ACI 345.1R-92(Reapproved 1997)

Routine Maintenance of Concrete Bridges

Reported by ACI Committee 345

Ralph L. DuncanChairman

Donald W. AldenRalph K. BanksClaudius A. CarnegieKenneth C. ClearJohn J. CoriglianoRobert N. DentzPaul Klieger

* Deceased

Committee members voting on 1992 revisions:

John L CarratoChairman

John H. AllenPaul D. CarterRalph L DuncanRobert V. GeveckerRobert J. GulyasAllan C. HarwoodMark R. Heim

Robert V. GeveckerSecretary

Peter MezaHoward H. Newlon, Jr.Orrin RileyWilliam Rohde*Arthur P. SeylerDonald W. Vannoy

Paul KliegerSurinder K. LakhanpalPaul F. McHaleHarry L PattersonOrrin RileyWilliam F. SchoenVirendra K. Varma

Various potential sources of distress and the possible areas affected in theroadway, superstructure, substructure, approaches, slopes, and channel ofa bridge are described Guidance for avoiding or correcting such troublesis also provided in the form of a day-to-day maintenance and preventivemaintenance guide. The report is directed to the local maintenance su-pervisor who has the responsibility for routine bridge maintenance.

Keywords: Bridge decks; bridges (structures): cleaning concrete pavements;control joints; drains; highway bridges; maintenance; slope protection; sub-structures; superstructures.

CONTENTS

Chapter l-Introduction, pg. 345.1R-21.1-General1.2-Preventive maintenance1.3-Scope

ACI Committee Reports, Guides, Standard Practices, and Com-mentaries are intended for guidance in designing, planning,executing, or inspecting construction and in preparing speci-fications. Reference to these documents shall not be made inthe Project Documents. If items found in these documents aredesired to be part of the Project Documents they should bephrased in mandatory language and incorporated into theProject Documents.

345.1

Chapter 2-Roadways, pg. 345.lR-22.1-General2.2-Cleaning and flushing2.3-Deck cracks2.4-Deck treatments2.5-Asphaltic concrete overlays2.6-Expansion joints and devices2.7-Deck drains2.8-Snow removal

Chapter 3-Superstructures, pg. 345.1R-83.l-General3.2-Concrete superstructures

ACI 345.1R-92 supersedes ACI 345.1R-83 effective February 1, 1992. Minorrevisions have been made to the report in 1992. The reference chapter has beenreformatted and the year designation of the recommended references of thestandard producing organizations has been removed so that the current editionsbecome the referenced version.

Copyright Q 1983. American Concrete Institute.All rights reserved including rights of reproduction and use in any form or by

any means, including the making of copies by any photo process, or by anyelectronic or mechanical device, printed or written or oral, or recording for soundor visual reproduction or for use in any knowledge or retrieval system or device,unless permission in writing is obtained from the copyright proprietors.

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3.3-Steel superstructures3.4-Bearings

Chapter 4-Substructures, pg. 345.lR-94.1-General4.2-Routine maintenance

Chapter 5-Roadway approaches, pg. 345.1R-5.1-Pavement expansion joint5.2-Leveling approaches5.3-Approach roadway shoulders5.4-Approach roadway surfacing5.5-Approach roadway gutters5.6-Joints at bridge ends

Chapter 6-Bridge slopes, pg. 345.1R-116.1-Concrete slope protection6.2-Erosion under curb outlets

Chapter 7-Stream channels, pg. 345.1R-127.1-Drift7.2-Brush and vegetation

Chapter 8-References, pg. 345.1R-12 8.l-Recommended references8.2-Cited references

CHAPTER 1-INTRODUCTION

l.l-GeneralA modem highway bridge is a costly, complex struc-

ture. The elements of the structure, from foundation toparapets and railings, must interact with each other in aunique, efficient way. The special features designed toenhance safety and to provide a pleasing overall appear-ance are also important in the service the bridge pro-vides.

