ACI 345.1R-92 (Reapproved 1997)

Routine Maintenance of Concrete Bridges Reported by ACI Committee 345 Robert V. Gevecker Secretary

Ralph L. Duncan Chairman

Peter Meza Howard H. Newlon, Jr. Orrin Riley William Rohde* Arthur P. Seyler Donald W. Vannoy

Donald W. Alden Ralph K. Banks Claudius A. Carnegie Kenneth C. Clear John J. Corigliano Robert N. Dentz Paul Klieger * Deceased

Committee members voting on 1992 revisions:

John L Carrato Chairman Paul Klieger Surinder K. Lakhanpal Paul F. McHale Harry L Patterson Orrin Riley William F. Schoen Virendra K. Varma

John H. Allen Paul D. Carter Ralph L Duncan Robert V. Gevecker Robert J. Gulyas Allan C. Harwood Mark R. Heim Various potential sources of distress and the possible areas affected in the roadway, superstructure, substructure, approaches, slopes, and channel of a bridge are described Guidance for avoiding or correcting such troubles is also provided in the form of a day-to-day maintenance and preventive maintenance guide. The report is directed to the local maintenance supervisor who has the responsibility for routine bridge maintenance. Keywords: Bridge decks; bridges (structures): cleaning concrete pavements; control joints; drains; highway bridges; maintenance; slope protection; substructures; superstructures.

CONTENTS

Chapter l-Introduction, pg. 345.1R-2 1.1-General 1.2-Preventive maintenance 1.3-Scope ACI Committee Reports, Guides, Standard Practices, and Commentaries are intended for guidance in designing, planning, executing, or inspecting construction and in preparing specifications. Reference to these documents shall not be made in the Project Documents. If items found in these documents are desired to be part of the Project Documents they should be phrased in mandatory language and incorporated into the Project Documents.

Chapter 2-Roadways, pg. 345.lR-2 2.1-General 2.2-Cleaning and flushing 2.3-Deck cracks 2.4-Deck treatments 2.5-Asphaltic concrete overlays 2.6-Expansion joints and devices 2.7-Deck drains 2.8-Snow removal Chapter 3-Superstructures, pg. 345.1R-8 3.l-General 3.2-Concrete superstructures ACI 345.1R-92 supersedes ACI 345.1R-83 effective February 1, 1992. Minor revisions have been made to the report in 1992. The reference chapter has been reformatted and the year designation of the recommended references of the standard producing organizations has been removed so that the current editions become 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 any electronic or mechanical device, printed or written or oral, or recording for sound or 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 superstructures 3.4-Bearings

CHAPTER 1-INTRODUCTION

Chapter 4-Substructures, pg. 345.lR-9 4.1-General 4.2-Routine maintenance Chapter 5-Roadway approaches, pg. 345.1R-10 5.1-Pavement expansion joint 5.2-Leveling approaches 5.3-Approach roadway shoulders 5.4-Approach roadway surfacing 5.5-Approach roadway gutters 5.6-Joints at bridge ends Chapter 6-Bridge slopes, pg. 345.1R-11 6.1-Concrete slope protection 6.2-Erosion under curb outlets Chapter 7-Stream channels, pg. 345.1R-12 7.1-Drift 7.2-Brush and vegetation Chapter 8-References, pg. 345.1R-12 8.l-Recommended references 8.2-Cited references

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

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

ture. The elements of the structure, from foundation to parapets and railings, must interact with each other in a unique, efficient way. The special features designed to enhance safety and to provide a pleasing overall appearance are also important in the service the bridge provides. The malfunction of one element can affect the overall operational efficiency of the structure. The movement of a pier can cause collapse of an entire span; a damaged bearing seat might cause deck failure or collapse of an entire span; a slick deck invites collision of vehicles with each other or with the bridge parapet or railing. Experience in highway operation has shown that continuous and systematic maintenance of a bridge will extend its service life and reduce its operating expense.’ Nevertheless, maintenance of bridges and their approaches is often the most neglected phase of highway operation. l.2-Preventive maintenance

