sequentially from the top part to the

bottom part of the bridge: starting from wearing surface to footing.

(b) Evaluation of Distress

1. Asphalt Wearing Surface

The top most layers or course of material applied upon the structural deck to provide

a smooth riding surface is the wearing surface. The wearing surface also serves the

function of protecting the deck from the effects of traffic, weathering and chemical

action. Prior to the placement of asphalt surface, a water proofing membrane is

usually installed to protect the concrete deck surface.

Common defects of asphalt wearing surfaces consist of cracking, distortion and

disintegration.

Cracking in asphalt surfaces can take many forms.

Alligator cracksare interconnected and forming a series of small blocks resembling

an alligators skin or chicken wire. It is generally caused by excessive deck deflection

or by the asphalt material drying out.

Edge cracksare transverse cracks near the edge of the deck, usually due to lack of

lateral support, the drying out of the asphalt or deterioration of the concrete deck.


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Lane joint cracksare longitudinal separations along the seam between two paving

lines, usually caused by a weak seam between adjoining asphalt pavement

applications.

Reflective cracksare observed in asphalt overlays which reflect the crack pattern in

the underlying deck.

Shrinkage cracksare interconnecting cracks forming a series of large blocks; it is

often difficult to determine whether the cracks are caused by volume change in the

asphalt or cracking of the underlying deck.

Slippage cracksare crescent shaped cracks caused by the lack of a good bond

between the surface course and the deck beneath.

Distortion can be defined as any change of the surface from its

original shape. Most frequently encountered types of distortions are:

Ruttingare channelized depressions which usually develop on bridges along a wheel

tracks of an asphalt surface. It may result from consolidation or lateral movement of

the surface under traffic.

Corrugation & shovingare a form of plastic movement typified by ripples across the

asphalt surface, usually occurring in asphalt surfaces that lack stability. It may appearas crescents with the curved portion pointing in the direction of traffic as in slippage

cracks or as actual bumps transverse to the direction of travel.

Grade depressionsare localised low areas of limited size which may or may not be

accompanied by cracking. These defects also referred to as birdbaths are not only

a source of surface deterioration but are a hazard to motorists especially in areas

and seasons that freezing weather is to be expected.

Disintegration is the breaking up of a surface course into small loose

fragments. The two most common types are:

Potholes are bowl shaped holes varies sizes in the surface course resulting from

localised disintegration.

Ravellingis the progressive separation of aggregate particles in the surface course. It

is usually the result of poor construction techniques as well as low asphalt content in

the asphalt concrete mix.

2. Side walks

Side walks normally do not contribute to the structural strength of the bridge but may

be an integral part of the bridge by virtue of its construction. It is provided mainly for


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traffic safety. Side walks usually made of concrete or steel present the following

deficiencies:

Impact damage from vehicles

Sign of differential movement at the joints due to horizontal or vertical

movement of the supports

Material deterioration of side walks such as cracks, spalls and

delamination

3. Railing & Parapets

Railing & parapet normally do not add structural strength to the bridge. It should

have sufficient strength to prevent an out of control vehicle from going off the

bridge. Most of the railing in Saudi Arabia is made of concrete or steel. The most

common defects in this type of railings are associated with the same causes listed

under side walks.

4. Drainage System & Utility

Bridge drainage system is an important item and particularly in the areas of Saudi

Arabia where flush flood occur an effective system of drainage that carries thewater away as quickly as possible is essential to the proper maintenance of the

bridge. It is common for commercial and industrial utilities to use a highway right-of-

way to provide services to the bridge structures. These may be one or more of the

following: gas, electricity, water, telephone, sewage and liquid fuels. Almost all of

the drainage problems are caused by the clogging at inlets, corrosion of steel

drainage pipe or entrapped water due to insufficient drainage route. Most utility

lines or pipes are suspended from bridges between the beams or behind the fac ia

resulting spalling at support locations

5. Deck Slab

The primary function of the deck slab is to carry traffic and to transmit the traffic load

to the main structural systems. Bridge deck is particularly vulnerable to deterioration

because it is subjected to direct impact loads, corrosive actions and climatic

conditions. Deck deterioration is of utmost concern to maintenance personnel

because the safety of the travelling public may be jeopardised if the integrity of this

element is not maintained properly. From available bridge statistics nearly 80 percent

of the bridges in the Kingdom are made of reinforced concrete with concrete slab.