The malfunction of one element can affect the overalloperational efficiency of the structure. The movement ofa pier can cause collapse of an entire span; a damagedbearing seat might cause deck failure or collapse of anentire span; a slick deck invites collision of vehicles witheach other or with the bridge parapet or railing.

Experience in highway operation has shown that con-tinuous and systematic maintenance of a bridge will ex-tend its service life and reduce its operating expense.’Nevertheless, maintenance of bridges and their ap-proaches is often the most neglected phase of highwayoperation.

l.2-Preventive maintenanceAs soon as a bridge is constructed and put into ser-

vice, its deterioration begins. The changes that develop

Fig. 2.1-Severe deterioration in the bottom of the deck

Fig. 2.2-Severe deterioration in thetop of the deck

Fig. 2.3-Water saturated concrete

___^, .-

Fig. 2.4-Ponding of water on the deckcaused by dirt in the curb outlets

Fig. 2.5-Ponding of water on thedeck caused by snow

Fig. 2.6-Ponding of water on the deckcaused by inadequate deck drainage

MAINTENANCE OF CONCRETE BRIDGES 345.1 R-3

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are gradual and usually slow, and there is a tendency togive them little attention. The sudden catastrophic eventis the one that demands immediate action. Some of thesedevelopments can be avoided if good systematic, preven-tive maintenance is practiced. Tried and proven practicesof day-to-day maintenance can keep the bridge operatingefficiently. Periodic inspection of all components of thestructure should be made in a careful and systematic wayto locate areas that need attention before they becomemajor repair problem.2 When working around a bridge,time should be taken to check for any potential failures.When a potential failure is observed or suspected, itshould be promptly reported.

1.3-ScopeThis report lists and discusses various potential

problems and the areas that might be affected in abridge. It provides guidance for avoiding and/or cor-recting such problems. It is intended as a day-to-daymaintenance guide for the supervisor who has responsi-bility for routine bridge maintenance. It is not intendedas a manual of repair, rehabilitation, reconstruction, orbridge inspection. This guide should, however, be ofinterest and use to all engineers and technicians in thosefields. Many detailed methods of repairing bridges arefound in References 3, 8, 12, 14, and ACI 546.1R. Guide-lines for conducting bridge inspections are found in Ref-erences 2, 3, 4, 5, and 9. Useful information on the sub-ject of bridge maintenance may be found in these andother references listed in Chapter 8 including ACI 504Rand ACI 201.2R.

This report is presented under the following chapterheadings: Roadways, Superstructures, Substructures,Roadway Approaches, Bridge Slopes, and StreamChannels.

CHAPTER 2-ROADWAYS

2.1-GeneralThe bridge roadway includes the deck, with or with-

out separately applied wearing surfaces, joints, railings,parapets, median barriers, curbs, sidewalks, and deckdrainage systems.3,4

Loose and deteriorated concrete and water-saturatedareas commonly occur on the bridge deck, both top andbottom. Examples of severe deterioration are shown in

ig. 2.7-Water penetrating concrete deck

ig. 2.8-Scaling deck

Fig. 2.9-Spalling deck

345.1R-4 ACI COMMITTEE REPORT

Fig. 2.1, 2.2, and 2.3. Damage of this type is usually theresult of freezing and thawing action on the concrete,corrosion of the reinforcing steel, or a combination of thetwo. Water containing chlorides penetrates the concreteand initiates these actions. Water ponded on the deckaccelerates them.7

Exposed deterioration can be located by visualinspection. Nonvisual damage, such as delaminatedconcrete, can be detected by the hollow sound made bya chain drag or sounding with a hammer.9

2.2-Cleaning and flushing2.2.1 Periodic cleaning and flushing of concrete decks,

drains, expansion joints, lower chords, bent caps, andother elements should be performed.5,10

2.2.2 All drainage devices, such as curb outlets, pipedrains, floor drains, downspouts, etc., should beadequately cleaned to prevent pending of water on thedeck (see Fig. 2.4)5.

