503.5R-92

865

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Guide for the Selection ofPolymer Adhesives with Concrete

Reported by ACI Committee 503

ACI 503.5R-92(Reapproved 2003)

This guide provides the engineer, contractor, and architect with a descriptionof the various types of polymer adhesives (epoxy, polyester, acrylic,polyurethane, polysulfide, silicone, vinyl acetate, and styrene butadiene)most frequently used for adhesive bonding of fresh concrete to curedconcrete, repair of cracks in concrete, bonding concrete to other materials,and adhesive grouting of bolts and other inserts into concrete.

The guide emphasizes the factors that should be considered whenselecting a structural adhesive, including characteristics during installationand in service. The benefits and limitations of adhesive bonding arediscussed for each application.

Keywords: acrylic resins; adhesives; bolts; bonding; epoxy resins; fireresistance; fresh concrete; grouting; latex; loads (forces); methacrylate;plastics, polymers, and resins; polyester; polysulfide; polyurethane;repairs; sealing; serviceability; silicone resins; styrene-butadiene resins;toxicity; vinyl acetate; water-borne adhesives.

CONTENTSChapter 1—General, p. 503.5R-2

1.1—Organization of the guide1.2—Caution1.3—Advantages/disadvantages of adhesive bonding1.4—Glossary of terms

Chapter 2—Solvent-free adhesives, p. 503.5R-42.1—Application characteristics2.2—Properties during cure2.3—Properties of cured adhesive2.4—Distinguishing characteristics

Chapter 3—Water-borne adhesives (latex and latex powder adhesives), p. 503.5R-8

3.1—Application characteristics3.2—Properties of cured adhesive3.3—Distinguishing characteristics

Chapter 4—Adhesive selection criteria,p. 503.5R-10

4.1—Type and magnitude of loads4.2—Conditions during application

Milton D. Anderson* Paul R. Hollenbach Joseph A. McElroy* Hamid Saadatmanesh

Roger W. Black David P. Hu Paul F. McHale W. Glenn Smoak

John P. Cook T. Michael Jackson Peter Mendis* Joe Solomon

Floyd E. Dimmick Troy D. Madeley Richard Montani Michael M. Sprinkel

Wolfgang D. Eisenhut Albert Mayer Joseph M. Plecnik Douglas G. Walters*

Jack J. Fontana*

*Members of Subcommittee who prepared this report.

Raymond J. SchutzChairman

Robert W. Gaul*

Subcommittee ChairmanMyles A. Murray

Secretary

866 CONCRETE REPAIR MANUAL503.5R-2 ACI COMMITTEE REPORT

Chapter 5—Adhesive for bonding of hardened concrete to hardened concrete, p. 503.5R-10

5.1—Important application characteristics5.2—Important bond-strength considerations

Chapter 6—Adhesives for bonding of plastic concrete to hardened concrete, p. 503.5R-11

6.1—Important application characteristics6.2—Important bond-strength considerations

Chapter 7—Adhesives for repair of cracks in concrete, p. 503.5R-11

7.1—Important application considerations7.2—Important strength considerations

Chapter 8—Adhesives for bonding insertsinto concrete, p. 503.5R-12

8.1—Important application considerations8.2—Important strength considerations

Chapter 9—Adhesives for bonding concrete and other materials, p. 503.5R-12

9.1—Important application considerations

Chapter 10—Quick reference guide, p. 503.5R-14

Chapter 11—References, p. 503.5R-1411.1—Specified and/or recommended references11.2—Cited references11.3—Additional references

CHAPTER 1—GENERALThis guide is intended to aid the engineer, contractor, and

architect in choosing a proper polymer adhesive for adhesivebonding applications encountered in joining concretemembers in construction, repair, and rehabilitation ofconcrete structures.

1.1—Organization of the guideSections 2 and 3 of the guide describe the properties of the

two major classes of polymer adhesives in use (solvent-freeadhesives and water-borne adhesives) and identifies thedistinguishing features of the specific polymers (e.g., epoxy,acrylic, and polyvinyl acetate) within each class. Section 4lists the basic criteria that should be used in all adhesiveselections. Sections 5 through 9 provide additional guidancespecific to the selection of adhesives for bonding fresh orhardened concrete to hardened concrete, repairing crackedconcrete, bonding other materials to concrete, and bondinginserts into concrete. Section 10 is a quick reference guide tohelp narrow the search for a proper adhesive.

This guide includes more data and information on epoxyadhesives than on other types because epoxy adhesives arethe most versatile and by far the most widely used withconcrete. Information on other types is included where thereis a choice.