Common defects of concrete decks appear in three forms: scaling, cracking and

spalling. Also either independently or in assoc iation with spalling the corrosion of


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concrete deck reinforcement is encountered.

Scaling makes itself evident by a gradual decomposition of the cement paste,beginning at the surface and progressive downward. It may be the result of the

expansive forces due to wet-dry cycles, poor drainage, poor materials, improper

construction or chemicals.

Cracking may be transverse, longitudinal, diagonal or random. Cracking occurs

when tensile stresses exceed the tensile strength of the concrete. There are as many

probable factors causing cracking, as there are types of cracking. Transverse cracks

usually occur over top rebar. Longitudinal cracks are common between pre-stressed

concrete box beams. Random cracks may be caused by load deflection, improper

curing methods, material defects, foundation movements or other related

phenomena.

Spallingis the breaking out of pieces of concrete, often starting at the top reinforcing

steel. It is usually proceed by cracking. Most authorities agree, however, that spalling

is related to the corrosion of reinforcing steel and that spalling is accelerated by the

presence of chlorides. The minimum effect of spalls on bridges is the increased

impact created by vehicles bouncing through the spalled area. Extensive spalling on

concrete deck may actually reduce the safe load carrying capacity of the bridge.

Corrosion of reinforcing steel embedded in concrete is a serious phenomenon

primarily related to the salt contaminated bridge decks. The corrosion of reinforcing

steel embedded in concrete is now recognised as an electro-chemical process. In

order for an electro-chemical cell to be established, there must be an anode and a

cathode electronically connected and contained in an ionic conductor or

electrolyte. If these components are present and if the free energy of the cell

reaction is negative, then a spontaneous electro-chemical reaction will occur. The

intrusion of the chloride ion penetrates the concrete cover of the reinforcing bars

embedded in the bridge deck and destroys the strength of steel.

6. Expansion Joints

Expansion joints are designed to provide for various rotational, translational and

transverse movements of the superstructure under live loading or thermal expansion

and contraction as well as to prevent leakage to the components below the deck.

The most common defects of expansion joints are listed by type. The types examined

are Finger, Strip-seal, Elastomeric and Modular joints.

Finger jointsallow movement with essentially no stress concentration in the joint face

or the deck. Defects assoc iated with this system consist of the following:

Failure of the drainage system causing debris and moisture to fall


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onto the elements of the structural members supporting the deck

Loosening of the beams and angles supporting the expansion devicecausing deterioration of the joint assembly and cracking of the

adjacent concrete deck.

J amming or locking of the joint due to excessive movement of the

superstructure. This action usually causes damage to the concrete

curbs and side walks because of excessive forces being exerted by

the pavement expansion.

Strip-seal joints are one of the most common types of expansion joints. Defects

associated with this joint type consist of the following:

Leakage of joint and deterioration of bridge elements beneath the

joint

Wedging of debris in the joint preventing it from functioning properly

and causing spalling and crushing of joint edges

Loosening of the steel angle supports which is a hazard to motorists

Elastomeric jointis a sealed, waterproof joint system utilizing steel plates and anglemoulded into a neoprene covering. The neoprene serves as a protective cover for

the steel components, a water proof material to prevent water penetration through

the joint system. A cushion between the load transfer plates to prevent traffic

generated noise and due to its elastic properties permits expansion movement of the

bridge superstructure. Defects are usually prevalent with this joint are following:

