546.1 R-80 Guide for Repair of Concrete Bridge … 546.1R-80, Guide... · ACI 546.1 R-80...

ACI 546.1 R-80(Reapproved 1988)

(Reapproved 1997)

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Guide for Repair ofConcrete Bridge Superstructures

Keywords: bridges (structures); concretes; concrete construction;epoxy resins; latex (plastic); plastics, polymers, and resins; re-pairs; shotcrete.

Reported by ACI Committee 546

Repair techniques for concrete bridge superstructuresare described. This includes pier caps, beams, decks,curbs, sidewalks, and rails. Special emphasis is placed ondecks. Recommendations for evaluation of damage, selec-tion of repair method, and surface preparation are given.Repair materials given primary consideration are con-ventional portland cement mortars and concretes, andthose using latex, epoxy resins, or methyl methacrylate.Only techniques that have been documented and used ex-tensively are included. Guide recommendations are thoseconsidered necessary for severe exposure conditions.

ContentsChapter 1 - Introduction,page 546.1R- 2

1.1 - General1.2 - Scope

Chapter 2 -Evaluation ofdamage and selection of re-pair method, page 546.1R-2

2.1 - General2.2 - Delaminations2.3 - Spalls2.4 - Scaling2.5 - Cracked or fractured sections of

concrete members2.6 - Rutting2.7 - Repair material characteristics

Chapter 3- Surface prepara-tion, page 546.1R-6

3.1 - Scope3.2 - Removal of deteriorated concrete3.3 - Reinforcing steel3.4 - Cleaning of area to be repaired3.5 - Cracks

mittee reports , guides, standard practices, design hand- commentaries are intended for guidance in planning, de-ecuting, and inspecting construction. This document isor the use of individuals who are competent to evalu-nificance and limitations of its content and recommen-d who will accept responsibility for the application ofl it contains. The American Concrete Institute disclaims responsibility for the stated principles. The Institute shalle for any loss or damage arising therefrom.e to this document shall not be made in contract docu-ems found in this document are desired by the Architect/ be a part of the contract documents, they shall be restatedry language for incorporation by the Architect/Engineer.

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Chapter 4- Portland cementconcrete, page 546.1R-7

4.1 - General4.2 - Materials and proportions4.3 - Batching and mixing4.4 - Full depth patches and formed re-

pairs4.5 - Partial depth patches4.6 - Overlays4.7 - Shotcrete4.8 - Curing

Chapter 5 -Latex modifiedportland cement mortar/con-crete, page 546.1R-11

5.1 - General5.2 - Materials and proportions5.3 - Batching and mixing5.4 - Patches5.5 - Overlays5.6 - Curing

Chapter 6 -Polymer con-crete, page 546.1R-13

6.1 - General6.2 - Epoxy concrete

6.2.1- Materials and proportions6.2.2 - Batching and mixing6.2.3 - Patches and overlays6.2.4 - Crack and fracture repair

with epoxy resins6.3 - Methyl methacrylate concrete

6.3.1 - Materials and proportions6.3.2 - Batching and mixing6.3.3 - Preplaced aggregate6.3.4 - Premixing and placing6.3.5 - Polymerization6.3.6 - Cleaning of tools and

equipment6.3.7 - Storage and handling of

materials6.3.8 - Disposal of excess mon-

omer

Chapter 7 - References, page546.1R-18Chapter 8 -Applicable speci-fications and standards, page546.1R-20

pyright 0 1997, American Concrete Institute.l rights reserved including rights of reproduction and use in any form or by anys, including the making of copies by any photo process, or by electronic oranical device printed, written, or oral, or recording for sound or visual reproduc-

or for use in any knowledge or retrieval system or device, unless permission in ng is obtained from the copyright proprietors.

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546.1R-2 ACI COMMITTEE REPORT

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Fig. 1 - Chain drag (courtesy State of CaliforniaDepartment of Transportation).

CHAPTER 1 - Introduction

1.1 - GeneralAlthough concrete bridges are generally durable

structures that provide good service over manyyears with minimum maintenance, damage requiringrepair does occur, and it occurs most commonly inthe deck. Chlorides from salts used to prevent ice orfrom sea spray contribute to, or are the source of,most deterioration. Damage may also be due to poordesign or construction, vehicle impact, or excessiveoverloading. Recommendations for the design andconstruction of bridge decks can be found in the re-port by ACI Committee 345.1

This Guide is not intended to answer the questionof whether a permanent or temporary repair shouldbe made. Limited funds may only allow the filling ofpot holes with an asphaltic material even though thismay accelerate deterioration. When the state ofdeterioration is too far advanced to reclaim the sur-face, a temporary riding surface such as an asphalticconcrete overlay may be expedient. This, too, mayaccelerate deterioration and it will conceal that dete-rioration so that safety evaluations become more dif-ficult. This Guide provides only information on rec-ommended techniques and materials for enduringrepairs.

Quite often it is necessary to keep bridges open totraffic while repairs are being made. The main-tenance of safe traffic conditions can be the mosttroublesome and costly item in the repair program.The daytime hours between peak traffic loads in ur-ban areas may not provide sufficient time to makerepairs with portland cement concrete. Special patchmaterials may be justified when their cost is com-pared to the expense of prolonged detouring or con-trolling traffic through the repair zone.

1.2 - ScopeThis Guide is intended for concrete super-

structures of bridges, including pier caps, beams, curbs, sidewalks, rails, and with special emphasis ondecks. The procedures can be used on other parts ofthe bridge or on other concrete structures.

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Repair materials included are conventional port-land cement mortars and concretes, and those utiliz-ing latex, epoxy resins, or methyl methacrylate.Each of these materials has been used extensively inbridge repair, and their performance is well docu-mented. Recommendations are those considered nec-essary for severe exposure conditions. Only proven,effective procedures are included. Procedures re-ported by Tuthill,2 Tremper,3 Kulberg,4 and Felt,5 onrestoration of deteriorated concrete provide the ba-sic approach for the methods presented.

Other products not included have been subject toevaluation by State highway or transportation de-partments. A large number (over 300) of these eval-uations are listed in the Patching Materials sectionof SPEL, Special Product Evaluation List.30

Many of these materials offer the advantage ofbeing rapid-setting materials with an acceleratedrate of strength gain compared to conventional port-land cement concrete mixes. Some of these materialsmay also have the property of very low shrinkage onsetting and curing, or may expand slightly on set-ting and curing. Some may be susceptible to deterio-ration from freeze-thaw cycles or to repeated cyclesof wetting and drying or to erosion from traffic.34 Inaddition, the cost of such repair materials may beseveral times that of conventional portland cementconcrete.33 Each material should be evaluated forany specific intended use by laboratory tests, perfor-mance records, and total repair cost effectiveness.

Repair costs are not directly considered in thisGuide. Costs will vary widely depending on type andextent of damage, its location, traffic conditions, andmaterials and methods of repair. Some costs are in-cluded in Reference 8. Material costs are presentedin Reference 33.

Chapter 2 - Evaluation of damage andselection of repair method

2.1 - GeneralAn evaluation of damage is essential in selecting a

repair method. To evaluate damage, it is necessaryto determine the extent, cause, and whether or notthe cause is still active. Guidance on surveys forthese determinations may be obtained from ACI 2017

and from ASTM C823.* The most common types ofdamage to bridge superstructures are defined in thischapter together with evaluation techniques. Witheach type of damage, applicable repair methods aresuggested. Some repair material characteristics areprovided. Selection of a repair material must bebased on an evaluation of the damage, repair mate-rial characteristics, and local conditions.

If detailed evaluation of a damaged structure re-veals that the original construction was of poor qual-ity concrete, a lasting repair can probably be

REPAIR OF BRIDGE SUPERSTRUCTURES 546.1R-3

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achieved with a high quality concrete or other patch-ing material. If a high quality concrete has deterio-rated, a lasting repair can only be achieved by mod-erating the exposure conditions and then repairingwith a high quality material. Examples of exposureconditions that can be changed are drainage condi-tions, exposure to chloride deicing agents, and lackof mechanical protection for rails or parapets. Localpatching is generally not advisable in extremely se-vere exposure conditions except for a temporary re-pair.

Repair materials must be compatible with the con-crete that is being repaired. They should respond inthe same way to changes in temperature and loads,and they should blend well in appearance.

The riding quality of the structure should be con-sidered in selection of the repair method. Poor rid-ing qualities may make an overlay of the entire deckdesirable rather than patching only deterioratedareas. Skid-resistant characteristics of the patch ma-terial or overlay must be evaluated to determine ifcurrent safety requirements can be met.

If chloride contamination, corrosion, and deteriora-tion of the concrete is extensive, patching may notbe practical. In these situations, it is advisable to re-place the entire slab or member. Removal of deterio-rated or chloride contaminated concrete, and surfacepreparation operations in small areas require a con-siderable amount of hand labor, whereas an entirebeam or deck can be removed by more economicalmethods.

A repair can be unsightly unless proper attentionis given to factors affecting its appearance. Whereappearance is important, particular care should betaken to ensure that the texture and color of the re-pair will blend with the surrounding concrete.