As soon as a bridge is constructed and put into service, its deterioration begins. The changes that develop

Fig. 2.2-Severe deterioration in the top of the deck

Fig. 2.3-Water saturated concrete

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

Fig. 2.5-Ponding of water on the deck caused by snow

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

MAINTENANCE OF CONCRETE BRIDGES

Fig. 2.7-Water penetrating concrete deck

are gradual and usually slow, and there is a tendency to give them little attention. The sudden catastrophic event is the one that demands immediate action. Some of these developments can be avoided if good systematic, preventive maintenance is practiced. Tried and proven practices of day-to-day maintenance can keep the bridge operating efficiently. Periodic inspection of all components of the structure should be made in a careful and systematic way to locate areas that need attention before they become major 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, it should be promptly reported. 1.3-Scope This report lists and discusses various potential problems and the areas that might be affected in a bridge. It provides guidance for avoiding and/or correcting such problems. It is intended as a day-to-day maintenance guide for the supervisor who has responsibility for routine bridge maintenance. It is not intended as a manual of repair, rehabilitation, reconstruction, or bridge inspection. This guide should, however, be of interest and use to all engineers and technicians in those fields. Many detailed methods of repairing bridges are found in References 3, 8, 12, 14, and ACI 546.1R. Guidelines for conducting bridge inspections are found in References 2, 3, 4, 5, and 9. Useful information on the subject of bridge maintenance may be found in these and other references listed in Chapter 8 including ACI 504R and ACI 201.2R. This report is presented under the following chapter headings: Roadways, Superstructures, Substructures, Roadway Approaches, Bridge Slopes, and Stream Channels.

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Fig. 2.8-Scaling deck

CHAPTER 2-ROADWAYS 2.1-General The bridge roadway includes the deck, with or without separately applied wearing surfaces, joints, railings, parapets, median barriers, curbs, sidewalks, and deck drainage systems.3,4 Loose and deteriorated concrete and water-saturated areas commonly occur on the bridge deck, both top and bottom. Examples of severe deterioration are shown in

Fig. 2.9-Spalling deck

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Fig. 2.10-Severely deteriorated paint system Fig. 2.1, 2.2, and 2.3. Damage of this type is usually the result of freezing and thawing action on the concrete, corrosion of the reinforcing steel, or a combination of the two. Water containing chlorides penetrates the concrete and initiates these actions. Water ponded on the deck accelerates them.7 Exposed deterioration can be located by visual inspection. Nonvisual damage, such as delaminated concrete, can be detected by the hollow sound made by a chain drag or sounding with a hammer.9 2.2-Cleaning and flushing 2.2.1 Periodic cleaning and flushing of concrete decks, drains, expansion joints, lower chords, bent caps, and other elements should be performed.5,10 2.2.2 All drainage devices, such as curb outlets, pipe drains, floor drains, downspouts, etc., should be adequately cleaned to prevent pending of water on the deck (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 causing deterioration, especially in the areas of cracks and joints (see Fig. 2.7). 2.2.3 It is usually necessary to use a combination of shovels, brooms, compressed air, trash pumps, mobile cleaners, or water under pressure to remove the saltladen dirt and debris which cause or accelerate the following: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).