Water leaking to the superstructure beneath the joint

Wearing of the neoprene material

Popping out of the neoprene plugs covering the anchor bolts resulting

in the corrosion of the bolts and nuts securing the system to the

concrete deck

Failure of the sealant between the outer edges of the joint and the

deck wearing surface resulting in contaminants leaking under the

joint

Loosening of the joint support system due to the impact and vibration

of the superstructure

Modular jointconsist of a heavy duty neoprene gland snap locked into extruded


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steel members which are anchored onto the concrete deck. The defec t commonly

associated with this type of joint is cold weather. In cold weather and at maximum

joint opening, the joint allows for the accumulation of roadway grit and materials inthe joint opening. During warm weather periods and maximum expansion, the joint

can not function properly because of the dirt that accumulated in the joint opening

resulting in spalling of concrete deck edges.

7. Primary Members

Primary members are defined as those structural elements which carry all

superstructure loads to the substructure below. In Saudi Arabia most primary

members are made of concrete. In cases of composite steel bridges the

superstructure consists of steel beams or girders with concrete slabs connected to

them by shear connectors. The common defects found in primary members of the

bridge superstructure are following:

Box beam may develop undetected deterioration of the bottom slab

due to water and chemical leaking of the top slab that cant drain

out. Such box top slab covered by asphalt at top and inaccessible

from bottom.

The beam & stringers of the structures used as overpasses are the most

vulnerable when stuck by over height loads. Damage can vary from

insignificant to large extend.

Cracks are very common in concrete members. It may be structural or

non-structural type. Damage can be spalling or exposed

reinforcement on the concrete surface.

Most common problem in steel bridge element is rust. Corrosion

causes a loss of cross sectional area resulting in a reduced load

capacity of the member.

Steel beams are essentially susceptible to cracking when joints or

connectors are welded or when certain types of design details such

as partial length cover plate sharp re-entrant corners or cantilever

brackets are used. Locations where flange plates change width or

thickness are also problem areas for fracture.

Rolled beam & girder bridges are often used for overpass. This makes

them subject to collision damage from over height loads attempting

to go under the bridge. This damage is often so severe that traffic over

the bridge must be restricted or may even have to be closed.


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8. Secondary Members

Secondary members are defined as those structural elements which aid in thetransfer of superstructure loads to the substructure and reduce the deflection of the

bridge. It is usually constructed of steel and concrete. The common defects

encountered in secondary member of the bridge superstructure are the following:

Failure of bridge drainage systems and deck joints eventually leads to

the deterioration of concrete elements due to the spalling of the

concrete and the eventual rusting of the reinforcing steel.

Exterior diaphragm and struts on overpasses are the most vulnerable

when stuck by over height vehicles.

Most common problem in steel bridge element is rust. Corrosion

causes a loss of cross sectional area resulting in a reduced load

capacity of the member.

Diaphragm and bracing are susceptible to cracking when joints or

connections are welded or when certain types of design details such

as re-entrant corners or cantilever elements are used.

9. Bearings

Bearings are normally used to transmit and distribute the superstructure loads to the

substructure while permitting the superstructure to undergo necessary movements

without developing overstress. The bearings deficiencies are as follows:

Roller bearing is used to transfer vertical loads and allow for superstructure rotation

and translation. The defects prevalent with this type of bearing are most commonly

due to the following causes:

Build-up debris

Loss of protection system such as paint or galvanizing

Corrosion and steel delamination due to corrosive action

Sheared and/or corroded anchor bolts and retainer plates

Disintegration and/or deterioration of the material under or

immediately adjacent to the bearing

Mis-positioning of the bearing during construction or operation in the

form of extension towards the edge, tipping of the bearing and


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CHAPTER 428

misalignment etc.

Rocker bearing is used when either a large vertical load or a large amount ofsuperstructure translation or a combination of the two are anticipated. The most

common defects in this type of bearing are associated with the same causes listed

under roller bearing.