Following are two reasons for this:a) Safety-The danger of vehicles hydroplaning or

skidding on ice in the winter (see Fig. 2.5 and 2.6).b) Structural deterioration-Water carrying deicing

chemicals will penetrate the concrete eventually causingdeterioration, especially in the areas of cracks and joints(see Fig. 2.7).

2.2.3 It is usually necessary to use a combination ofshovels, brooms, compressed air, trash pumps, mobilecleaners, or water under pressure to remove the salt-laden dirt and debris which cause or accelerate thefollowing:1,3,5,11

a) Scaling of concrete surfaces (see Fig. 2.8).b) Corrosion of reinforcing steel and subsequent

spalling of concrete (see Fig. 2.9).

c) Deterioration of paint systems and corrosion ofthe supporting members (see Fig. 2.10).

d) Corrosion and “freezing” of the expansionbearings.

A sudden drop in temperature causes the structure tocontract rapidly. With the bearings “frozen,” excessivetensile stresses are transmitted to the concrete under thebearing pad, often causing it to crack along a linethrough the anchor bolts (see Fig. 2.11).

2.2.4 One of the more critical and most commonlyoverlooked problem areas is the lower chord and floorbeam flanges and connections on truss spans. Here, ac-cumulations of dirt, trash, and debris can contribute toconsiderable corrosion and deterioration of truss mem-bers (see Fig. 2.12). Periodic cleaning is necessary topreserve the paint system and to avoid any loss of sectionin the steel members at these points.5

Fig. 2.10-Severely deteriorated paint system

Fig. 2.11-Bentcap damage caused by "frozen" bearing andsudden drop in temperature

2.3-Deck cracks2.3.1 Most concrete decks develop cracks. These

cracks may be either transverse, longitudinal, or random(see Fig. 2.13).3

2.3.2 Roadway moisture, carrying deicing chemicalsinto the deck cracks, can create several problems.7,9

a) The moisture and chemicals cause the reinforcingsteel to corrode. The corrosion products swell or expandcausing the concrete to spall over the reinforcing steel(see Fig. 2.14).

b) The water remains trapped in the crack and freez-ing temperatures or traffic action will contribute to spalldevelopment.

2.3.3 Sealing these cracks with asphalt or othermaterials suitable for the purpose can prevent a con-siderable amount of moisture from entering the cracks

MAINTENANCE OF CONCRETE BRIDGES 345.1R-5

Fig. 2.12-Debris collected on lower chord

Fig. 2.13-Deck cracks

Fig. 2.14-Deck spalls

and thus slow deterioration of the concrete deck (see Fig.2.15).3

2.3.4 Deicing salts in solution can also enter un-cracked concrete by permeating the surface, causing cor-rosion of the embedded steel and subsequent cracking.

2.4-Deck treatments2.4.1 Concrete bridge decks, in many cases, are

treated for protection against the effects of moisture anddeicing chemicals. Prior to the use of any deck treatment,the effect the treatment has on the skid resistancecharacteristics of the surface should be investigated.Commonly, new and existing decks subjected to frequentfreezing and thawing cycling, high moisture, and/orfrequent exposure to seawater are treated with a 50-50mixture of boiled linseed oil and kerosene, mineralspirits, or a similar compound.3,6,7,9 Periodic follow-upapplications are usually required.1

2.4.2 A penetration asphalt surface treatment, orequivalent sealer, may be considered for application oversignificantly cracked or extensively patched decks.3,9 Thetraffic volume, grade, and bridge alignment should beconsidered prior to sealing as these factors greatlyinfluence the successful performance of the seal.

When sealing a bridge deck, the entire deck areashould be covered, including the curb outlets. The areainside the outlet, however, should not be included whenthe coverstone is broadcast on the deck. The coverstonein these areas cannot be rolled, and could restrict thedeck drainage due to material buildup.

Care should be exercised to keep the deck expansiondevices free of sealant material which might interferewith their proper functioning and movement. Any ma-terial which may enter an expansion device should beremoved promptly and completely.