Fig. 2.11-Bentcap damage caused by "frozen" bearing and sudden drop in temperature c) Deterioration of paint systems and corrosion of the supporting members (see Fig. 2.10). d) Corrosion and “freezing” of the expansion bearings. A sudden drop in temperature causes the structure to contract rapidly. With the bearings “frozen,” excessive tensile stresses are transmitted to the concrete under the bearing pad, often causing it to crack along a line through the anchor bolts (see Fig. 2.11). 2.2.4 One of the more critical and most commonly overlooked problem areas is the lower chord and floor beam flanges and connections on truss spans. Here, accumulations of dirt, trash, and debris can contribute to considerable corrosion and deterioration of truss members (see Fig. 2.12). Periodic cleaning is necessary to preserve the paint system and to avoid any loss of section in the steel members at these points.5 2.3-Deck cracks 2.3.1 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 chemicals into the deck cracks, can create several problems.7,9 a) The moisture and chemicals cause the reinforcing steel to corrode. The corrosion products swell or expand causing the concrete to spall over the reinforcing steel (see Fig. 2.14). b) The water remains trapped in the crack and freezing temperatures or traffic action will contribute to spall development. 2.3.3 Sealing these cracks with asphalt or other materials suitable for the purpose can prevent a considerable amount of moisture from entering the cracks

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Fig. 2.12-Debris collected on lower chord

Fig. 2.13-Deck cracks

and thus slow deterioration of the concrete deck (see Fig. 2.15).3 2.3.4 Deicing salts in solution can also enter uncracked concrete by permeating the surface, causing corrosion of the embedded steel and subsequent cracking.

For a short time after application, daily removal of excess coverstone from the deck is important to reduce windshield damage and avoid blocking drains. In addition, the excess coverstone should be removed from the substructure caps and lower chords of truss spans. This excess coverstone may be reused for scalping and sealing areas around timber abutments and abutment wings or for sealing gutters at the bridge ends.

2.4-Deck treatments 2.4.1 Concrete bridge decks, in many cases, are

treated for protection against the effects of moisture and deicing chemicals. Prior to the use of any deck treatment, the effect the treatment has on the skid resistance characteristics of the surface should be investigated. Commonly, new and existing decks subjected to frequent freezing and thawing cycling, high moisture, and/or frequent exposure to seawater are treated with a 50-50 mixture of boiled linseed oil and kerosene, mineral spirits, or a similar compound.3,6,7,9 Periodic follow-up applications are usually required.1 2.4.2 A penetration asphalt surface treatment, or equivalent sealer, may be considered for application over significantly cracked or extensively patched decks.3,9 The traffic volume, grade, and bridge alignment should be considered prior to sealing as these factors greatly influence the successful performance of the seal. When sealing a bridge deck, the entire deck area should be covered, including the curb outlets. The area inside the outlet, however, should not be included when the coverstone is broadcast on the deck. The coverstone in these areas cannot be rolled, and could restrict the deck drainage due to material buildup. Care should be exercised to keep the deck expansion devices free of sealant material which might interfere with their proper functioning and movement. Any material which may enter an expansion device should be removed promptly and completely.

2.5-Asphaltic concrete overlays 2.5.1 Asphaltic concrete overlays are used on bridge

Fig. 2.14-Deck spalls

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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 and bonding agent before the asphaltic overlay is placed. Care should be taken to assure that the overlay is thoroughly compacted. 2.6-Expansion joints and devices 2.6.1 Deck joints provide for expansion and con-

Fig. 2.1 5-"Sealed" cracks decks to provide a smooth riding surface and help reduce damaging impact to the deck. They are also commonly used as a protective wearing surface for penetration asphalt, membrane waterproofing systems, or other deck sealers. Prior to the use of any overlay or increasing the thickness of an existing overlay, the ability of the structure to carry the added load should be investigated. As a rule, however, asphaltic concrete overlays are relatively porous and, by themselves, do not provide an effective seal.7,12 2This porosity entraps salt-laden moisture which, in the absence of an effective deck sealer, can promote deck deterioration. As a precautionary measure a multiple-course penetration asphalt surface treatment, membrane, or other deck sealer should always be applied prior to an asphaltic concrete overlay. 2.5.2 When placing asphaltic concrete overlays, end dams should be provided at expansion joints to protect the overlay next to the joint and to keep overlay material out of the joint. Existing asphaltic overlays on concrete bridge decks should be inspected periodically for cracking and debonding from the concrete.3 A hammer or rod may be used to locate unbonded areas in the overlay. These areas are more commonly found along curbs, expansion joints, and at locations where the overlay has cracked. Once located, the overlay in these loose areas should be removed and replaced. 2.5.3 Attempts should also be made to determine the condition of the concrete beneath the overlay.9,12 If the concrete deck is deteriorated, all unsound concrete should be removed and replaced prior to replacing the asphaltic overlay (see Fig. 2.16). Care should be taken to finish the concrete patch flush with the existing deck. Dormant cracks in the con-crete should be filled and active cracks should be sealed with a crack-sealing