2.2 - DelaminationsDelaminations occur when layers of concrete sepa-

rate from bridge decks or beams at or near the levelof the top or outermost layer of reinforcing steel,generally parallel to the surface of the concretemember. Such areas give off a hollow sound whentapped with a rod or hammer. A chain drag, such asshown in Fig. 1, or other mechanical devices ,12 maybe used to determine the extent of delaminations.The surface should be inspected for cracks that mayhave permitted penetration by surface contaminants.

The major cause of delaminations is the expansionresulting from corrosion of reinforcing steel due tointrusion of chloride ions. This is discussed in the re-port of ACI Committee 201. 44 It occurs with eitherrepeated chloride deicer application or continued ex-posure to a marine environment.8 Inadequate coverover reinforcing steel will reduce the time to start ofcorrosion. Vehicular fires on bridges may also causedelaminations.

Depth of cover may be measured with either ahand-held 15 or a rolling pachometer.16 Determination

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of whether or not reinforcing steel corrosion is ac-tive may be made by measuring the electrical poten-tial using a copper-copper sulphate half-cell (ASTMC876), 13,17 as shown in Fig. 2, and by measuring thechloride ion content of the concrete (AASHTOT260) .14 When sufficient moisture and oxygen arepresent with a chloride ion content above 1.3 lb percu yd (0.77 kg/m 3), corrosion of reinforcement willoccur in most bridge deck concrete .35

Fig. 2 - Corrosion detector (courtesy Federal High-way Administration).

Epoxy resin injection with the delaminated con-crete in place may be used for repair where exces-sive contamination has not occurred ;31 or delami-nated concrete may be removed and spa11 repairprocedures followed. If a successful repair is notmade, concrete above the delamination interface willeventually become dislodged and a spa11 will result.Licensee=Bechtel Corp/9999056100

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2.3 - SpallsA spall is defined as the depression resulting

when a fragment is “detached from a larger mass bya blow, by the action of weather, by pressure, or byexpansion within the larger mass.,,6,7 A typical spallis shown in Fig. 3. Spalls are referred to as largewhen their size exceeds approximately 3/4 in. (19mm) in depth or 6 in. (152 mm) in any dimension 7,9

Fig. 3 - A typical spalled area (courtesy NationalResearch Council, Transportation Research Board).

The major cause of spalls is the same as that fordelaminations. A special case of spalling that occursat joints may be caused by corrosion of steel at ex-pansion dams, or from traffic impact, or intrusion ofmaterial into an unarmored joint. A spalled jointtemporarily filled with asphalt is shown in Fig. 4.Movements due to temperature fluctuations may al-low such filler to work its way deeper into the jointresulting in forces which frequently cause increaseddamage.

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Fig. 4 - Joint spall temporarily filled with asphalt(courtesy Portland Cement Association).

Although the extent of spalling may be visuallydetermined, potential spalling and the activity ofcauses of deterioration should be investigated as dis-cussed in Section 2.2. Usually the area of active steelcorrosion and chloride-contaminated concrete is con-siderably larger than the area of spalled or delami-nated concrete. If only the area of spalled or delami-nated concrete is removed and repaired, acontinuing repair program will probably be required.However, if the concrete that is supporting activecorrosion or is capable of supporting corrosion is re-moved and the repaired deck is properly protectedwith a waterproof membrane, bonded topping oroverlay; a more durable repair will probably be ob-tained. 14

Small isolated spa11 areas can be patched usingany of the materials discussed in this Guide that donot contain coarse aggregate. Larger areas can bepatched with concrete. When substantial areas areinvolved, overlays of dense portland cement concreteor latex modified portland cement concrete shouldbe considered.

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2.4 - ScalingScaling of concrete surfaces is defined as “local

flaking or peeling away of the near surface portionof concrete or mortar .

,,6,77 A scaled concrete surfaceis shown in Fig. 5.

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Light scaling refers to loss of surface mortar withno exposure of coarse aggregate. Medium and se-vere scaling refer to loss of mortar with increasingexposure of coarse aggregate. Very severe scalingrefers to loss of coarse aggregate with the mortar.

The most generally accepted explanation of scalinginvolves the generation of internal pressures duringfreezing of the solution contained in saturated voids.To explain observed increases in severity of deterio-ration attributed to the use of deicing chemicals, theosmotic pressure theory has been postulated . 7,8,9

Also, it has been shown that deterioration closelyresembling scaling from freeze-thaw action can occurwithout freezing when concrete is subjected eitherto cycles of wetting and drying or to concentratedsolutions of chloride deicers. Such attack can occurbeneath asphaltic concrete overlays which are usu-ally permeable to water. 10,11

Although the extent of scaling may be visually de-termined, measurement of the chloride ion content of the concrete is advisable to evaluate future spall-ing potential.

Surface coatings [less than 1/4 in. (6 mm) thick]have been used when scaling is in its earlystages. 18,37 Since delaminations frequently occur withsuch coatings, overlays of greater thicknesses arerecommended.

2.5 - Cracked or fractured sections of concretemembers

Only cracking that may potentially endanger thestructural adequacy of the member should be consid-ered for repair. Many cracks do not require repair.Some cracks cannot be repaired. If the crack widthis increasing due to continuing overloads or due tostructural settlement, complete replacement of thee=Bechtel Corp/9999056100

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member or some modification may be necessary. Ifthe crack width is changing with temperaturechanges or load cycles and action is necessary, thecrack should be treated as a joint and sealed.46 Mostrepairable cracks are the result of impact on themember or a one-time overloading. Cracks in pre-stressed members should not be repaired withoutconsultation with an engineer to determine the rea-son for the cracks.

It may be necessary to measure or estimate crackwidths. This can be done with measuring micro-scopes or feeler gages. If necessary, the extent ofcracking can be evaluated by pulse velocity tech-niques (ASTM C597) or by coring.

Fractured sections are differentiated from crackedmembers in that a portion of the member has be-come displaced. Repairable damage of this type mostoften occurs on parapets or facia walls as a result ofvehicle impact.

Epoxy resins generally can be used to repaircracks and bond fractured sections. It may be conve-nient to rout or widen cracks and then to fill with la-tex mortar if an overlay of latex mortar is to beused.

2.6 - RuttingRutting is defined as removal of concrete in wheel

paths as a result of abrasion by vehicle tires. Rut-ting has become more prominent with the advent ofstudded tires. The extent of rutting is visually ap-parent.

Shallow rutting may be repaired with an epoxyresin coating,18,37 but such a repair may have a lim-ited life. More extensive rutting, or shallow ruttingcombined with other damage, may make an overlaydesirable.

2.7 - Repair material characteristicsPortland cement concrete used in a repair will

have properties in its hardened state nearly thesame as those of the older in-place concrete. How-ever, if there is a difference in aggregate source,maximum aggregate size, or water content, proper-ties will differ and the in-place concrete will proba-bly have previously undergone drying shrinkage.Differential volume changes between a repair andthe in-place concrete will almost certainly occur. Ef-fects of differential volume change will generally beminimized by maximizing aggregate content, andminimizing water content within the limits of goodproportioning practices and by following good curingprocedures.

The inclusion of latex in a concrete or mortar maybe used to reduce the water-cement ratio and withthat reduced water-cement ratio, the long termproperties of the hardened latex concrete will besimilar to conventional concrete with the same ce-ment content. However, chloride ion ingress into the latex modified concrete will be reduced.

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Epoxy resin compounds have high adhesion, andhigher tensile strength and thermal coefficient thanportland cement concrete. This tends to induce fail-ure in repaired concrete immediately below thebonded interface when subject to large temperaturechanges. Epoxy resins are generally compoundedwith agents to decrease stiffness so as to relievestresses due to differential volume change. The in-clusion of aggregate will reduce the thermal volumechanges.

Methyl methacrylate polymer concrete propertiesare similar to those of epoxy resin concrete. Themonomer can penetrate dried in-place concrete andwill strengthen it after polymerization takes place.

Polymer concretes require the use of surface-dry,and preferably oven-dry, aggregate. Since the mono-mers for user formulated systems have very low vis-cosities, all forms and other boundaries of the place-ment must be sealed tight. Prepackaged methylmethacrylate materials that handle like mortars areavailable.

Portland cement and latex modified portland ce-ment mortar and concrete repairs generally requirecuring for 3 to 4 days. However, Iowa has exposedpartial depth patches of low slump, high cement con-tent concrete to traffic in 3 to 4 hr.

Epoxy resins are available in a variety of formula-tions for use at different temperatures. The curingrate of epoxy resins is temperature-dependent sothat strength development will vary. Traffic cangenerally be permitted in 6 hr, or less.

Rapid curing methyl methacrylate concretes mayaccommodate traffic 2 hr after placement. Poly-merization times are affected by the formulation,ambient temperatures at placement, and curing pro-cedures.


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Chapter. 3 - Surface preparation

3.1- ScopeSurface preparation is defined as the process of

making ready the contact surfaces of the existingconcrete for, (1) repair of scaled and/or spalledareas, (2) patching of sections where sound but chlo-ride-contaminated concrete has been removed fromareas adjacent to reinforcing steel, and (3) construc-tion of complete bridge deck overlays . Method s arerecommended for preparing those surfaces so thatthe repair material-will be properly bondedstructurally sound and durable repair.