For a short time after application, daily removal ofexcess coverstone from the deck is important to reducewindshield damage and avoid blocking drains. In ad-dition, the excess coverstone should be removed from thesubstructure caps and lower chords of truss spans. Thisexcess coverstone may be reused for scalping and sealingareas around timber abutments and abutment wings orfor sealing gutters at the bridge ends.

2.5-Asphaltic concrete overlays2.5.1 Asphaltic concrete overlays are used on bridge

345.1R-6 ACI COMMITTEE REPORT

Fig. 2.1 5-"Sealed" cracks

decks to provide a smooth riding surface and help reducedamaging impact to the deck. They are also commonlyused as a protective wearing surface for penetrationasphalt, membrane waterproofing systems, or other decksealers. Prior to the use of any overlay or increasing thethickness of an existing overlay, the ability of thestructure to carry the added load should be investigated.

As a rule, however, asphaltic concrete overlays arerelatively porous and, by themselves, do not provide aneffective seal.7,12 2This porosity entraps salt-laden moisturewhich, in the absence of an effective deck sealer, canpromote deck deterioration. As a precautionary measurea multiple-course penetration asphalt surface treatment,membrane, or other deck sealer should always be appliedprior to an asphaltic concrete overlay.

2.5.2 When placing asphaltic concrete overlays, enddams should be provided at expansion joints to protectthe overlay next to the joint and to keep overlay materialout of the joint.

Existing asphaltic overlays on concrete bridge decksshould be inspected periodically for cracking and debond-ing from the concrete.3 A hammer or rod may be used tolocate unbonded areas in the overlay. These areas aremore commonly found along curbs, expansion joints, andat locations where the overlay has cracked. Once located,the overlay in these loose areas should be removed andreplaced.

2.5.3 Attempts should also be made to determine thecondition of the concrete beneath the overlay.9,12 If theconcrete deck is deteriorated, all unsound concreteshould be removed and replaced prior to replacing theasphaltic overlay (see Fig. 2.16). Care should be taken tofinish the concrete patch flush with the existing deck.Dormant cracks in the con-crete should be filled andactive cracks should be sealed with a crack-sealing

material to prevent entry of water.2.5.4 To insure good adhesion, the concrete deck

must be dry and primed with an effective sealer andbonding agent before the asphaltic overlay is placed.Care should be taken to assure that the overlay is tho-roughly compacted.

2.6-Expansion joints and devices2.6.1 Deck joints provide for expansion and con-

traction of the bridge.33The joints may sometimes befilled with a compressible material to keep drainage andincompressibles out of the joint. If these joints shouldbecome filled with incompresibles (dirt, sand, cover-stone, debris, etc.), a concrete deck and/or the girderends may crack or crush when expanding (see Fig. 2.17).In many instances, this causes undue pressure on thesuperstructure bearings, resulting in cracking and spallingof a concrete substructure cap (see Fig. 2.18). On somebridges, especially concrete spans built on a skew, thiscondition may cause transverse movement of the deckwith resultant curb offsets obstructing traffic (see Fig.2.19). Debris filled joints may also collect moisture anddeicing chemicals which can deteriorate the adjacentdeck.

2.6.2 Expansion joints - Filled expansion jointsshould be periodically cleaned of all incompressiblematerials. Before replacing joint filler, it should bedetermined whether there is need to do so since changedconditions may dictate otherwise.

Possible replacement joint materials include asphalt-impregnated felt or polyurethane foam topped withpoured-in-place rubber asphalt, polyvinyl chloride, poly-sulfide, neoprene, butyl rubber, or polyurethane?’

2.6.3 Steel expansion devices - To assure freemovement, steel expansion devices should be kept cleanand free of incompressible materials.3

In some cases, flat plate expansion devices close dueto the abutments moving. This movement results in con-siderable pressure on both the abutment backwall andthe expansion device anchorage in the ends of the deck,and could lead to failure in either of these areas. Topartially alleviate this condition, the flat plate may betrimmed, thus relieving pressure. Steps may have to betaken to relieve the pressure which caused the abutmentmovement.