1.2—CautionThis guide presents data on the various polymer and

copolymer types (epoxy, polyester, acrylic, polyurethane,

silicones, vinyl acetate, and styrene-butadiene) either astypical values, as a range of values, or as relative values.Because of the ease of tailoring polymer products by formu-lation, some very special products within a group maypossess values for a particular characteristic that differwidely from the typical value or fall outside of the range. Toinclude all extremes would lead to a less accurate perceptionof the true nature of these groups of products as they arecommonly used. The cited characteristics of classes ofpolymer adhesives are only a guide to help narrow the fieldin a search for an appropriate adhesive.

When using an adhesive, the manufacturer’s literatureshould always be reviewed. Manufacturer’s recommendationsshould be followed because the adhesive may differ fromother adhesives in its class.

Many adhesives contain hazardous ingredients. MaterialSafety Data Sheets (MSDS) and labels should always beconsulted before using the adhesive.

1.3—Advantages/disadvantages ofadhesive bonding

The major advantage of adhesive bonding is that it allowsdistribution of an applied load over much larger areascompared to other methods of fastening, thus reducing theunit stress on the elements that are bonded. It allows attachmentwithout having to alter the shape or deface the elements to beattached. The adhesive bond line can also act as a moisturebarrier.1,2

The major disadvantage of adhesive bonding is that thebonded elements cannot be disturbed after being joined,because the adhesive cures for hours or days, depending onthe cure rate of the adhesive used and the temperature of theelements being bonded. Thus, work progress may be sloweddown if the other work tasks cannot be scheduled toaccommodate the adhesive cure time.

1.4—Glossary of termsThis glossary gives definitions of some terms that are used

in adhesive bonding in the concrete industry. Other termsmay be found in ASTM D 907.

accelerator—a material that increases the rate of achemical reaction.

acrylic—one of a group of resins formed by polymerizingthe esters or amides of acrylic acid.

adhesives—the group of materials used to join or bondsimilar or dissimilar materials; for example, in concretework, the epoxy resins.

age hardening—the progressive change in the chem-ical and physical properties of an adhesive, leading toembrittlement.

bond line—the interface between two surfaces bondedtogether with an adhesive.

catalyst—a substance whose presence increases the rateof a chemical reaction. In some cases, the catalyst isconsumed and regenerated; in other cases, the catalyst seemsnot to enter into the reaction, but functions by virtue of someother characteristic.

867SELECTION OF POLYMER ADHESIVES WITH CONCRETESELECTION OF POLYMER ADHESIVES WITH CONCRETE 503.5R-3

cohesive—the type of molecular attraction that holdsadhesives and other materials together.

cohesive failure—a failure by separation within the adhesiveitself, or within the substrate, rather than in the adhesive’sbond to the substrate.

copolymerization—polymerization of two or moredissimilar monomers.

crosslinking agent—a substance that increases themolecular weight of a polymer by chemically linking andbridging the polymer chains.

cure—to change the properties of a chemical (usually apolymer) by increasing its molecular weight by polymerizationor crosslinking, usually accomplished by the action of heat,catalyst, crosslinking agent, curing agent, or any combination,with or without pressure.

curing agent—a substance that accelerates or participatesin the curing of chemicals, sometimes referred to as ahardener.

elastomeric—pertaining to a substance that has rubber-like properties.

emulsion—a two-phase liquid system in which smalldroplets of one liquid (the internal phase) are immiscible in,and dispersed uniformly throughout, a second continuousliquid phase (the external phase).

epoxy resins—a class of organic chemical bondingsystems used in the preparation of special coatings or adhesivesfor concrete or as binders in epoxy resin mortars and concretes.

exothermic—pertaining to a chemical reaction thatoccurs with the evolution of heat.

flexibilizer—a substance that is mixed with a more brittlematerial to make the latter more ductile.

gel—a colloid in which the dispersed phase has combinedwith the continuous phase to produce a viscous jelly-likematerial.

glass transition temperature—the temperature or rangeof temperature at which polymeric materials change from arigid, glass-like state to an elastomeric-like state.

heat deflection temperature (HDT)—the temperature atwhich a plastic material reaches an arbitrary deflection whensubjected to an arbitrary load and test condition. It can be anindication of the glass transition temperature, although thesetwo temperatures are not necessarily equal.

initiator—a substance that causes a chemical reaction(such as polymerization or curing) to start. The term usuallyapplies to free-radical polymerization-type reactions.

latex—a dispersion of organic polymer particles in water.minimum film-forming temperature (MFFT)—the

lowest temperature at which the polymer particles of a latexhave sufficient mobility and flexibility to coalesce into acontinuous film.

monomer—an organic liquid, of relatively low molecularweight, that creates a solid polymer by reacting with itself orother compounds of low molecular weight, or both.