3.2 - Removal of deteriorated concreteThe basic requirement for success of any repair is

proper preparation of the existing concrete. Re-gardless of the type or position of the bridge mem-ber, or the type of repair to be made, all unsoundand disintegrated concrete must be removed. Con-crete contaminated with chlorides must be givenspecial consideration for removal. Removal of all con-crete that shows evidence of active or potential cor-rosion will more nearly guarantee a durable repair.

to give a

Top edges of the areas to be patched should besharp but corners should be rounded to make it eas-ier to obtain good contact between the substrate andpatch material. Edges of patch areas should be un-dercut to eliminate feather edges and to provide akeyed patch. If a saw cut is made, the cut can betilted by placing one wheel of the saw carriage on aplank. The saw cut should not overrun the area tobe patched nor should it be so deep as to cut re-inforcing. Fig . 10a shows a deteriorated area beingcut out with a saw. Since the extent of unsound con-crete is frequently not evident from initial sounding,saw cutting can become a tedious and expensive op-eration. A satisfactory patch edge can be obtainedwith a chipping hammer.

Chipping tools must be selected such that theywill not damage surrounding areas. Where unneces-sarily heavy equipment and/or sharp-edged orpointed tools are used, possible damage to the sur-rounding concrete can create additional areas of po-tential failure. Selection of equipment may be basedon the difficulty encountered in removing materialbut it is recommended that 30 lb (14 kg) be the max-imum hammer weight. Gad points are better thanchisel points because they leave a rougher texturefor bond and a chisel inserted in a crack is likely tocause an extension of the crack.

Where only partial-depth patching is required ad-ditional limitations on air hammer weights and spe-cial instructions to hammer operators should bemade to avoid breaking through the deck or fractur-ing the concrete below the partial-depth patch area.Special care should be applied in removing unsoundconcrete from around reinforcing steel and em-bedded anchorages (such as for expansion joint steel

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shapes) to prevent loss of bond in the remainingsound concrete.

Large areas requiring the removal of a relativelythin layer of concrete, such as in shallow scaleddecks, may be more effectively treated with a scab-bler, scarifier, or planer than with chipping ham-mers. These machines are particularly effective incleaning a deck by removing the top surface con-tamination of traffic oils and greases. A scarifiedsurface is shown in the lower right portion of Fig. 6.Improper use of a scarifier may create small frac-tures in the base concrete.

3.3 - Reinforcing steelDelaminated areas and spalls sometimes extend to

or beyond the reinforcing steel. Care should be exer-cised in the use of saws and other power tools toavoid damage to the steel. If removal of material hasexposed more than half of the perimeter of a re-inforcing bar, it is recommended that the bar becompletely exposed with sufficient clearance underthe bar to assure encasement and bond. Steel shouldbe clean. For concrete patches, loose, scaly rustmust be removed; thin, tightly-bonded rust need notbe removed. Bits of mortar, if hard and sound, canbe left if they tightly adhere to the steel.

Steel, in areas to be patched with materials othertha n portlan d cement concrete, should be clean anddry with no loose scale, rust, mortar, or other mate-rial. Sandblasting is the most effective cleaningmethod.

Where reinforcing steel is to be cut and replaced,lap splices with accepted lap lengths as determinedby an engineer are preferred. If welding is used, itmust conform to the Structural Welding Code - Re-inforcing Steel (AWS D1.4).

3.4 - Cleaning of area to be repairedAfter removal of unsound concrete, the area

should be flushed with high pressure water or vac-uum cleaned to remove loose particles and dust. Airblowing may be effective, but the compressor shouldbe equipped with a functioning oil trap to preventcontamination.

All concrete surfaces on which new materials areto be bonded must be clean. Tar and asphalt shouldbe removed by mechanical methods and the surfaceshould then be sandblasted. Any asphalt or oil willinterfere with methyl methacrylate polymerization.Strong detergents, such as sodium metasilicate ortrisodium phosphate, may be useful in removing sur-face oil contamination, however, oils that have pene-trated the surface should be removed by chipping orscarification. The chipped surface often retains par-ticles that have been broken but not dislodged.These particles should be removed by high-pressurewater jetting or sandblasting.

Linseed oil mixtures are sometimes used on decksto prevent scaling. These mixtures penetrate con-crete to depths of about 1/16 in. (2 mm). Scarifica-

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Fig. 6 -Scarified surface (lower right). (courtesyPortland Cement Association)

tion to a depth of 1/4 in. (6 mm) is sufficient to re-move linseed oils and traffic oils that havepenetrated the concrete surface. Final cleaningshould be done immediately before placement of newmaterial to be sure that all contamination that mightinterfere with good bond is eliminated.

3.5 - CracksCracks in horizontal surfaces that are to be filled

with epoxy by gravity flow should be free of dust,oil, disintegrated material, or any debris that couldblock the free flow of the resin. The top surfaceedges should be chipped or sawed to form a smalltrough to provide an inlet for gravity flow of resininto the crack.

A minimum preparation as described in the follow-ing steps should be required for pressure groutingwith epoxy:

1. The surface along the crack must be clean. Achemical, mechanical, or waterblasting method canbe used to remove dried mud, grease, or other for-eign material. Concrete coatings, such as paint,should be removed. Care must be exercised to keepdebris from contaminating the crack.

2. Loose debris at or near the surface of the crackshould be blown out with an air jet, free of oil andmoisture, from a 75 to 100 psi (0.5 to 0.7 MPa)source. Any large, loose particles should be removedby hand.

3. The crack must be dry unless special formula-tions for wet concrete are used.

4. If drilling is necessary, vacuum drill bits are ad-visable to prevent drill dust sealing off narrowcracks.

Cracks to be filled with latex modified mortarshould be routed out to a depth of at least 2 in. (51mm) and then cleaned by air, water, or sandblasting.

Chapter 4 - Portland cement concrete

4.1 - GeneralRequirements for repair concrete are generally

the same as for original construction1 except for re-strictions to limit traffic obstruction time and to min-imizing differential volume changes.

4.2 - Materials and proportionsCement should be ASTM C150, Type I, II, or III.

Aggregate should conform to ASTM C33. Fine ag-gregate should have a substantial silica content ifthe concrete is to provide the traffic surface. Thenominal maximum size of the coarse aggregateshould be less than l/3 of the patch or overlaydepth. Air-entraining admixtures should conform toASTM C260 and chemical admixtures should con-form to ASTM C494. The use of accelerating admix-tures45 may be advantageous, but the admixture it-self should not contain more than 1 percent chlorideion by weight and the resulting total concrete mix-

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ture should not contain more than 0.1 percent chlo-ride ion by weight of cement. Tests to determinecompatability of admixtures and the specific cementunder job conditions are advisable before repairs arestarted.

Slump of mixes for shallow patches and overlaysshould not exceed 1 in. (25 mm). The slump of mixeswhich are to be consolidated around reinforcing steelby internal vibration should not exceed 3 in. (75mm). The water-cement ratio should not exceed 0.45by weight, and lower ratios are preferred. Mixeswith 3/8 or l/2 in. (10 or 13 mm) nominal maximumsize aggregate will require approximately 700 lb ofcement per cu yd (420 kg/m3). The Iowa Departmentof Transportation has developed a successful systemusing 823 lb per cu yd (488 kg/m3) with a water-ce-ment ratio of approximately 0.35. For mixes with3/8 or 1/2 in. (10 or 13 mm) nominal maximum sizeaggregate the air content should be 8 + 1 percent.

The low slump mixes recommended for partialdepth patches and overlays require a bonding agent.Licensee=Bechtel Corp/9999056100 Not for Resale, 05/04/2005 03:12:25 MDT

Fig. 7 - Application of epoxy resin bonding agent inpreparation for concrete overlay (courtesy AdhesiveEngineering Company).


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The bonding agent may be a portland cement or la-tex modified portland cement grout, or an epoxysystem.

The portland cement grout should consist of amixture of one part cement to 3/4 or 1 part fine ag-gregate conforming to ASTM C144, and sufficientwater to make a “heavy cream” consistency. Othergrouts or bonding agents should be used accordingto manufacturers’ recommendations, Application ofa portland cement grout is shown in Fig. 1Oc andthat of an epoxy resin bonding agent is shown inFig. 7.

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No definitive requirement exists for bond strengthof patch or overlay materials. A number of teststhat give relative strengths of bond in direct tensionand in direct shear have been reported.5,20,21,22 Fig. 8illustrates the test used in Reference 22. Other testprocedures are sometimes used for latex modifiedmaterials.23 The shear test referred to in Reference23 is illustrated in Fig. 9. A test method for eval-uating adhesion of epoxy resins to existing concretesurfaces is described in Appendix A of Reference 18and in Reference 37. An indicated absolute minimumtensile bond strength of 100 psi (0.69 MPa) is re-quired.

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Fig. 8 - Direct tensile test for bond strength ofoverlay (courtesy Federal Highway Administration).

Fig. 9 - Shear test for bond strength of overlay(courtesy Dow Chemical USA).ensee=Bechtel Corp/9999056100

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4.3 - Batching and mixingAccurately batched and properly mixed concrete

is essential to the success of patches and overlays.Since careless batching practices appear to be preva-lent on small jobs, prepackaging at the maintenanceshop or other convenient location should be consid-ered. If the aggregate cannot be completely dried, itmust be packaged separately from the cement. Con-ventional nontilting rotating drum or truck mixersare generally not suited for less than 2 in. (25 mm)slump concrete. Paddle or pugmill type mixers arerecommended. Equipment capable of batching andmixing concrete i n accordance with ASTM C685should be considered.