2.6.4 Elastomeric expansion devices - In recent yearsconsiderable attention has been given to the developmentof sealed and watertight joint devices that will expandand contract with bridge movements.13 An elastomericdevice, usually consisting of neoprene and metal, is onesuch type being used on many newer bridges. These de-vices are vulnerable to snowplow damage, particularly ifthey are not designed and/oranchorage of these deviceschecked to ensure no sectionsbecome traffic hazards.

installed properly. Theshould be periodicallyhave worked loose and

2.7-Deck drains

MAINTENANCE OF CONCRETE BRIDGES 345.1R-7

Fig. 2.16-Unsound concrete removed

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Fig. 2.17-Cracked deck girder end

Fig. 2.18-Concrete pulled off of bent cap

ig. 2.19-Offset in curb line caused by deck movement

. “‘.

Fig. 2.20-Debris in deck drain

345.1R-8 ACI COMMITTEE REPORT

2.7.1 Bridge deck drainage systems should be keptclear of debris and functioning to avoid ponding waterwhich can lead to vehicle hydroplaning or skidding onice. Continued ponding also promotes rapid concretedeck deterioration. Stoppages often occur when itemssuch as bottles, cans, and other rubbish accumulate at, orlodge within drains (see Fig. 2.20).3,10

2.7.2 Drains discharging directly beneath the deck canusually be cleared with common equipment. However,more elaborate drainage systems may require specialtools and equipment.10

2.7.3 Drainage discharging onto supporting membersshould be directed away from these members (see Fig.2.21).

Fig. 2.21-Deck drainage directed away from pier cap

2.7.4 Decks with no drains, or those suspected ofhaving an insufficient number, should be observed shortlyafter a rain for areas of ponding water. Such areas shouldthen be marked where additional drains are warranted.Round pipe drains are normally installed where thedeepest water stands.5 Care must be exercised in locatingthese drains to avoid drilling holes through concretegirders or steel stringer flanges, or allowing the dischargeof water onto roadways underneath (see Fig. 2.22 and2.23).

The pipe should be recessed into the deck and shouldbe long enough to direct water away from structuralmembers.10 After the pipe is installed, a mortar should beused to grout around the opening to fill any existingvoids. Damage to the top and bottom of the deck result-ing from the drilling operation should also be repaired.

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Fig. 2.22-Deck drainage directed away from the roadwayunderneath the bridge ig. 2.23-Deck drainage directed away from stringer

2.8-Snow removalCare should be exercised when plowing snow on

bridges. Some bridges have elastomeric expansion jointdevices which are easily damaged by snowplows, whileothers are skewed to roughly the same degree as thesnowplow, which causes a jolt to the driver and damagingimpact to the truck and the bridge if the snow plowdrops into a joint.3 Care should be exercised to preventplow damage to the curbs, parapets, railings, and jointsealant systems.

CHAPTER 3-SUPERSTRUCTURES

3.1-GeneralThe superstructure component includes main mem-

bers, the floor system, secondary members, and bearing

MAINTENANCE OF CONCRETE BRIDGES 345.1R-9

elements.3,4 Main members are those whose failure wouldresult in collapse of the structure, including concrete,steel or timber girders, truss chords, diagonals, and ver-ticals. Floor systems include members which transmitloads from the roadway to the main members. Failure ofthe floor system members would usually have only localeffects. Secondary members add stiffness to the mainmembers. Bearings are the mechanical devices whichtransfer the loads from main members to the substruc-ture and also allow for longitudinal and/or rotationalmovements of the main members.