POT bearing is normally used where there is a large vertical reaction, a large amount

of anticipated translation in two directions or a combination of the two. The fixed pot

bearing is constructed of a carbon steel cylinder which confines and seals an

elastomer. Sliding pot bearing is similar in construction to the fixed type except that it

also incorporates the use of Teflon or stainless steel sliding plates to allow for

translation. The defec ts are similar to roller bearing.

Elastomeric bearingis normally used on prestressed concrete or steel girders of short

and moderate span length. These bearing are constructed of neoprene and carbon

steel moulded into a solid void free mass. This bearing is designed to accommodate

both horizontal and vertical movements by the distortion of the bearing itself. The

most common defects found in this type are associated with the following causes:

Build-up of debris

Disintegration of material under or immediately adjacent to bearing

Excess shearing which is normally considered to be longitudinal

displacement of more than 25% of the bearing height

Non-uniform compression at the four corners or twisting of the bearing

Ozone cracking or cuts in the bearing

Failure of the bond between elastomer element and wedge plates

Rounding of the edges of the elastomeric element due to wear

10. Bridge Seat & Pier Cap

This element is top of abutments, piers or bents upon which the bearing rest. Any

deterioration of this section could result in differential settlement of the superstructure

and unplanned stresses. The most common defects of bridge seats and pier caps are

general deterioration of the concrete can be the result of chemical or mechanical

attack, poor aggregates, poor concrete, wet-dry cycle damage or various

combinations of these. The damage is usually in the form of spalling, scaling, pop-outs

or sloughing off at the corners. The depth of the deterioration may vary from

superficial to large extent.


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11. Abutment & Pier

Abutments and piers transfer the loads of the superstructure to the foundation. Thedefects usually encountered in abutments and piers are the following:

Settlement or movement

Vertical cracking caused by differential settlement

Surface deterioration cracking etc

Back wall undermining

Impact hit by passing vehicles or floating debris

12. Water Channel

The streamed bed and the banks of wadi in Saudi Arabia although not filled with

water are subjected to flash flood that may have more damaging effects than those

of river flow. Such flash floods are more dangerous in the coastal areas of the

Kingdom. The most common defects found in stream bed and banks are following:

Erosion may undermine the substructure and may cause differential or total

settlement.

Depositionmay cause the restriction of flow at the bridge site and potential damage

of the superstructure. As flash flood depositions are also assoc iated with the

accumulation of debris, the restricted flow causes flood water to rise at the level of

the superstructure and cause damage.

(c) Sample Photographs

Sample photographs include each distress element photo covering the appearance and

extent of defects, close-up view during testing time and type of testing is carrying out on the

elements. All photos are to be logged on standard forms for better control. These typical

sample photos are taken from previous database of HMMS.


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Core cutting process is carrying out

Positioning of core cutter on the concrete deck


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CHAPTER 431

Core is extracting from the concrete deck

Extracted core sample to be used finding compressive strength


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CHAPTER 432

C100 CAPO test equipment & its accessories

Hole is drilled by diamond bit


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Insertion of folded ring into the hole and fastening the head

Pull-out the core by milling cutter unit


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CHAPTER 434

Core sample has been extracted by milling cutter

CAPO test location has been marked by paints


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CHAPTER 435

Break-up test has been performed

Applying rainbow indicator for carbonation test


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CHAPTER 436

Test location has been cleaned for carbonation test

Carbonation test has been performed at breast wall bottom


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CHAPTER 437

Reinforcement section is measuring by Vernier calipers

Grid lines are mapped for ECP test by Half Cell Potential Meter


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CHAPTER 438

ECP test is carrying out on cantilever slab

Mapping of cracks by crayons


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CHAPTER 439

Width of crack is measuring by crack template

Slab panel reinforcement is corroded and severe spalling is observed


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CHAPTER 541

CHAPTER 5: REHABILITATION STRATEGIES

(a) General

The corrective actions on bridges are normally divided into two categories: remedial

(action taken after the deficiency has occurred) and preventive (action taken to prevent

the deficiency). In this chapter rehabilitation strategies for bridges are presented in the

following sequence: first the remedial measures of each distress are illustrated and then the

preventives for each deficiency in future are described.