Temperature of the concrete mix should be be-tween 50 and 85 F (10 and 29 C), and it should notvary more than approximately 10 F (6 C) from thetemperature of the concrete against which it isplaced.

4.4 - Full depth patches and formed repairsBottom forms for full-depth patches may be sup-

ported by the adjacent deck, girders, or floor beams.Repairs to beams and rails sometimes require form-ing of repair material. Although forming may not begenerally extensive, recommendations of ACI Com-mittee 347, Formwork for Concrete,19 should be fol-lowed. The forms should be mortar-tight and clean.Consideration should be given to the texture im-posed by the forms on exposed surfaces.

Consolidation should be by systematic internal vi-bration. Finishing should be accomplished by con-ventional methods of screeding, floating, and tex-turing, if required.

4.5 - Partial depth patchesConcrete placed in partial depth patches should be

consolidated by tamping or vibrators, or both incombination. Placement and consolidation of lowslump concrete are difficult, but result in superior

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Copyright Provided bNo reprod

patches. Hand tamps should have a face area of notmore than 36 sq in. (0.02 sq ml. A vibrator com-pactor and a circular power float should be consid-ered for finishing if the area to be covered is exten-sive. These power tools should be operated in adirection parallel to the bridge centerline as much aspossible. When finishing along edges against existingold concrete, the trailing edge of the float should bemoving toward the old concrete. A final textured fin-ish is given by brooming perpendicular to the cen-terline.

Steps followed by the Iowa Department of Trans-portation for patching a concrete deck are shown inFig. 10a through f.

(a) Saw cut around the area ofdeterioration.

American Concrete Institute y IHS under license with ACI

uction or networking permitted wit

(b) Remove unsound material.
(c) Scrub in grout for bonding.
( d ) Prepare no-slump patch con-crete.

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(e) Place the concrete. (f) Compact the concrete.
Fig. 10 - Patching procedure used by Iowa Department of Transportation.Licensee=Bechtel Corp/9999056100 Not for Resale, 05/04/2005 03:12:25 MDThout license from IHS

4.6 - OverlaysIt is recommended that bonded overlays be 11/2 in.

(38 mm) or greater in thickness. Overlays of variablethickness may create problems of finishing to a uni-form grade-line, and of cracking at the boundary be-tween patched areas and the original deck. Suchproblems may occur when a patch and an overlayare placed in one operation without allowing thepatch time for settlement shrinkage. This situationwill be particularly aggravated if the patch is thickerthan 2 in. (50 mm). In such cases, a two-step place-ment procedure is recommended wherein thepatches are placed and consolidated at least 2 hr be-fore the overlay.

Concrete should be shoveled into place after it isdumped to prevent segregation. This is especiallyimportant at headers, near hubguards, curbs, and

construction joints, or where new concrete meets oldconcrete. Concrete should then be worked down andconsolidated by vibration or tamping, or a com-bination of both. A vibrating or oscillating screedshould be used for strikeoff and added consolidation.Iowa requires that the oscillating screed be at least5 in. (127 mm) wide and weigh at least 75 lb per sqft (366 kg/m2) of face area. Since adequate consoli-dation cannot always be assumed, it is recommendedthat the density of the consolidated material be de-termined.28 Final finish is to provide a proper tex-ture.

Steps followed by the Iowa Department of Trans-portation for applying a portland cement concreteoverlay are shown in Fig. lla through llf.

4.7 - ShotcreteShotcrete is especially adaptable to patching large

expanses of shallow scaled or spalled beams, piercaps, curbs, and undersides of decks. Detailed rec-ommendations are given by ACI Committee 506.24

Kulberg has discussed its use in restoring large shal-low deteriorations in dams.4 Development of equip-ment and techniques for shotcreting24 are discussedby Coy,25 Shideler and Litvin,41,42 and others.43 Ashotcrete patch is shown in Fig. 12.

Surface preparation is similar to that for other re-pair methods as given in Chapter 3. One additionalrequirement is that concrete be removed to form ashape that will not entrap rebounding materials. An-chor bolts may be used to tie new material to theold concrete.


CopyrProvidNo rep

(a) Scarify the surface.

ed by IHS under license with ACIroduction or networking permitted without license from IHS

,,`,`,,`

(b) Remove unsound material.

Licensee=Bechtel Corp/999905610Not for Resale, 05/04/2005 03:12:2

(c) Clean around reinforcing steeland follow with compressed aircleaning.

(d) Scrub in grout for bonding.

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(e)4 Workof screed.

no-slump concrete ahead

05

(f) Finish and apply curing com-pound.

Fig. 11 - Portland cement concrete overlay procedure used by Iowa Department of Transportation.

---

An area to be repaired by shotcreting should beprepared by chipping or sandblasting, then wettedand allowed to damp dry just before the shotcrete isapplied. No initial application of cement, cementgrout, or wet mortar should be used.

On overhead or vertical surfaces, shotcrete mustbe applied in layers with a delay of 30 min or morebetween placement of successive layers to avoid sag-ging and loss of bond. Proper curing conditions needto be maintained. Prior to applying succeeding lay-ers, surfaces that have taken final set can besounded for “drummy” areas that may result fromrebound pockets or lack of bond. Defective areasshould be cut out and replaced with the succeedinglayer.

4.8 - CuringWith low water-cement ratio repair concrete, a

continuous water cure is the preferred method forstrength development. The most practical method isthe application of a saturated absorbent material.Saturated burlap covered by sheet material to pre-vent evaporation of water is suggested. If the con-crete is wetted just before covering, sheet materialalone is effective. Sheets should be lapped to main-tain moisture control.ight American Concrete Institute

Sheet material can be prevented from being liftedby the wind by using sand or dirt for weight. Finesand is preferable because it will retain more waterif it is wet down for cooling.26 Dirt may create atraffic hazard in adjacent lanes.

Curing compounds conforming to AASHTO Ml48or ASTM C309 may be used. However, neither fur-nish desirable external water to low water-cementratio mixes nor do they provide any cooling effect.They should not be used if additional material is tobe later bonded to the surface being cured. Curingcompounds should be applied at twice their usualrate to shotcrete and to other rough textured sur-faces. It is essential that freshly placed surfaces bekept moist until curing is initiated. A fog spray or amonomolecular film should be used if there is to beany delay in application of curing compounds.

Partial depth patches may be opened to trafficwhen the concrete compressive strength is 1000 psi(7 MPa), however, greater strengths are desirable.Full depth patches should be cured without exposureto traffic until the concrete has attained a com-pressive strength of 3000 psi (21 MPa) or the designstrength, whichever is greater. Overlays should becured for a minimum of 3 days. For hot or coldweather concreting, recommendations in References26 and 27 should be followed.

MDT



Fig. 12 - Shotcrete repair (courtesy National Research Council, Transportation Research Board).t American Concrete Institute by IHS under license with ACI Licensee=Bechtel Corp/9999056100

Not for Resale, 05/04/2005 03:12:25 MDTduction or networking permitted without license from IHS

Chapter 5 - Latex modified portland cementmortar/concrete

5.1 - GeneralThis repair material consists of a portland cement

mortar or concrete that has been modified by the ad-dition of a latex emulsion.

5.2 - Materials and proportionsSynthetic latexes that have been found useful in

portland cement mortars or concretes are: polyvinylacetates, acrylics, styrene-butadiene, and vinylidenechloride. The last three are particularly suitable forwet environments.

The formulated latex modifier must be stabilizedto be compatible with the alkaline environment ofportland cement and to inhibit formation of exces-sive air in the composition. All stabilizers should beincorporated into the modifier at the point of manu-facture.

The particular latex modifier will have an in-fluence on the strength and the durability of the con-crete. Selection of the modifier should be based onanticipated service conditions. Reference 36 providesprequalification procedures for styrene-butadiene la-tex modifiers. Such procedures have not been devel-oped for other latexes.

Portland cement should conform to ASTM Cl50,Types I, II, or III, with one additional requirement.At a water-cement ratio of 0.40 or less, concrete us-ing the cement and latex modifier should not containmore than 9 percent air as measured by ASTM C231or C173. This will require that the selected cementand latex be compatible.

Aggregates should conform to ASTM C33 with anominal maximum size of 1/2 in. (13 mm) for concretemixes.

Latex modified mortar, recommended for sections1/2 to 11/4 in. (13 to 32 mm) deep, should have propor-tions of 1.0 part cement to 3.0-3.5 parts fine aggre-gate by weight. The water-cement ratio should be0.30-0.40 with a latex solids-cement ratio of 0.10 to0.20, both by weight.

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Latex modified concrete, recommended for sec-tions 11/4 in. (32 mm) and deeper, should have pro-portions of 1.0 part cement to 2.5-3.1 parts fine ag-gregate to 1.4-2.0 parts coarse aggregate by weight.The water-cement ratio should be 0.30-0.40 with a la-tex solids-cement ratio of 0.10 to 0.20, both byweight. The slump should be 4 to 6 in. (102 to 152mm).

5.3 - Batching and mixingFor small volume work, 5 to 10 cu ft (0.14 to 0.28

m3) batch mixers may be used to mix latex modifiedcompositions. All the latex and half the mixing wa-ter should be placed in a prewetted drum. With thedrum turning at minimum speed (16-18 rpm), aggre-gate and cement are next introduced, followed bythe remainder of mixing water. Total mixing timeshould not exceed 4 min at slow speed to prevent in-corporating excess air.