3.2-Concrete superstructuresIn concrete superstructures, attention should be given

to any serious cracks or spalls (see Fig. 3.1). These de-fects may be indications of structural distress and couldallow water and deicers to penetrate to reinforcing steeland cause corrosion. Such areas should be sealed by theuse of an appropriate grout or patching compound.3

Fig. 3.1-Cracked concrete girder

3.3-Steel superstructuresFor most steel superstructures, other than those of

weathering steel, it is essential that the integrity of theprotective coating system be kept intact.3 Areas wherethe prime coat has failed and corrosion has begun shouldbe spot cleaned, primed, and top coated promptly to pre-vent further corrosion (see Fig. 3.2). Dirt, sand, trash,coverstone, etc., tend to collect beneath open deck ex-pansion joints and deck drainage appurtenances, onlower flanges of outside girders, and on lower chord andfloor beam connections on truss spans (see Fig. 2.12 and3.3).5 This debris becomes saturated at times, causingcorrosion and eventual loss of section of the bridgemembers. The corrosion is accelerated if the moisturecontains deicing chemicals. Therefore, these areas shouldbe properly cleaned and maintained on a regular basis.15

Any cracks observed in steel members should be re-ported immediately. Cracks could be the result of metalfatigue and could spread rapidly. Cracks in main mem-bers may justify closing the bridge to traffic untilretrofitting can be accomplished.

Fig. 3.2-Steel corrosion

Fig. 3.3-Debris lodged in truss connection

3.4-Bearings.Attention should be given to all bearings (see Fig.

3.4).3,5,11 1Particular maintenance attention should be givento steel expansion bearings under open deck expansion.joints (see Fig. 3.5). Sand, dirt, coverstone, trash, etc.,often accumulate around the bearings and at timesbecome moisture saturated causing corrosion and sub-sequent “freezing” of the bearing (see Fig. 3.6). Thecorrosion process is accelerated if the moisture containsdeicing chemicals. With the bearing “frozen,” the bridgeis restrained from expanding or contracting with tem-perature changes, thus transmitting compressive or ten-sile stresses to the girder and substructure cap causingone or the other, or both, to be damaged. All bearingsshould be properly maintained so as to function asdesigned.

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Fig. 3.4-Failed bearing ig. 3.5-Bearing under open deck joint

CHAPTER 4-SUBSTRUCTURE

4.1-GeneralSubstructures transmit loads from the superstructure

down to the soil and include two types: abutments andintermediate support3,4 Intermediate supports canusually be further classified as bents or piers. Elementsof substructure units include the cap, above-groundportion, and below-ground portion, which includes thefootings.

4.2-Routine maintenanceDirt and debris often accumulate on the caps under

open expansion joints and can become saturated withmoisture and deicing chemicals (see Fig. 3.6).11 Ifpermitted to remain for extended periods of time, theywill penetrate the concrete causing corrosion of thereinforcing steel with subsequent spalls and deteriorationof the concrete (see Fig. 4.1). These areas should becleaned periodically and, if necessary, the concrete sealedto protect against the effects of deicing chemicals pen-etration. A modified polyurethane elastomeric coating issometimes used as a sealant for concrete pier caps. Mul-tiple applications of a 50-50 mixture of boiled linseed oiland mineral spirits or kerosene have also been used suc-cessfully.1,3

Fig. 3.6-Debris on substructure underopen deck joint

Fig. 4. I-Pier cap deterioration

CHAPTER 5-ROADWAY APPROACHES

5.1-Pavement expansion jointAt the time the concrete approach pavement is built,

an expansion joint is usually provided near the end of thebridge.2,4 The purpose of this joint is to prevent a buildupof pressure on the backwall of the abutment or the endof the deck caused by the expansion of the pavement.16

It is necessary to keep the pavement from en-croaching on the abutments and bridge. When the pave-ment expansion closes these joints, it may be necessary tosaw and/or break out about a 3 in. wide full-depth jointand fill it with an appropriate compressible material. Onematerial which has proven economical and satisfactory is

a bituminous fiier composed of approximately 1 part byvolume of rapid-cure, cut-back liquid asphalt and 2 partsby volume of air-dried sawdust. The proportion may beadjusted to vary the density, but the mixture should besuch that free asphalt will not “bleed” out when themixture is compacted.

If the pavement expansion continues, it may benecessary to repeat this process.