The remedies and or preventive measures to be adopted can avoid untimely

damage/distress of the structure. Accordingly, repair proposals have been framed keeping

in view the following aspects.

- To bring back the structures to the original design values of safety and serviceability

- Cost effectiveness and least time consuming with latest know how of materials and

construction technology indigenously available

- Causing minimum disturbance to the traffic

(b) Remedial Measures


The remedial actions for asphalt surface defects mentioned in the previous chapter

are as follows:

Alligator and slippage crack repair involves removal of the surface course down to

the deck and laterally into the sound surface course. Make the cut square or

rectangular with faces straight and vertical. To repair the deck first apply tack coat

to the exposed deck and vertical faces. Patch with a dense graded plant mix hot

asphalt and compact to the same elevation as the surrounding surface. To repair

edge, lane joint and reflective cracks, clean out cracks with stiff bristled broom and

compressed air. Fill with emulsion slurry or liquid asphalt mixed with sand. When

cured, seal and treat with liquid asphalt and sprinkle the surface with saw dust or dry

sand to prevent pick-up the traffic. Shrinkage crack repair should fill cracks with

asphalt emulsion slurry followed by a surface treatment or slurry seal over the entire

surface.

Prior to channel and grade depression repair, determine the limits of channels or

depressions with a straight edge. Apply a light tack coat and spread dense gradedasphalt concrete in the channels with a paver. Be sure that the material is feathered

at the edges. Compact with a pneumatic tired roller and then place a sand seal


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CHAPTER 542

over the area to prevent the seepage of water. Corrugation and shoving should be

repaired similar to alligator cracks.

Potholes should be repaired similar to alligator cracks. To correct ravelling, sweep the

surface free of all dirt and loose aggregate. Apply a fog seal of asphalt emulsion.

After the seal has cured apply a surface treatment.

2. Side walks

The remedial actions recommended for repairing the side walks are the following:

The loss of structural ability will be restored depending on the type of distress found

(crack, deterioration, loss of section and reinforcement corrosion). Materialdeterioration of side walks will be restored (cracks, spalls and delamination). The

differential movement at the joints may require as simple a remedial action. Impact

damage will be restored as required.


The remedial measure apply on raining is same as side walks. In addition to the

above yielding fender system is used near the bridge abutment. Stuck fender system

shall be restored either by partial or total replacement. The damage portion of a

yielding fender system must be repaired or replaced otherwise the system can notbe expected to function properly.


For the drainage system and utilities the following remedial actions are

recommended:

Most effective remedial action is the cleaning and flushing of the drainage system

particularly from wind blown sand accumulation and debris. Corroded metal pipe

must also be replaced and restored to the extent required. Short scupper pipes

must be extended so as to prevent drainage from blowing onto bridge members.

The maintenance team must report to relevant authority for proper maintenance

as required. Loose or suspended utility lines must be restored to a safe operating

state until the agency responsible for its maintenance assumes its full restoration to

sound condition.

5. Deck Slab

The remedial actions for the scaling, cracking, spalling and corrosion of

reinforcement of concrete deck are described as follows:


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Scaling, where it occurs may be corrected by using a thin epoxy mortar patch to

the waterproof the area and prevent penetration of water to the reinforcing steel.

Quick setting cement as well as low slump and high cement content are alsoadaptable for this repair.

Crackingof concrete deck is corrected by evaluating whether to repair a cracked

or not and the method of repair depend on the nature of the crack. Where stresses

are relieved and a stabilised condition exists, crack may be repaired simply injecting

low viscosity epoxy mortar. The detailed repair methodology is discussed in

subsequent paragraph.