Continuous mixing type mixers complying withthe requirements of ASTM C685, should be used onall large area work requiring 4 or more cu yd (ap-proximately 3 or more m3) of mixed material.

Stationary batch type or continuous mixing typemixers must be capable of adequately blending themodified composition so that the freshly consolidatedmaterial contains not more than 9 percent entrainedair as determined by ASTM C231.

The temperature of latex modified compositions asplaced should be between 55 and 85 F (13 and 29 C)to minimize placement problems and maximize cur-ing efficiency. However, they can be placed at 45 F(7 C) when temperatures are rising, if adequate addi-tional cure-time is allowed to compensate for the lowtemperatures. Deicing chemicals should not be useduntil at least 30 days after the cure period hasended.

5.4 - PatchesPatches of latex modified portland cement compo-

sitions may be installed in thicknesses greater than1/2 in. (13 mm) but are not recommended in thinnersections.



Forms used in connection with full depth patchesshould be thoroughly treated with form release ma-terial. Some coatings will not perform well with la-tex modified concrete and, therefore, release agentsshould be evaluated prior to use.

The prepared concrete surface should be thor-oughly wetted with clean water for not less than 1hr prior to placement. After removing all free water,but with the surface still damp, sufficient mixed ma-terial to coat all bonding surfaces should be placedand vigorously broomed to assure maximum contactwith the old concrete and reinforcing steel. Addi-tional material is immediately added, consolidated,and screeded to the elevation required. The surfaceof the patch should then be given a textured finish.

5.5 - OverlaysA minimum thickness of 3/4 in. (20 mm) can be

used but 11/4 in. (32 mm) minimum thickness is pref-erable. Fig. 13a and b shows an overlay of latex-modified portland cement concrete composition beingplaced and cured. Existing expansion joints anddams should be maintained through the overlay byinstalling a bulkhead, equal in thickness to the widthof the joint, to the required grade and profile priorto placing the concrete. Treatment at expansiondams may consist of:

t American Concrete Institute by IHS under license with ACI L

Nduction or networking permitted without license from IHS

1. Welding a steel plate to the dam to raise it tothe elevation of the new surface, or

2. The overlay grade may be transitioned to meetthe existing dam where differences in elevation aresmall.

(a) Placing of 0verlay.

(b) Curing overlay.

Fig. 13 - Latex-modified portland cement, concretecomposition overlay (courtesy Dow Chemical USA).

When screed guides or bulkheads are required,they must be securely fastened in position to insurefinishing the new surface to the required profile.Screed rails should not be treated with a releasecompound because such treatment will prevent bondto the adjacent lane overlay.

The surface to be overlaid should be thoroughlywetted with clean water for not less than 1 hr andthen any puddles of free water blown clear. Theproperly mixed, latex-modified mortar should bepromptly delivered to the placement site and thor-oughly brushed onto the damp, prepared surface.Care should be exercised to ensure that all vertical,as well as horizontal surfaces, receive an even coat-ing. The rate of application of bonding materialshould be limited so that it does not dry before it iscovered with the overlay material required for finalgrade. The overlay should be struck off, consoli-dated, and finished to final grade with a vibratingscreed and/or rotating drum finisher. After a tight,uniform surface has been achieved, it should be tex-tured to provide an acceptable road surface. Thismust be done before excessive stiffening occurs toprevent tearing the surface. This may be within 20min in hot weather.

A construction dam or bulkhead is required whendelays in placement exceed 1 hr. During delays ofless than 1 hr, the end of the placement must beprotected from drying with several layers of wetburlap. Areas beyond the bulkhead will require anactive bonding coating when work is resumed.

Screed guides and/or construction dams should beseparated from the newly placed material by passinga pointing trowel along their inside face. This trowelcut must be made over the entire depth and lengthof rails or dams to facilitate their removal. Thetrowel cut should be made after the modified compo-sition has stiffened sufficiently to not flow into thecut. Screed rails in contact with overlay materialsmay be removed after the modified material hastaken initial set.

5.6 - CuringWhen exposed to conditions of evaporation, latex

particles coalesce to form a film. All finishing oper-ations must be completed and the surface coveredwith a single layer of wet burlap as soon as the sur-face will support it to prevent shrinkage crackingbefore this film has formed. Wax and resins found inmost curing compounds are incompatible with latexand should not be used without prior evaluation. The

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icensee=Bechtel Corp/9999056100 ot for Resale, 05/04/2005 03:12:25 MDT


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curing cover should be completed by placing a layerof polyethylene film on the wet burlap. This shouldbe left in place for 24 hr. At the end of 24 hr, thefilm and the burlap should be removed and the sur-face permitted to dry. The period of dry curing willusually be from 3-5 days and will depend on the typeof cement used and the curing environment. A min-imum compressive strength of 3000 psi (21 MPa)should be attained before opening to traffic.Strengths are generally determined using 2 in. (51mm) cubes for mortar and 3 by 6 in. (76 by 152 mm)cylinders for concrete.

Precautions should be taken to protect freshlyplaced modified material from rain. Placement oper-ations should be stopped if rain starts and any dam-aged material should be replaced.

Chapter 6 - Polymer concrete

6.1 - GeneralAlthough other materials have been used to make

polymer concrete, the most successful has been ei-ther an epoxy system with curing agents or methylmethacrylate monomer with an initiator and pro-moter. Epoxy systems are widely available in pre-pared formulations. Methyl methacrylate systemscan be formulated by the user or prepackaged sys-tems can be used.

6.2 - Epoxy concreteGeneral guidance on the use of epoxy systems is

given in the report of ACI Committee 503.18 Supple-mental guidance applicable to the repair of bridgesuperstructures is provided in this chapter.6.2.1 Materials and proportions - The epoxy systemshould conform to ASTM C881. Type, grade, andclass must be chosen to satisfy job conditions and re-quirements. Aggregates should be as recommendedby the epoxy formulator. The most generally usedaggregate is a silica sand with little or no materialpassing the No. 100 sieve. The maximum aggregatesize should be no more than 1/3 the thickness of thepatch or overlay. The aggregate should be clean anddry with a maximum moisture content of 0.5 percentby weight.

Epoxy mortars generally consist of 4 to 7 partssand to 1 part resin, by weight. The ratio may be in-creased by incorporating coarse aggregate propor-tioned with respect to sand as in portland cementconcrete. The ratio depends on combined gradation,particle shape, and resin viscosity. Proportioningstudies should determine density as well asstrength. To ensure durability, air voids should notexceed 12 percent.6.2.2 Batching and mixing - Accurately batched andproperly mixed material is essential. Batching maybe by weight or volume. The resin generally consistsof two components that are batched by volume andthoroughly mixed before the incorporation of aggre-

rican Concrete Institute S under license with ACI Li

Nn or networking permitted without license from IHS

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gate. Chemical reactions start as soon as the resincomponents are combined and the working time willdepend on the system, the temperature, and thehandling procedure. The user should be thoroughlyfamiliar with the particular system being used be-fore a large application is attempted.

Mixing of epoxy may be accomplished by hand forquantities less than 1 qt (0.001 m3), by low speeddrill or paddle for quantities less than 5 gal. (0.02m3), or by concrete mixer for larger quantities.When mixing by hand or low speed drill, the epoxycomponents should be mixed first. Sand should thenbe added to the mixed epoxy system. When mixingin a concrete mixer, the blended epoxy systemshould be added to the aggregate in the mixer.6.2.3 Patches and overlays - Any forms should becoated with a release agent compatible with theepoxy. All surfaces of concrete and steel should beprimed with neat resin. Placement and consolidationshould be done in layers of limited thickness as rec-ommended by the epoxy formulator. An epoxy mor-tar patch is shown in Fig. 14.

Fig. 14 - Epoxy mortar patch (courtesy NationalResearch Council, Transportation Research Board).ee=Bechtel Corp/9999056100

r Resale, 05/04/2005 03:12:25 MDT

6.2.4 Crack and fracture repair with epoxy resins -Reference 18 includes information on pressure in-jection of cracks that intersect surfaces, and Refer-ence 31 provides details on pressure injection into aseparation forming a delamination.

The epoxy system should conform to ASTM C881,Type I. The grade and class must be chosen to sat-isfy job conditions and requirements. The systemshould be capable of bonding to wet surfaces unlessit can be assured that the crack is dry.

Cracks ranging in width from 0.003 to 0.25 in.(0.08 to 6 mm) can be successfully filled. Crackswider than 0.25 in. (6 mm) generally require a sys-tem incorporating a mineral filler. Some cracks ex-tending downward from nearly horizontal surfacesmay be filled. by gravity. The minimum width ofcrack that can be filled by gravity is a function ofthe viscosity of the material. Generally the widthshould be at least 0.02 in. (0.5 mm) and the depthshould be less than 12 in. (305 mm).

ACI COMMITTEE REPORT546.1R-14

CopyrigProvideNo repr

Entry ports for pressure injection must be prop-erly spaced along cracks. While guidelines can begiven for proper spacing, good judgment must bethe final criterion. Guidelines for port spacing inpartial depth cracks are as follows:

1. Space ports at the desired depth of penetrationsince the resin generally travels as far into the crack

o

as along the face of the crack. If port to port travelat this spacing is not obtained, establish inter-mediate ports.