plasticizer—a substance added to polymer or copolymerto reduce its minimum film-forming temperature and/or itsglass transition temperature.

polyester—one of a large group of synthetic resins,mainly produced by reaction of unsaturated dibasic acids

with dihydroxy alcohols; commonly prepared for applicationby mixing with a vinyl-group monomer and free-radicalcatalysts at ambient temperatures and used as binders forresin mortars and concretes, fiber laminates (mainly glass),adhesives, and the like.

polymer—the product of polymerization; morecommonly a rubber or resin consisting of large moleculesformed by polymerization.

polymerization—the reaction in which two or moremolecules of the same substance (monomer) combine toform a compound containing the same elements, but of highmolecular weight.

polyol—a polyhydric alcohol, i.e., one containing two ormore hydroxyl groups.

polysulfide—synthetic polymers obtained by the reactionof sodium polysulfide with organic dichlorides.

polyurethane—reaction product of an isocyanate withanyone of a wide variety of other compounds containing anactive hydrogen group; used to formulate tough, abrasion-resistant coatings.

polyvinyl acetate—colorless, permanently thermoplasticresin; usually supplied as an emulsion or water-dispersiblepowder characterized by flexibility, stability toward light,transparency to ultraviolet rays, high dielectric strength,toughness, and hardness; the higher the degree of polymer-ization, the higher the softening temperature; may be used inpaints for concrete.

promoter—substances that, when added in small quantities,increase the activity of catalysts, as well as increase orpromote polymerization activity.

pseudoplastic—often referred to as thixotropic, asubstance whose viscosity decreases with increasing shear.

rheology—the science dealing with the flow of materials.silicone—a resin in which the main polymer chain

consists of alternating silicon and oxygen atoms, with carboncontaining side groups; silicones may be used in caulking orcoating compounds, admixtures for concrete, or as adhesives.

substrate—a material upon the surface of which an adhesiveis spread for the purpose of bonding.

surface-active agent—a substance that markedly affectsthe interfacial or surface tension of solutions even whenpresent in very low concentrations.

surface energy—the interfacial free energy per unit areaof the boundary between the surface of a substrate and the airabove it.

surface tension—a measure of surface energy, arisingfrom molecular forces at the surface of a liquid, that tend tocontain the volume to a minimum surface area.

surfactant—a contraction of the term “surface-activeagent.”

thermoplastic—becoming soft when heated and hardwhen cooled.

thermosetting—becoming rigid by chemical reaction andnot remeltable.

thixotroping agents—a substance incorporated into anadhesive to impart thixotropy.

thixotropy—the property of a material that enables it tostiffen in a short period of time on standing, but to acquire a


lower viscosity on mechanical agitation, the process beingreversible; a material having this property is termed thixotropicor shear thinning (see rheology).

vinyl ester—one of a group of synthetic resins producedby the reaction of acrylic with epoxy resin or Bisphenol A,and commonly prepared for application by mixing with avinyl group monomer and free-radical catalysts at ambienttemperatures, and used as binders for resin mortars andconcretes, and fiber laminates (mainly glass) adhesives.

viscosity—the property of a material that resists change inshape or arrangement of its elements during flow, and themeasure thereof—specifically, the ratio of the shear stressexisting between laminae of moving fluid and the rate ofshear between these laminae.

working life—the period of time when an adhesive, aftermixing with a curing agent or other ingredient, remains suffi-ciently workable to permit spreading and application.

CHAPTER 2—SOLVENT-FREE ADHESIVESSolvent-free adhesives cure by polymerization of monomeric

resins. Section 2.1 describes the characteristics of polymericadhesives prior to curing that are important in applying orinstalling the adhesive. Section 2.2 describes properties ofthese materials during and after curing that affect theirsuitability in achieving and maintaining an adhesivebond. Section 2.3 describes the features that distinguisheach of the polymeric adhesives.

2.1—Application characteristics2.1.1 Working life—Working life can vary from as little as

2 minutes to as long as 8 hours from one adhesive to anotherwithin each type of solvent-free adhesive. In general, thelonger the working life, the longer the curing time. Auto-matic metering and mixing equipment makes practical theuse of adhesives with a very short working life.3

The temperatures of the adhesive components, theambient temperature, and the substrates also influenceworking time. High temperatures shorten working time andlow temperatures lengthen working time.4 The polymerizationreaction is exothermic. Holding a mixed adhesive in a massin a mixing container increases the temperature of the adhesivebecause the beat cannot dissipate efficiently. This significantlyshortens the working life. Applying the adhesive to thesubstrate immediately after mixing lengthens the workinglife because most of the exothermic heat can be dissipatedinto the substrate without raising the temperature of theadhesive.