Spallingcan be corrected by patching, overlays or replacement. For small spalled

areas, polymer modified concrete and non-shrink cement mortar can be used as

deck patching. Somewhere along the patching process a decision is made to cover

the entire deck bottom with a durable overlay which will serve as a moisture barrier.

The most important objective of using an overlay must be to exclude water from the

deck, of all the factors contributing to the deterioration of deck, water is the most

important factor. Dissolved oxygen in the water set up an oxidation process which

leads corrosion in reinforcing steel. Based on the economical point of view

sometimes replacement is the other alternative of overlay which gives more

durability and less maintenance cost in future.

Corrosionof reinforcing steel can be prevented by cathodic protection. Cathodic

protection via the use of electro-chemical techniques insures that oxidation

reactions do not occur at the reinforcing steel. This is accomplished be embedding

in the concrete deck a supplemental anode in the form of a metal mesh which is

capable of sustaining oxidation reactions without suffering any physical damage.

The anode is connected to the positive terminal of a power supply and the

reinforcing cage to become cathodic to stop oxidation.

6. Expansion Joints

The remedial measures associated with the expansion joints are as follows:

Finger jointrusting should be regularly cleaned, repaired or replaced based on the

existing condition. In addition, frequent flushing of all exposed horizontal surfaces

beneath the joint opening to remove accumulated debris will prevent rusting of

steel support members. If the expansion device is loose, repairs can normally be

accomplished by removing the loose or faulty bolts, repositioning the device and

bolting. If the adjacent deck concrete is broken, damaged concrete should be

removed and replaced with a low shrinkage concrete mix. If the joints are broken, orlocked then relieve the pressure at the joint location, if any and remove the entire

joint system and reinstall.


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CHAPTER 544

Strip-seal jointleakage problem can be repaired by removing the debris form the

joint opening and install a preformed compression joint sealant to water proof the

joint. Flush all contaminants from the bridge elements beneath the joint. If localisedcrushing of the deck edges has occurred open deck joints can be readily repaired

by removing and replacing the damaged concrete.

Elastomeric jointleakage and damage can be repaired by replacing the neoprene

material. Areas with loose anchorage or broken bolts can be repaired by removing

broken bolts and re-establishing the joint device using the J bolts instead of

expansion anchor bolts.

Modular jointsealants that have been whipped out of the joint by traffic may be

repaired by cleaning all debris from the joint opening, repairing the joint edges, if

needed and installing a new sealant. If an accumulation of debris in the joint

opening has resulted in transverse movement of the deck, then repositioning of the

deck should be accomplished or provision be made to prevent additional

movement.

7. Primary Members

The remedial actions to be applied to primary members of the bridge superstructure

are the following:

Exposed reinforcement in lower slab of concrete box girder can be repaired by

partial depth cement repair to re-bond the loosened reinforcing bar. If repair

procedure requires the unbonding of a ll bars, it is obvious that false work will be

required under the structure while the repair is in progress.

Concrete T-beam or stringer can result in significant damage due to over height

vehicles. Usually surface need only be patched with high grade concrete to restore

proper cover. Cracked beam with no broken reinforcement can usually be repaired

by epoxy injection. There are various methods available for repair of cracks inconcrete. Application of these methods depends on the cause of cracks, extent

and location of cracks.

Concrete structures can also be externally strengthened by adding reinforcing

plates, stitching reinforcing bars or post tensioning.

Any crack or fracture in a steel beam should be considered a sign of serious distress

and immediate remedial action must be taken. If the crack is large or in a critical

location, it may be necessary to restrict or even close the bridge until the member

can be replaced.


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CHAPTER 545


The remedial action to be applied to secondary members of the bridge

superstructure is similar to the primary member.