2. If the cracks are less than 0.005 in. (0.13 mm)wide, entry ports should never be spaced more than6 in. (150 mm) apart.

3. If the cracks are more than 2 ft (0.6 m) indepth, full penetration may be difficult to achievebecause of equipment limitations. Intermediate portsshould be established to monitor the flow of epoxy.

Guidelines for port spacing in cracks extendingthe full depth of the member are as follows:

1. For members 1 ft (0.3 m) or less in thickness,ports should be placed in the crack on one side onlyand spaced at the thickness of the member.

2. For members greater than 1 and less than 2 ft(0.3 and 0.6 m) in thickness, ports should be placedin the crack on all available sides and spaced nomore than the thickness of the member.

3. For members greater than 2 ft (0.6 m) in thick-ness, ports should be placed in the crack on all avail-able sides and spaced according to the guidelines setforth for partial depth cracks.

The first and last entry ports should be estab-lished at or near the bottom and top, respectively, ofany vertical crack, or at the ends of any horizontalcrack in a vertical or horizontal member.

If a fracture has resulted in one or two sectionsthat can be secured back in place, it may be repairedas a full depth crack. However, if the fracture hasproduced fragmentation, repair should be as detailedin Chapter 4.

Photographs of epoxy injection equipment areshown in Fig. 15 to 17. The pressure injectionmethod is illustrated in Fig. 18a and b. Pressure in-jection to bond delaminations is shown in Fig. 19.

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(a) Drill.

(b) Mixer and nozzle.

Fig. 15 - Equipment for expoxy resin injection(courtesy Kansas Department of Transportation).

ht American Concrete Institute d by IHS under license with ACIduction or networking permitted without license from IHS

Where appearance is important, lines or spills ofepoxy must be avoided or must be removed togetherwith surface seals from exposed surfaces.

6.3 - Methyl methacrylate concreteThis polymer concrete consists of aggregate com-

bined with a monomer which is polymerized in place.The material cures rapidly at ambient temperatures,usually develops compressive strengths of 5000 psi(35 MPa) or more within 2 hr of placement, andbonds well to concrete. 38,39 The chemicals used areflammable, may be toxic, and supervision must en-sure that safety precautions are observed.6.3.1 M a t e r i a l s and proportions - The methyl meth-acrylate (MMA) monomer system is preferred toproduce polymer concrete because of its low vis-cosity, high bond strength to concrete, and relativelylow cost. The individual components of PC can bepurchased and formulated by the user, or a pre-packaged system can be used. When MMA systemsare formulated by the user, promoter and initiatormust be added to the monomer system to causepolymerization within the desired time. Initiatorsare chemicals required to start polymerization andLicensee=Bechtel Corp/9999056100




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Fig. 16 - Hand operated pressure gun.

promoters are chemicals to accelerate poly-merization. Two monomer systems including pro-moters and initiators that have been used success-fully over a wide range of ambient temperatures areshown in Table 6.1. For thin repairs the surface tem-perature of the area to be repaired should be consid-ered along with the ambient temperature in select-ing the monomer system.

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Aggregate should conform to ASTM C33. The ag-gregate should be as dry as possible, with a pre-ferred maximum moisture content of 0.5 percent andnever to exceed 1 percent to attain compressivestrengths of 5000 psi (35 MPa) or more. The nominalmaximum size of aggregate should be no more than1/3 the depth of repair. One-half or 3/4 in. (13 or 19mm) nominal maximum size coarse aggregate can beused with approximately an equal weight of fine ag-gregate.

When using prepackaged systems, the promotersand initiators are preblended into the purchasedcomponents except with primers, which require theaddition of an initiator. Normally these products aresold with blended fine aggregates included. Themanufacturer’s instructions should be followed forproportioning of components, addition of coarse ag-gregates, and directions for use.6.3.2 Batching and mixing - Personnel handling andmixing monomers should use eye protection and im-pervious gloves and aprons; respirators with chem-ical filters should be available for those who wish touse them. A Class B fire extinguisher should be nearby. All personnel should be thoroughly trained inthe safe handling of these chemicals in accordancewith manufacturer’s recommendations. Mixing ofmonomers should occur in a shaded, well-ventilatedarea, free of ignition sources.

For user formulated MMA systems, monomersshould be mixed in a clean mixing vessel such as a 5gal. (0.02 m3) can or a 55 gal. (0.22 m3) drum. Explo-sion-proof electric mixers or explosion-proof com-pressed air-powered mixers should be used for mix-ing. After all monomers are mixed, the polymethylmethacrylate (PMMA), if required for thickening, isadded. If PMMA in powder form is used, enoughmixing time should be allowed for the PMMA tocompletely dissolve in the monomer mixture. IfPMMA syrup is used, only a short mixing time is re-quired. For small batches of monomer and for shortmixing times, nonsparking mixing paddles such aswood should be used.

All sources of fire, sparks, or excessive heat mustbe removed from the mixing area. Electrical equip-ment and drums should be properly grounded andall motors should be explosion proof. All mixing ves-sels must be kept clean of rust and other impurities.Copper or copper alloys must not be used in any ofthe vessels, plumbing, or mixing equipment thatcomes into contact with the monomer because ofpossible chemical reactions that can cause accidental

t American Concrete Institute by IHS under license with ACIduction or networking permitted without license from IHS

bulk polymerization. Spilled monomer should be con-tained with absorptive material such as sand or drysawdust and removed. The monomer system may bepremixed days or weeks prior to use in the field.However, the promoter and initiator should not beadded until the day the monomer is used.

At about the time the repair is to be made, prefer-ably not more than 1 hr ahead, the monomer shouldbe divided into two equal parts, A and B. The totalamount of initiator required for all of the monomershould be added to Part A. The mixture should bestirred until the initiator is thoroughly dissolvedwhich may take up to 30 min. The same safety pre-cautions as required for mixing the monomer shouldbe observed.

The promoter(s) should be added to Part B. Ifboth promoters are required, the dimethyl anilene(DMA) should be added first and stirred for 15 min.The dimethyl-p-toluidine (DMT) should then beadded and stirred for 15 min.

It is extremely important to be aware that theinitiator and promoters must never be mixed di-rectly together because of the danger of explosion.

For user-formulated monomer systems, two meth-ods of mixing and placing have been successfullyused. One method is to place premixed aggregateinto the repair hole and then pour the monomerover the aggregate. The second method is to premixmonomer and aggregate before placement. The first

Licensee=Bechtel Corp/9999056100 Not for Resale, 05/04/2005 03:12:25 MDT


Copyright AmeProvided by IH Lice

NotNo reproductio

rican Concrete Institute S under license with ACIn or networking permitted without license from IHS

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Fig. 17 - Pressure pot for epoxy injection.

nsee=Bechtel Corp/9999056100 for Resale, 05/04/2005 03:12:25 MDT

method is the simplest and usually requires lessequipment; the second method usually results in lesssegregation of aggregate and requires slightly lessmonomer.

When using prepackaged MMA systems, mortarsor concretes can be rapidly mixed by hand or ma-chine. The purchased liquid components are fully for-mulated and generally require no further processingby the user (except for adding initiator to primer liq-uids). If a rotating drum mixer is to be used to pre-pare materials, half of the coarse aggregate and allthe monomer or resin system should be added to themixer and mixed. The powders and fine aggregates,followed by the rest of the coarse aggregate, arethen added, and the entire blend is mixed for 2-3min. The material can be placed directly into the re-pair area, consolidated by vibrating and tampingwith conventional equipment, and finished with atrowel or broom. The manufacturer’s instructionsshould be carefully followed with special emphasison proportioning, safety, and cleanup.

Formwork must be used for full depth repairs, atexpansion or construction joints, or to establishgrade with asphalt overlays. Wooden forms shouldbe treated with a release agent especially made foruse with polymers, with vegetable oil, or with paraf-fin. All joints must be watertight for user formu-lated systems and mortartight for prepackaged sys-tems. Polyester putty (used for repairing autobodies), silicone, or latex caulking compound can beused to seal joints. Other sealants may be dissolvedor affect the polymerization reaction. It is recom-mended that the form be pretested for leaks with asmall amount of water the day prior to placement of

the polymer concrete, or with the monomer formula-tion if the repair is to be made the same day.6.3.3 Preplaced aggregate - This method is not gen-erally applicable to prepackaged systems, but it hasbeen widely used for user formulated MMA systems.Premixed aggregate is placed dry into the hole andscreeded to the required level. Part A of the mon-omer system is poured into Part B and stirred thor-oughly and then poured over the aggregate. Fig. 20shows pouring of the monomer over preplaced ag-gregate. A sprinkler can is recommended for smallor shallow repairs to minimize displacement of theaggregate. For larger repairs, monomer is pouredover the aggregate from large vessels or by spraybars attached to large drums. Since the pot life ofthe monomer may be less than 30 min, cautionshould be exercised to use all monomer within 10 to15 min after Parts A and B have been mixed to-gether.

Consolidation should be by tamping or vibration.Care must be taken to avoid separation of monomerand aggregate with vibration.