traction of the bridge.33The joints may sometimes be filled with a compressible material to keep drainage and incompressibles out of the joint. If these joints should become filled with incompresibles (dirt, sand, coverstone, debris, etc.), a concrete deck and/or the girder ends may crack or crush when expanding (see Fig. 2.17). In many instances, this causes undue pressure on the superstructure bearings, resulting in cracking and spalling of a concrete substructure cap (see Fig. 2.18). On some bridges, especially concrete spans built on a skew, this condition may cause transverse movement of the deck with resultant curb offsets obstructing traffic (see Fig. 2.19). Debris filled joints may also collect moisture and deicing chemicals which can deteriorate the adjacent deck. 2.6.2 Expansion joints - Filled expansion joints should be periodically cleaned of all incompressible materials. Before replacing joint filler, it should be determined whether there is need to do so since changed conditions may dictate otherwise. Possible replacement joint materials include asphaltimpregnated felt or polyurethane foam topped with poured-in-place rubber asphalt, polyvinyl chloride, polysulfide, neoprene, butyl rubber, or polyurethane?’ 2.6.3 Steel expansion devices - To assure free movement, steel expansion devices should be kept clean and free of incompressible materials.3 In some cases, flat plate expansion devices close due to the abutments moving. This movement results in considerable pressure on both the abutment backwall and the expansion device anchorage in the ends of the deck, and could lead to failure in either of these areas. To partially alleviate this condition, the flat plate may be trimmed, thus relieving pressure. Steps may have to be taken to relieve the pressure which caused the abutment movement. 2.6.4 Elastomeric expansion devices - In recent years considerable attention has been given to the development of sealed and watertight joint devices that will expand and contract with bridge movements.13 An elastomeric device, usually consisting of neoprene and metal, is one such type being used on many newer bridges. These devices are vulnerable to snowplow damage, particularly if they are not designed and/or installed properly. The anchorage of these devices should be periodically checked to ensure no sections have worked loose and become traffic hazards. 2.7-Deck drains

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Fig. 2.18-Concrete pulled off of bent cap

Fig. 2.16-Unsound concrete removed

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

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Fig. 2.17-Cracked deck girder end

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Fig. 2.20-Debris in deck drain

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2.7.2 Drains discharging directly beneath the deck can usually be cleared with common equipment. However, more elaborate drainage systems may require special tools and equipment.10 2.7.3 Drainage discharging onto supporting members should be directed away from these members (see Fig. 2.21). 2.7.4 Decks with no drains, or those suspected of having an insufficient number, should be observed shortly after a rain for areas of ponding water. Such areas should then be marked where additional drains are warranted. Round pipe drains are normally installed where the deepest water stands.5 Care must be exercised in locating these drains to avoid drilling holes through concrete girders or steel stringer flanges, or allowing the discharge of water onto roadways underneath (see Fig. 2.22 and 2.23). The pipe should be recessed into the deck and should be long enough to direct water away from structural members.10 After the pipe is installed, a mortar should be used to grout around the opening to fill any existing voids. Damage to the top and bottom of the deck resulting from the drilling operation should also be repaired. 2.8-Snow removal

Fig. 2.21-Deck drainage directed away from pier cap 2.7.1 Bridge deck drainage systems should be kept clear of debris and functioning to avoid ponding water which can lead to vehicle hydroplaning or skidding on ice. Continued ponding also promotes rapid concrete deck deterioration. Stoppages often occur when items such as bottles, cans, and other rubbish accumulate at, or lodge within drains (see Fig. 2.20).3,10