9. Bearings

For Roller bearing,the following remedial actions are recommended:

Clean off debris frequently to prevent build-up

Clean and repair the deteriorated protection system in accordance

with accepted painting or galvanizing procedures

If corrosion is severe enough to prohibit the bearing from functioning

properly, bearing replacement will be necessary and needs

temporary support system for jacking up the superstructure

Replace sheared or heavily corroded anchor bolts and retainer

plates if shearing is taken place

Remove defective concrete from under and around the bearing and

replace it with new

Appropriate MOT unit must be notified if unusual movement or stress

cracks are observed

Where bearing is immobilised, clear the bearing and the area around

the bearing. Repair or replace the protective system. Lubricate the

bearing, if appropriate.

ForRocker bearingthe same remedial action recommended.

For POT bearing the same remedial action recommended.

ForElastomeric bearingthe following remedial actions are recommended.

Clean the debris to prevent build-up

Remove defective material from under and around the bearing and

replace it with new.

For problems relating to excess shearing, non-uniform compression,

ozone cracking, bond failures and excessive wear, no immediate

corrective measure must be taken unless there is danger of collapse.

The appropriate MOT unit must be notified to conduct a study of the

condition which would include the probable cause of the situation.


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CHAPTER 546

10. Bridge Seat & Pier Cap

The remedial actions for bridge seats and pier caps are the followings:

Where deterioration has occurred under the bearing temporary bents must be

erected that will transfer the load of the superstructure off the bearing.

All rust and deterioration must be removed by sand blasting or chipping. Any

significant loss of section must be replaced by plating with welds. The surface must

then be primed and the best coatings available applied. Fractured welds must be

chipped away and replaced with high quality welds. Loose or broken rivets and pins

must be removed and replaced.

11. Abutment & Pier

For the abutments & piers the following remedial actions are recommended:

Settlement problem should be determined and corrected. This could be due to

inadequate bearing capacities of the supporting soil or due to subsurface sliding.

Vertical cracking caused by differential settlement can be corrected by sealing with

epoxy mortar or shotcrete. If the back wall moved to such an extent as to block the

structural member, demolish and reconstruct the back wall again.

The first step in the repair of concrete deterioration is to completely remove all

defective concrete using various types of air tools. The method of bonding the new

concrete to the old will depend upon the depth and volume of the repair. Using

shotcrete method for bonding of new concrete to the old has favourable results.

The loss of soil adjacent to the back wall is usually caused by a deteriorated deck

joint which is allowing roadway drainage to enter behind the back wall and wash

the soil away. The problem can be solved by replacing the joint after back filling

behind the wall and compacting as required.

12. Water Channel

For the stream bed and bank defects the following remedial actions are

recommended:

Where erosion is experienced, carefully map the affected area and determine the

extent through a scour analysis. Based on the above analysis, determine the

earthwork volume or requirement of gabion baskets, rip-rap or concrete lining to

restore the stream bed to its original shape.

Deposition is somewhat associated to erosion. However, when found, it requires


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CHAPTER 547

removal and transportation of soil or debris to areas beyond the active wadi bed.

(c)

Preventive Measures for Future


The early detection and repair of minor defects in asphalt surface is the most

important part in bridge rehabilitation. Cracks and other defects, which in its

initiation phase are almost unnoticeable, may develop into serious defects if not

repaired early. For these reason frequent close inspection of the wearing surface

should be made.

2.

Side walks

The following preventive measures are recommended for side walks:

The loss of structural ability and material deterioration may be prevented by good

construction technique and control of overweight vehicle.

Impact damage may be mitigated by providing adequate lateral clearance and

sufficient curb and sidewalks marking.


The preventive measures for future are similar as side walks.


Frequent inspection is to be performed to check the adequacy of drainage system.

Sometimes painting is to be done to prevent the corrosion of metal pipe. Short

scupper pipes must be extended to prevent drainage from blowing onto bridge

members.