After monomer is ponded on the surface, the sur-face should be screeded smooth with sand added tolevel the surface. Areas of ponded monomer shouldbe filled with sand to prevent slick spots from occur-ring after the monomer polymerizes. The surface canbe finished with wooden floats or steel trowels. Fig.21 shows troweling a patch. Since monomers are vol-atile, the surface of the repair should be coveredwith a membrane such as polyethylene to reduceevaporation losses. This should be done as soon asthe surface has been finished. It may be necessary toadd monomer with a sprinkler can if evaporation,leakage, or other losses cause depletion of monomeron the surface. The aggregate should be kept in-undated with monomer until polymerization occurs.


Copyright AmeProvided by IHNo reproductio

(a) Before crack was sealed. (b) Pressure injection in progress.

Fig. 18 - Pressure injection entry ports.

ricS u nse

for Rn o

Fig. 19 - Pressure injection of epoxy resin to bonddelaminations in a bridge deck.

e=e

____________________

_______ ________

TABLE 6.1 - Examples of user formulated monomersystems for polymer concrete repair

ComponentsMonomer of monomersystem systems, by wt.

90% MMA

1 5% TMPTMA5% PMMA

90% MMA2

10% BA

Initiator, Promoter,percent of percent of Temperaturemonomer monomer range,

by wt. by wt. F (C)___ 3% BPO-70 1% DMA 35-70 (2-21)

1% DMT

2% BPO-70 1% DMA 70-95 (21-35)

4% LP 2% DMT 70-95 (21-35)

6% LP 3% DMT 40-70 (4-21)

MMA: methyl methacrylateTMPTMA: trimetholpropane trimethacrylate

BA: butyl acrylatePMMA: polymethyl methacrylateBPO-70: benzoyl peroxide (70% concentration)

LP: lauroyl peroxideDMA: dimethyl anileneDMT: dimethyl-p-toluidine

Bechtel Corp/9999056100 sale, 05/04/2005 03:12:25 MDT

6.3.4 Premixing and placing - This method hasbeen used for both user formulated and prepackagedsystems. For purposes of estimating quantities ofmaterials, MMA polymer concrete will consist of ap-proximately 88 percent by weight of aggregate and12 percent by weight of monomer for user formu-lated systems; however, prepackaged systems ex-tended with aggregate may use considerably lessmonomer. Small quantities of polymer concrete canbe mixed by hand in a pail or other container. Con-ventional concrete mixers can be used for largerquantities. Ready-mixed concrete trucks have beenused for projects requiring large quantities.

The required amount of aggregate should beplaced into the mixer and thoroughly mixed. The re-quired equal weights of parts A and B of the mon-omer system should be added together, stirredbriefly and poured into the mixer. Mixing shouldcontinue only until the aggregate is thoroughlywetted with monomer and then it is placed and con-solidated. Placing is shown in Fig. 22.

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Finishing is accomplished in the same manner asfor the preplaced aggregate method (Section 6.3.3).6.3.5 Polymerization - The monomer formulations shown in Table 6.1 usually provide 20 to 30 min ofworking time, although this time may be reduced ifthe monomer is not used immediately after parts A and B are mixed together, or if the ambient temperature is high. As polymerization proceeds, the sur-face temperature of the repair may reach temper-atures 50 to 100 F (30 to 60 C) higher than ambient.In some cases, especially where trimethyolpropanetrimethacrylate (TMPTMA) is not used, small sur-face blisters may occur on the surface. The surfaceblisters quickly wear off and do not have any ad-verse effects on the repair. Generally, the repair is

an Concrete Institute nder license with ACI Lice

Not r networking permitted without license from IHS

546.1R-18 ACI COMMlTTEE REPORT

Copyright AmProvided byNo reproduc

Fig. 20 - Pouring monomer over preplacedgate (courtesy University of Texas).

aggre-

Fig. 21 - Troweling the surface of a patch (courtesyUniversity of Texas).

Fig. 22 - Placing mixed polymer concrete (courtesyUniversity of Texas).

LicensNot fo

ready for traffic within 2 hr after the monomer isplaced.6.3.6 Cleaning of tools and equipment - Tools canbe wiped clean with a rag saturated with an organicsolvent such as trichlorethane. Cleanup of concretemixers can be performed by first rinsing with tri-chlorethane or with plain water followed by oper-ation of the mixer with a load of aggregate.6.3.7 Storage and handling of materials - Monomersused to produce polymer concrete are volatile, flam-

erican Concrete Institute IHS under license with ACItion or networking permitted without license from IHS

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mable, and potentially toxic materials. Constructionpractice has shown that such materials can be storedand handled safely by following reasonable pre-cautions. Manufacturers’ recommendations for stor-age and handling should be carefully followed. Refer-ence 40 also provides guidance for the safe use ofchemicals in polymer concrete.

Monomers should be stored in the containers inwhich they are shipped by the manufacturer. Thestorage temperature should not exceed 100 F (41 C).Ventilation should be provided to prevent buildup ofmonomer vapor concentrations in the storage area.

Initiators should not be stored in the same area asthe monomers or promoters. Initiators and pro-moters should be stored at temperatures recom-mended by the manufacturer.

Dry chemical extinguishers should be kept nearstorage areas and near the repair site. Water shouldnot be used to fight fires in monomers since it maycause the fire to spread.

Tops of empty monomer drums should never beremoved with burning torches or other sparkingequipment.6.3.8 Disposal of excess monomer - Monomer con-taining both promoter and initiator should be placedin open-top containers partially filled with aggre-gate. Loose-fitting plastic sheets should be drapedover the top of the container during polymerization.

Monomers containing initiator but no promotershould have 1 percent by weight of promoter addedto the monomer solution. Monomer with promoterbut no initiator should have 3 percent by weight ofinitiator added to the monomer solution.

After polymerization, the polymer can be disposedof like any inert material.

CHAPTER 7 - References1. ACI Committee 345, “Recommended Practice for Con-

crete Highway Bridge Deck Construction (ACI 345-74),, ,

American Concrete Institute, Detroit, 1974, 35 pp.2. Tuthill, Lewis H., “Conventional Methods of Repair-

ing Concrete,” ACI JOURNAL, Proceedings V. 57, No. 2,Aug. 1960, pp. 129-138.

3. Tremper, Bailey, “Repair of Damaged Concrete withEpoxy Resins,” ACI JOURNAL, Proceedings V. 57, No. 2,Aug. 1960, pp. 173-182.

4. Kulberg, 0. N., “Pneumatically Applied Mortar forRestoring Concrete Structures,” ACI JO U R N A L, Pro-ceedings V. 57, No. 2, Aug.-1960, pp. 183-192.

5. Felt, Earl J., “Repair of Concrete Pavement,” ACIJOURNAL, Proceedings V. 57, No. 2, Aug. 1960, pp. 139-153.

6. ACI Committee 116, Cement and Concrete Terminol-ogy, SP-19, American Concrete Institute, Detroit, 1978, 50pp.

7. ACI Committee 201, “Guide for Making A ConditionSurvey of Concrete in Service,” ACI JO U R N A L, P r o -ceedings V. 65, No. 11, Nov. 1968, pp. 908-918..

8. “Durability of Concrete Bridge Decks,” NCHRP Syn-thesis No. 57, Transportation Research Board, Washing-ton, D.C., 1979, 61 pp.

ee=Bechtel Corp/9999056100 r Resale, 05/04/2005 03:12:25 MDT


9. “Durability of Concrete Bridge Decks - A Coopera-tive Study, Report No. 6,” Publication No. EB067E, Port-land Cement Association, Skokie, 1969, 36 pp.

10. Neville, A. M., “Behavior of Concrete in Saturatedand Weak Solutions of Magnesium Sulphate or CalciumChloride,” Journal of Materials, Dec. 1969, pp. 781-816.

11, Browne, F. P.; Larson, T. D.; Cady, P. D.; and Bol-ling, N. B., “Deicer Scaling Mechanisms in Concrete,” ThePennsylvania State University, University Park, Dec.1970.

12. Moore, William M.; Swift, Gilbert; and Milberger, Li-onel J., “An Instrument for Detecting Delamination inConcrete Bridge Decks,” Highway Research Record No.451, Transportation Research Board, 1973, pp. 44-52.

13. Spellman, Donald L., and Stratfull, Richard F., “Lab-oratory Corrosion Test of Steel in Concrete,” Research Re-port No. M&R 635116-3, Materials and Research Depart-ment, California Division of Highways, Sacramento, 1968.

14. Clear, K. C., “Evaluation of Portland Cement Con-crete for Permanent Bridge Deck Repair,” Report No.FHWA-RD-74-5, Federal Highway Administration, Wash-ington, D.C., 1974, 48 pp.

15. “Durability of Concrete Bridge Decks - A Coopera-tive Study, Report No. 2,” Publication No. EB044E, Port-land Cement Association, Skokie, 1965, 107 pp.

16. “Rolling Pachometer, Operating Manual and Specifi-cation,” Office of Development, Federal Highway Adminis-tration, Washington, D.C., 1975.

17. Kliethermes, John C., “Repair of Spalling BridgeDecks,” (With Discussion by S. M. Cardone), Highway Re-search Record No. 400, Transportation Research Board,1972, pp. 83-92.

18. ACI Committee 503, “Use of Epoxy CompoundsWith Concrete,” ACI JOURNAL, Proceedings, V. 70, No. 9,Sept. 1973, pp. 614-645.

