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.
345.1R-1
ACI COMMlTTEE REPORT
345.1R-2
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
___^,
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
.-
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.
345.1 R-3
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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ACI COMMITTEE REPORT
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
MAINTENANCE OF CONCRETE BRIDGES
345.1R-5
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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ACI COMMITTEE REPORT
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
MAINTENANCE OF CONCRETE BRIDGES
345.1R-7
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
.
Fig. 2.17-Cracked deck girder end
“‘.
Fig. 2.20-Debris in deck drain
345.1R-8
ACI COMMITTEE REPORT
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
MAINTENANCE OF CONCRETE BRIDGES
345.1R-9
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.
345.1R-10
ACI COMMITTEE REPORT
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
345.1R-11
MAINTENANCE OF CONCRETE BRIDGES
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
ACI COMMITTEE REPORT
345.1R-12
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
.
.
_
Fig. 6.1-Vegetation growing in slope protection
Fig. 7.1-Timber pile broken by drift
MAINTENANCE OF CONCRETE BRIDGES
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.
345.1R-13
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.