5.2-Leveling approachesLevel approaches prevent excessive live load impact

to bridge decks.5,166This impact can produce unnecessarystress and damage to the deck and supporting members.Slab jacking or other remedial treatment may be used tolevel a concrete approach.

5.3-Approach roadway shouldersApproach roadway shoulders have a tendency to build

up due to the accumulation of roadway debris. This con-dition can restrict drainage at the bridge ends and cancause ponding of water. When this condition exists, itmay be necessary to remove the approach safety guard-rail and shave the shoulders to provide proper drainage.

MAINTENANCE OF CONCRETE BRIDGES 345.1R-11

CHAPTER 6-BRIDGE SLOPES

5.4-Approach roadway surfacingWhere the bridge is wider than the approach road-

way, a drainage problem sometimes develops. The areabetween the roadway and the wingwalls becomes low,permitting water to stand. This allows weeds to grow,hiding the railing and curbs. In addition, this can causehydrostatic pressure against the backwall and wings, andmay permit water containing deicing chemicals to standand soak into the concrete.

To alleviate this condition, concrete or asphalticmaterial may be placed in this area, taking care to insureproper drainage. This should provide better deck drain-age and sight distance eliminating future handwork.

5.5-Approach roadway guttersGutters at bridge ends help to prevent erosion of side

slopes and runoff from getting under the approach pave-ment and washing out the fill behind and/or under theabutments (see Fig. 5.1, 5.2, and 5.3).

The gutters should be low enough at the shoulders sothat the roadway drainage is permitted to run off andlong enough to allow the roadway drainage to be dis-charged away from the bridge. In many instances, slides(as depicted in Fig. 5.4) are contributed to by suchimproper drainage.

Gutters should be of sufficient size to carry theroadway drainage without overflowing. If constructed ofasphaltic materials, they should be resealed periodically.

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Fig. 5.1-Erosion at bridge end ig. 5.2-Erosion at bridge end F ig. 5.3-Erosion under bridge

5.6-Joints at bridge endsThe joints between the perimeter of the approach

roadway and the bridge end and wingwalls should bekept sealed (see Fig. 5.2). This will prevent water fromgetting under the approach pavement which, in turn, mayprevent “pumping” of the approach pavement that couldresult in broken and rough pavement and/or shoving ofthe abutment. It will also prevent erosion of the fill andpossible deterioration of the concrete abutment. Prior toresealing, it is usually necessary to clean the joint beforefilling it with a compressible material.

6.1-Concrete slope protectionWeeds growing in the joints of the concrete slope

protection may cause spreading of the joint and even-tually permit water to enter and undermine the slopeprotection.2 Weeds also retain debris and dirt on theslope and prevent effective sealing of the joint (see Fig.6.1).

The joint at the top of the slope protection is oftenopen because of a downward slippage of the slope pro-tection. This should be inspected frequently and resealedperiodically.

All open joints should be filled with a compressiblematerial such as asphalt or a mixture of asphalt and saw-dust.4

6.2-Erosion under curb outletsBank erosion, much like that depicted in Fig. 5.3, is

sometimes caused by deck drainage through curb outletsand downspouts. One remedy is to block the curb outletsin this area, but since good bridge deck drainage is mostimportant, the erosion should be prevented by othermeans.5 Eroded areas may be backfilled with rock,broken pavement, etc. In some instances it might beadvantageous to build gutters to take care of thedrainage from curb outlets.

CHAPTER 7-STREAM CHANNELS

7.1-DriftDrift allowed to accumulate and become partially

buried in silt can cause several problems, includingshifting the channel alignment and promotion of scour-ing.2,4 Drift piled up ga ainst piers or bents can producean excessive horizontal force on the substructure ele-

345.1R-12 ACI COMMITTEE REPORT

Fig. 5.4-Substructure movement caused by slide

.

. _

Fig. 6.1-Vegetation growing in slope protection

ments, especially in times of high water.5,17 This force has,in some instances, caused timber piling to split or break(see Fig. 7.1).