The maintenance team must report in advance to the relevant agencies for proper

maintenance of the utility service to avoid sudden collapse of suspended pipes.

5. Deck Slab

Scaling may be prevented by the use of high quality materials, proper construction

methods and maintaining good drainage especially in the spout areas. A regular

program of flushing the deck may reduce the occurrence of scaling.

Cracking may be prevented by taking the same precaution as spalling. Provisions for

adequate expansion of the approaches will eliminate cracking at the deck joints

associated with pavement thrust. Structural cracking can be prevented by good


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design & construction and avoiding overloads of structures.

Spalling as well as cracking may be considerably reduced by eliminating followingfactors contributing to the corrosion of reinforcement.

Coating of reinforcing bar

Using better and more impermeable concrete

Providing a protective waterproofing system for the deck at the time of

construction

Providing adequate cover over the rebar

Designing properly to reduce excessive live load vibration and deflection

Providing cathodic protection

Using proper construction technique and quality control

Using polymer impregnated concrete

For the corrosion of reinforcement on bridge decks, cathodic protection acts as

both a remedial and a preventive action.

6. Expansion Joints

Finger Joint- An adequate drainage system of sufficient slope which may be easily

cleaned is essential. If the deck kept clean a minimum amount of debris will enter

the drainage system eliminating the need for frequent cleaning. An adequately

designed and adequately anchored expansion device is the best prevention

against looseness of the device or broken expansion fingers. Routine observation

and corrective actions are the best prevention against damage from roadway

vehicles.

Strip seal joint The use of a sealing material such as a poured-in-place

polyurethane joint sealant used in conjunction with a backup material will prevent or

deter the effects of water and debris passing through the joint. However, a program

to reseal these joints on a regular basis is necessary.

Elastomeric joint The most effective prevention for elastomeric joint is close

supervision during the construction phase so that the joint system is properly aligned

and installed as recommended by the manufacturer and warranted by goodconstruction practice.


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Modular Joint Proper installation of the joint material, along with good

maintenance methods after installation will prevent many problems associated with

joint material ravelling, joint spalling, leakage at the joints and transverse movementof the superstructure. Keeping the joint clean and properly sealed to prevent the

intrusion of sand and dirt is the best method of preventing transverse movement of

the superstructure. Once movement has occurred further movement may be

prevented by properly cleaning and resealing the joint and bracketing the span in

place to help resist further movement or by securing the deck to the stringers to resist

transverse movement of the deck with respect to the stringers on the non-composite

structures.

7. Primary Members

The preventive measures to be used for primary members of the bridge

superstructure are the following:

A waterproof membrane on a deck of box girder would prevent water and

chlorides passing through the lower slab. Proper maintenance of hole through the

bottom slab will prevent entrapment of water.

Careful attention should be given to the accuracy and proper placement of

advance warning system of vertical clearance to prevent collision damage of T-

beam or girder.

Extending floor drains below the bottom of beams or girders will minimize the

deterioration of concrete and possible corrosion of reinforcing steel damage deck

drains.

The common method of protecting structural steel from rust and resultant corrosion is

to keep it covered with paint.

A regular program of flushing chemicals from the structure seats, pier tops, lowerflange of through girders and other areas where dirt or debris may collect on

structural members will prolong the life of a paint system. Periodic cleaning and spot

painting of leaky joint areas will also prevent corrosion and prolong its life.

The only feasible method to prevent cracks or fractures is to avoid as much as

possible the use of design details that are likely to cause high fatigue stress. Since

cracks are usually associated with weld, wrong welding must be discouraged

without analysis of stress condition in the beam.


The remedial action to be applied to secondary members of the bridge


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superstructure is similar to the primary member. In addition, all vertical clearances

should be checked after resurfac ing of the roadway below.

9. Bearings

For roller bearingthe following preventive action are recommended:

Have a program to clean dirt and debris off bridge seats at frequent regular

interval

The surface m

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