Fig. 2.22-Deck drainage directed away from the roadway underneath the bridge

Care should be exercised when plowing snow on bridges. Some bridges have elastomeric expansion joint devices which are easily damaged by snowplows, while others are skewed to roughly the same degree as the snowplow, which causes a jolt to the driver and damaging impact to the truck and the bridge if the snow plow drops into a joint.3 Care should be exercised to prevent plow damage to the curbs, parapets, railings, and joint sealant systems. CHAPTER 3-SUPERSTRUCTURES 3.1-General The superstructure component includes main mem-

bers, the floor system, secondary members, and bearing

Fig. 2.23-Deck drainage directed away from stringer

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elements.3,4 Main members are those whose failure would result in collapse of the structure, including concrete, steel or timber girders, truss chords, diagonals, and verticals. Floor systems include members which transmit loads from the roadway to the main members. Failure of the floor system members would usually have only local effects. Secondary members add stiffness to the main members. Bearings are the mechanical devices which transfer the loads from main members to the substructure and also allow for longitudinal and/or rotational movements of the main members. 3.2-Concrete superstructures

Fig. 3.1-Cracked concrete girder

In concrete superstructures, attention should be given to any serious cracks or spalls (see Fig. 3.1). These defects may be indications of structural distress and could allow water and deicers to penetrate to reinforcing steel and cause corrosion. Such areas should be sealed by the use of an appropriate grout or patching compound.3 3.3-Steel superstructures

Fig. 3.2-Steel corrosion

For most steel superstructures, other than those of weathering steel, it is essential that the integrity of the protective coating system be kept intact.3 Areas where the prime coat has failed and corrosion has begun should be spot cleaned, primed, and top coated promptly to prevent further corrosion (see Fig. 3.2). Dirt, sand, trash, coverstone, etc., tend to collect beneath open deck expansion joints and deck drainage appurtenances, on lower flanges of outside girders, and on lower chord and floor beam connections on truss spans (see Fig. 2.12 and 3.3).5 This debris becomes saturated at times, causing corrosion and eventual loss of section of the bridge members. The corrosion is accelerated if the moisture contains deicing chemicals. Therefore, these areas should be properly cleaned and maintained on a regular basis.15 Any cracks observed in steel members should be reported immediately. Cracks could be the result of metal fatigue and could spread rapidly. Cracks in main members may justify closing the bridge to traffic until retrofitting can be accomplished. 3.4-Bearings.

Fig. 3.3-Debris lodged in truss connection

Attention should be given to all bearings (see Fig. 3.4).3,5,11 1Particular maintenance attention should be given to steel expansion bearings under open deck expansion. joints (see Fig. 3.5). Sand, dirt, coverstone, trash, etc., often accumulate around the bearings and at times become moisture saturated causing corrosion and subsequent “freezing” of the bearing (see Fig. 3.6). The corrosion process is accelerated if the moisture contains deicing chemicals. With the bearing “frozen,” the bridge is restrained from expanding or contracting with temperature changes, thus transmitting compressive or tensile stresses to the girder and substructure cap causing one or the other, or both, to be damaged. All bearings should be properly maintained so as to function as designed.

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Fig. 3.4-Failed bearing

Fig. 3.5-Bearing under open deck joint

CHAPTER 4-SUBSTRUCTURE 4.1-General

Substructures transmit loads from the superstructure down to the soil and include two types: abutments and intermediate support3,4 Intermediate supports can usually be further classified as bents or piers. Elements of substructure units include the cap, above-ground portion, and below-ground portion, which includes the footings.