Drift also constitutes a fire hazard and should bepromptly and completely removed from the channel.

Fig. 7.1-Timber pile broken by drift

7.2-Brush and vegetationKeeping brush and high vegetation cut will provide

easier access to the underside of the bridge.Vines growing on substructure elements may cause

deterioration where the tentacles grow into cracks, splits,and joints. They may also hold moisture which can pene-trate and cause corrosion and deterioration.

Sprouts should be cut close to the ground and, forreasons of safety, not cut on an angle producing a point.

CHAPTER 8-REFERENCES

8.l-Recommended referencesThe documents of the various standards-producing

organizations referred to in this document are listedbelow with their serial designation:

American Concrete Institute201.2R Guide to Durable Concrete504R Guide to Joint Sealants for Concrete

Structures

MAINTENANCE OF CONCRETE BRIDGES 345.1R-13

546.1R Guide for Repair of Concrete BridgeSuperstructures

The above publications may be obtained from thefollowing organization:

American Concrete InstituteP.O. Box 19150Detroit, MI 48219-0150

8.2-Cited references1. Guide for Maintenance Management, American

Association of State Highway and TransportationOfficials, Washington, D.C., 1980, 110 pp.

2. Manual for Maintenance Inspection of Bridges,American Association of State Highway and Trans-portation Officials, Washington, D.C., 1978, pp. 3-16.

3. Manual for Bridge Maintenance, American Asso-ciation of State Highway and Transportation Officials,Washington, D.C., 1976, 251 pp.

4. Bridge Inspectors Training Manual, Federal HighwayAdministration, Washington, D.C., 1971, 234 pp.

5. “Minor Maintenance of Highway Bridges,” CountyHighway Series Bulletin No. 7, Purdue UniversityEngineering Experimental Station, Lafayette, 1964,44 pp.

6. Snyder, M. Jack, “Protective Coatings to PreventDeterioration of Concrete by Deicing Chemicals,”NCHRP Report No. 16, Highway Research Board, Wash-ington, D.C., 1965, 21 pp.

7. “Concrete Bridge Deck Durability,” NCHRPSynthesis No. 4, Highway Research Board, Washington,D.C., 1970, 28 pp.

8. “Rapid-Setting Materials for Patching of Concrete,”NCHRP Synthesis No. 45, Transportation ResearchBoard, Washington, D.C., 1977, 13 pp.

9. “Durability of Concrete Bridge Decks,” NCHRPSynthesis No. 57, Transportation Research Board, Wash-ington D.C., 1979, pp. l-20; 25-48.

10. “Bridge Drainage Systems,” NCHRP Synthesis No.67, Transportation Research Board, Washington, D.C.,1979, pp. 2-4; 10; 29-35.

11. “Bridge Bearings,”NCHRP Synthesis No. 41,Transportation Research Board, Washington, D.C., 1977,pp. 43-48.

12. “Evaluation of Methods of Replacement of Deter-iorated Concrete in Structures,” NCHRP Synthesis No. 1,Highway Research Board, Washington, D.C., 1963, 56pp.

13. “Bridge Deck Joint Sealing Systems,” NCHRPReport No. 204, Transportation Research Board, Wash-ington, D.C., 1979, 46 pp.

14. “Bridges on Secondary Highways and Local Roads--Rehabilitation and Replacement,” NCHRP Report No.222, Transportation Research Board, Washington, D.C.,1980, 132 pp.

15. “County Bridge Painting,” County Highway SeriesBulletin No. 8, Purdue University Engineering Exper-iment Station, Lafayette, 1966, pp. 3-29.

16. “Bridge Approach Design and ConstructionPractices,” NCHRP Synthesis No. 2, Highway ResearchBoard, Washington, D.C., 1969, pp. 1-21.

17. “Scour at Bridge Waterways,” NCHRP SynthesisNo. 5, Highway Research Board, Washington, D.C., 1970,pp. 3-7; 10-11; 20-22.