19. ACI Committee 347, “Recommended Practice forConcrete Formwork (ACI 347-78)," American Concrete In-stitute, Detroit, 1978, 37 pp.

20. Sinno, Raouf, and Furr, Howard L., “Bonded Con-crete Overlays,” Proceedings, ASCE, V. 96, ST8, Aug.1970, pp. 1627-1638.

21. Furr, Howard, and Ingram, Leonard, “ConcreteOverlays for Bridge Deck Repair,” (With discussion byJerry Shackelford and Harvey Shaffer), Highway ResearchRecord No. 400, Transportation Research Board, 1972, pp.93-104.

22. Pike, R. G., and Hay, R. E., “Polymer Resins as Ad-mixtures in Portland Cement Mortar and Concrete,” Re-port No. FWHA-RD-50, Federal Highway Administration,Washington, D.C., 1972, 56 pp.

23. Grenley, Dallas, and Kuhlmann, Lou, “Chemical Re-sistant Resurfacing Mortar for Industry,” Proceedings,ASCE, V. 100, C02, June 1974, pp. 133-140.

24. ACI Committee 506, “Recommended Practice forShotcreting (ACI 506-66) (Reaffirmed 1978)," AmericanConcrete Institute, Detroit, 1966, 7 pp.

25. Coy, William R., “Development of Equipment andTechniques for Pneumatic Application of Portland CementMortar in Shallow Patches,” Technical Report No. MRDL2-74, U.S. Army Corps of Engineers, Missouri River Divi-sion, 1974.

26. ACI Committee 305, “Hot Weather Concreting,”(305R-77), American Concrete Institute, Detroit, 1977, 16pp.Copyright American Concrete Institute Provided by IHS under license with ACINo reproduction or networking permitted without license from IHS

27. ACI Committee 306, “Cold Weather Concreting,”(306R-77), American Concrete Institute, Detroit, 1978, 22pp.

28. “Rapid Test Procedures, RT-13, Procedure for Mon-itoring the In-Place Density of Fresh Portland CementConcrete,” FWHA Notice No. N 5080.17, Federal High-way Administration, Washington, DC., June 11, 1974.

29. Pike, R. G., and Baker, W. M., “Concrete PatchingMaterials,” Report No. FHWA-RD-74-55,” Federal High-way Administration, Washington, D.C., 1974, 34 pp.

30. “AASHTO-FHWA SPEL. Special Product Eval-uation List.” Report No. FHWA-RD-78-41, Federal High-way Admininstration, Wahington, D.C., 1978.

31. Stratton, F. N., and McCollom, B. F., “Repair of Hol-low and Softened Areas in Bridge Decks by Rebondingwith Injected Epoxy Resin or Other Polymers,” ReportNo. K-F-72-5, State Highway Commission of Kansas, To-peka, July, 1974.

32. “Guide for Pressure Grouting Cracked Concrete andMasonry Structures with Epoxy Resin,” Department ofthe Army Technical Manual, Construction Engineering Re-search Laboratory, Champaign, Ill., 1971, 40 pp.

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

34. Smith, Mitchell D., “Fast Setting Concrete PatchingMaterial,” Report No. 73-06-1, Oklahoma Department ofTransportation, Oklahoma City, Dec. 1977.

35. Clear, K. C., “Time-To-Corrosion of Reinforcing Steelin Concrete Slabs, V. 3, Performance After 830 Daily SaltApplications,” Report No. FHWA-RD-76-70, Federal High-way Administration, Washington, D.C., 1977, 64 pp.

36. Clear, K. C., and Chollar, B. H., “Styrene-ButadieneLatex Modifiers for Bridge Deck Overlay Concrete,” Re-port No. FHWA-RD-78-35, Federal Highway Adminis-tration, Washington, D.C., 1978, 124 pp.

37. ACI Committee 503, “Standard Specification forBonding Hardened Concrete, Steel, Wood, Brick, andOther Materials to Hardened Concrete with a Multi-Com-ponent Epoxy Adhesive (ACI 503.1-79);” “Standard Specifi-cation for Bonding Plastic Concrete to Hardened Concretewith a Multi-Component Epoxy Adhesive (ACI 503.2-79);”“Standard Specification for Producing a Skid-ResistantSurface on Concrete by the Use of a Multi-ComponentEpoxy System (ACI 503.3-79);” “Standard Specification forRepairing Concrete with Epoxy Mortars (ACI 503.4-79),”American Concrete Institute, Detroit, 1979, 24 pp.

38. Fowler, David W., and Paul, Donald R., “Polymer-Concrete for Repair of Bridge Deck,” Proceedings, SecondInternational Congress on Polymers in Concrete (Austin,Oct. 19781, College of Engineering, University of Texas atAustin, 1979, pp. 337-350.

39. Kukacka, L. E., and Fontana, J., “ImplementationPackage 77-11, V. 1, Polymer-Concrete Patching MaterialsUsers Manuals,” Brookhaven National Laboratory, Upton,N.Y., Apr. 1977.

40. Fowler, David W.; Kukacka, Lawrence E.; Paul,Donald R.; Schrader, Ernest K.; and Smoak, W. Glenn,“Safety Aspects of Concrete-Polymer Materials,” Polymersin Concrete: International Symposium, SP-58, AmericanConcrete Institute, Detroit, 1978, pp. 123-138.

41. Shideler, J. J., and Litvin, Albert, “Structural Appli-cations of Pumped and Sprayed Concrete,” DevelopmentDepartment Bulletin No. D72, Portland Cement Associa-tion, Skokie, Jan. 1964, 29 pp.Licensee=Bechtel Corp/9999056100


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CopyrProvidNo rep

42. Litvin, Albert, and Shideler, Joseph J., “LaboratoryStudy of Shotcrete,” Shotcreting, SP-14, American Con-crete Institute, Detroit, 1966, pp. 165-184.

43. Shotcreting, SP-14, American Concrete Institute, De-troit, 1966, 223 pp.

44. ACI Committee 201, “Guide to Durable Concrete,”(201.R-77), American Concrete Institute, Detroit, 1977, 37pp.

45. ACI Committee 212, “Guide for Use of Admixturesin Concrete,” ACI JOURNAL, Proceedings V. 68, No. 9,Sept. 1971, pp. 646-676.

46. ACI Committee 504, “Guide to Joint Sealants forConcrete Structures,” (504R-77), American Concrete In-stitute, Detroit, 1977, 57 pp.

Chapter 8 - Applicable specificationsand standards

8.1 - ASTM Specifications and Standards (AmericanSociety for Testing and Materials, 1916 RaceStreet, Philadelphia, Pa., 19103)

C33-78

C144-76

C150-78a

Cl71-69Cl73-78

Standard Specification for ConcreteAggregates.Standard Specification for Aggre-gate for Masonry Mortar.Standard Specification for PortlandCement.Sheet Materials for Curing Concrete.Standard Test Method for Air Con-tent of Freshly Mixed Concrete bythe Volumetric Method.Tentative Test Method for Air Con-tent of Freshly Mixed Concrete bythe Pressure Method.Standard Specification for Air-En-training Admixtures for Concrete.Standard Specification for LiquidMembrane-Forming Compounds forCuring Concrete.

C231-78

C260-77

C309-74

ight Americaned by IHS unroduction or

C494-79

C597-71

C685-79

C823-75

C876-77

C881-78

Standard Specification for ChemicalAdmixtures for Concrete.Standard Test Method for Pulse Ve-locity Through Concrete.Standard Specification for ConcreteMade by Volumetric Batching andContinuous Mixing.Standard Recommended Practice forExamination and Sampling of Hard-ened Concrete in Constructions.Standard Test Method for Half CellPotentials of Reinforcing Steel inConcrete.Standard Specification for Epoxy-Resin-Base Bonding Systems forConcrete.

8.2 - AASHTO Standards (American Association ofState Highway and Transportation Officials,341 National Press Building, Washington, D.C.20045)

M148-78(C309-74)

M182-60

T259-78

Standard Specification for LiquidMembrane-Forming Compounds forCuring Concrete.Standard Specification for BurlapCloth Made From Jute or Kenaf.Standard Method of Test for Resis-tance of Concrete to Chloride IonPenetration.Standard Method of Test for Sam-pling and Testing for Total ChlorideIon in Concrete.

T260-78

8.3 - AWS Standard (American Welding Society,2501 N.W. 7th St., Miami, Fla., 33125)

D1.4-79 Structural Welding Code - Re-inforcing Steel.

Robert R. AndersonJohn E. BukovatzAnthony E. FioratoDavid W. FowlerHoward L. Furr

This report was submitted to letter ballot of the committee whichconsists of 16 members; 14 ballots were affirmative and 2 ballotswere not returned. It has been processed in accordance with theInstitute procedure and is approved for publication and dis-cussion.

ACI Committee 546

Guide for Repair of Concrete Bridge Superstructures

RUPERT E. BULLOCKChairman

Samuel B. HelmsLawrence F. KahnHarold C. KlassenLouis A. KuhlmannJames E. McDonald

Wallace T. McKeel, Jr.Williard F. Miller, Jr.Myles A. MurrayThomas J. Pasko, Jr.Richard J. Welton Concrete Institute

der license with ACI Licensee=Bechtel Corp/9999056100 Not for Resale, 05/04/2005 03:12:25 MDTnetworking permitted without license from IHS

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