Fig. 3.6-Debris on substructure under open deck joint

a bituminous fiier composed of approximately 1 part by volume of rapid-cure, cut-back liquid asphalt and 2 parts by volume of air-dried sawdust. The proportion may be adjusted to vary the density, but the mixture should be such that free asphalt will not “bleed” out when the mixture is compacted. If the pavement expansion continues, it may be necessary to repeat this process.

5.2-Leveling approaches 4.2-Routine maintenance

Dirt and debris often accumulate on the caps under open expansion joints and can become saturated with moisture and deicing chemicals (see Fig. 3.6).11 If permitted to remain for extended periods of time, they will penetrate the concrete causing corrosion of the reinforcing steel with subsequent spalls and deterioration of the concrete (see Fig. 4.1). These areas should be cleaned periodically and, if necessary, the concrete sealed to protect against the effects of deicing chemicals penetration. A modified polyurethane elastomeric coating is sometimes used as a sealant for concrete pier caps. Multiple applications of a 50-50 mixture of boiled linseed oil and mineral spirits or kerosene have also been used successfully.1,3

Level approaches prevent excessive live load impact to bridge decks.5,166This impact can produce unnecessary stress and damage to the deck and supporting members. Slab jacking or other remedial treatment may be used to level a concrete approach.

5.3-Approach roadway shoulders

Approach roadway shoulders have a tendency to build up due to the accumulation of roadway debris. This condition can restrict drainage at the bridge ends and can cause ponding of water. When this condition exists, it may be necessary to remove the approach safety guardrail and shave the shoulders to provide proper drainage.

CHAPTER 5-ROADWAY APPROACHES 5.1-Pavement expansion joint

At the time the concrete approach pavement is built, an expansion joint is usually provided near the end of the bridge. 2,4 The purpose of this joint is to prevent a buildup of pressure on the backwall of the abutment or the end of the deck caused by the expansion of the pavement.16 It is necessary to keep the pavement from encroaching on the abutments and bridge. When the pavement expansion closes these joints, it may be necessary to saw and/or break out about a 3 in. wide full-depth joint and fill it with an appropriate compressible material. One material which has proven economical and satisfactory is

Fig. 4. I-Pier cap deterioration

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5.4-Approach roadway surfacing

CHAPTER 6-BRIDGE SLOPES

Where the bridge is wider than the approach roadway, a drainage problem sometimes develops. The area between 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 cause hydrostatic pressure against the backwall and wings, and may permit water containing deicing chemicals to stand and soak into the concrete. To alleviate this condition, concrete or asphaltic material may be placed in this area, taking care to insure proper drainage. This should provide better deck drainage and sight distance eliminating future handwork. 5.5-Approach roadway gutters

Gutters at bridge ends help to prevent erosion of side slopes and runoff from getting under the approach pavement and washing out the fill behind and/or under the abutments (see Fig. 5.1, 5.2, and 5.3). The gutters should be low enough at the shoulders so that the roadway drainage is permitted to run off and long enough to allow the roadway drainage to be discharged away from the bridge. In many instances, slides (as depicted in Fig. 5.4) are contributed to by such improper drainage. Gutters should be of sufficient size to carry the roadway drainage without overflowing. If constructed of asphaltic materials, they should be resealed periodically.

6.1-Concrete slope protection

Weeds growing in the joints of the concrete slope protection may cause spreading of the joint and eventually permit water to enter and undermine the slope protection.2 Weeds also retain debris and dirt on the slope and prevent effective sealing of the joint (see Fig. 6.1). The joint at the top of the slope protection is often open because of a downward slippage of the slope protection. This should be inspected frequently and resealed periodically. All open joints should be filled with a compressible material such as asphalt or a mixture of asphalt and sawdust.4

6.2-Erosion under curb outlets

Bank erosion, much like that depicted in Fig. 5.3, is sometimes caused by deck drainage through curb outlets and downspouts. One remedy is to block the curb outlets in this area, but since good bridge deck drainage is most important, the erosion should be prevented by other means.5 Eroded areas may be backfilled with rock, broken pavement, etc. In some instances it might be advantageous to build gutters to take care of the drainage from curb outlets.

5.6-Joints at bridge ends

The joints between the perimeter of the approach roadway and the bridge end and wingwalls should be kept sealed (see Fig. 5.2). This will prevent water from getting under the approach pavement which, in turn, may prevent “pumping” of the approach pavement that could result in broken and rough pavement and/or shoving of the abutment. It will also prevent erosion of the fill and possible deterioration of the concrete abutment. Prior to resealing, it is usually necessary to clean the joint before filling it with a compressible material.

Fig. 5.1-Erosion at bridge end

CHAPTER 7-STREAM CHANNELS 7.1-Drift

Drift allowed to accumulate and become partially buried in silt can cause several problems, including shifting the channel alignment and promotion of scouring.2,4 Drift piled up ag ainst piers or bents can produce an excessive horizontal force on the substructure ele-

Fig. 5.2-Erosion at bridge end

Fig. 5.3-Erosion under bridge

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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 be promptly and completely removed from the channel. 7.2-Brush and vegetation

Keeping 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 penetrate and cause corrosion and deterioration. Sprouts should be cut close to the ground and, for reasons of safety, not cut on an angle producing a point. CHAPTER 8-REFERENCES

8.l-Recommended references The documents of the various standards-producing organizations referred to in this document are listed below with their serial designation: American Concrete Institute Guide to Durable Concrete 201.2R

504R Fig. 5.4-Substructure movement caused by slide

Guide to Joint Sealants for Concrete Structures

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Fig. 6.1-Vegetation growing in slope protection

Fig. 7.1-Timber pile broken by drift

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546.1R

Guide for Repair of Concrete Bridge Superstructures

The above publications may be obtained from the following organization: American Concrete Institute P.O. Box 19150 Detroit, MI 48219-0150 8.2-Cited references 1. Guide for Maintenance Management, American

Association of State Highway and Transportation Officials, Washington, D.C., 1980, 110 pp. 2. Manual for Maintenance Inspection of Bridges, American Association of State Highway and Transportation Officials, Washington, D.C., 1978, pp. 3-16. 3. Manual for Bridge Maintenance, American Association of State Highway and Transportation Officials, Washington, D.C., 1976, 251 pp. 4. Bridge Inspectors Training Manual, Federal Highway Administration, Washington, D.C., 1971, 234 pp. 5. “Minor Maintenance of Highway Bridges,” County Highway Series Bulletin No. 7, Purdue University Engineering Experimental Station, Lafayette, 1964,44 pp. 6. Snyder, M. Jack, “Protective Coatings to Prevent Deterioration of Concrete by Deicing Chemicals,” NCHRP Report No. 16, Highway Research Board, Washington, D.C., 1965, 21 pp. 7. “Concrete Bridge Deck Durability,” NCHRP Synthesis No. 4, Highway Research Board, Washington, D.C., 1970, 28 pp.

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8. “Rapid-Setting Materials for Patching of Concrete,” NCHRP Synthesis No. 45, Transportation Research Board, Washington, D.C., 1977, 13 pp. 9. “Durability of Concrete Bridge Decks,” NCHRP Synthesis No. 57, Transportation Research Board, Washington 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 Deteriorated Concrete in Structures,” NCHRP Synthesis No. 1, Highway Research Board, Washington, D.C., 1963, 56 pp. 13. “Bridge Deck Joint Sealing Systems,” NCHRP Report 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 Series Bulletin No. 8, Purdue University Engineering Experiment Station, Lafayette, 1966, pp. 3-29. 16. “Bridge Approach Design and Construction Practices,” NCHRP Synthesis No. 2, Highway Research Board, Washington, D.C., 1969, pp. 1-21. 17. “Scour at Bridge Waterways,” NCHRP Synthesis No. 5, Highway Research Board, Washington, D.C., 1970, pp. 3-7; 10-11; 20-22.