2.1.2 Curing—There are two mechanisms for curingadhesives. Epoxies and two-component polyurethanes cureby the chemical reaction of the base resin and a curing agent.Polyesters, one-component polyurethanes, methacrylates,polysulfides, and silicones cure by the addition of a catalystor release of a catalyst included in the formulation.5

The curing reaction of a monomer/curing agent is verytemperature-dependent.6 Lower temperatures extend thecuring time and higher temperatures shorten the curing time.Although special adhesives are available that will cure attemperatures down to 0 °F (–18 °C), most adhesives will not

effectively cure in a practical time at temperatures below40 °F (4 °C).

Catalytic curing is less temperature-dependent than themonomer/curing agent reaction, and the cure rate can beincreased by the addition of an accelerator.7

The adhesive must cure quickly enough to obtain strengthlevels that can resist stresses that develop from removal ofsupport of the bonded composite, or from temperaturechanges in the bonded composite; and from exposure tomoisture due to precipitation, tides, or other sources thatcould cause degradation.

2.1.3 Viscosity—Polymeric adhesives are available withviscosities ranging from 15 centipoise (cps) to a paste-likeconsistency. The viscosity of the adhesive depends on theinherent viscosity of the base monomers and curing agents,fillers, and thixotroping agents. The viscosity of any adhesivecan be lowered by raising its temperature. This can beachieved either by heating the adhesive itself or by heatingthe substrate.

2.1.4 Thixotropy—Very viscous adhesives are not neces-sarily thixotropic. When thixotropic properties of an adhesiveare desired, an adhesive must be chosen that has beenmanufactured to include thixotroping agents. Generally,high temperatures will lower the thixotropic characteristic ofthe adhesive and lower temperatures will increase the thixot-ropy, but is not affected to the same extent as viscosity bytemperature.8

Adhesives are available that will stand in a bond line asthick as 1/4 in. (6.4 mm) without external containment.

2.1.5 Toxicity and safety—Most components of solvent-free adhesives prior to curing have some degree of toxicityand some are flammable. Toxicity and hazard potentials varywidely from product to product. The manufacturer’s literatureand Material Safety Data Sheet (MSDS) for each productshould be consulted, and all cautions should be observed. Ingeneral, adhesives require the use of protective clothing, goodventilation, good housekeeping, and personal cleanliness.

2.2—Properties during cure2.2.1 Gel—Cure of an adhesive is accompanied by an

increase in viscosity and formation of a gel state before fullcure. In the gel state, the adhesive does not possess the physicalor chemical properties it will ultimately achieve. If the adhesiveis stressed during curing, irreversible damage can be done tothe bond with the substrate or the adhesive itself, resulting inlower strength.9,10

2.2.2 Exothermic reaction—The chemical reaction ofcuring is exothermic and can accelerate cure rate, resultingin the adhesive reaching the gel state at an elevatedtemperature. If this happens, internal stresses are induced inthe bond when the adhesive cools to normal temperature.

On a practical level, this condition occurs only in bondlines greater than 1/8 in. (3.2 mm) in thickness, because innarrow bond lines the heat dissipates into the substrates.

2.2.3 Shrinkage—All adhesives shrink when they cure.The addition of fillers to an adhesive system will reducevolumetric shrinkage but the inherent characteristics of aparticular polymer system have by far the greatest influence


on shrinkage.11 Volumetric shrinkage from the uncured tothe cured state varies from as low as 2% for filled epoxysystems to over 20% for some unfilled polyester systems.

Shrinkage works against good adhesion. It reduces theintimate contact between adhesive and substrate that isimportant for mechanical interlock and attraction of theadhesive molecules to the substrate surface; it also buildsinternal stress in the bond line.12

2.3—Properties of cured adhesive2.3.1 Bond strength—The strength of an adhesive bond

depends on:a. Adhesion of the adhesive to the substrate materials.b. Cohesive strength of the adhesive.c. Cohesive strength of the substrate materials.The bonded joint is only as strong as the weakest of these

three strengths.13,14

In all bonding/repair applications, the surface of the hardenedconcrete must be sound and clean. Grease and oil-typecontaminants will interface with the formation of a sound bond.

The condition and strength of concrete at the surface isparticularly important. If the larger aggregate is not exposed,the surface layer is considerably weaker than the concretebelow the surface. The application of low-viscosity primersimproves adhesion of solvent-free adhesives that are moreviscous or that have relatively poor molecular attraction toconcrete. The low-viscosity primer can provide more intimatecontact with the substrate, resulting in better adhesion.

Adhesive strengths with concrete are usually measured intension as a pulloff, in flexure in a bond line parallel with thedirection of the applied load, or in shear. The slant-shear testdescribed in ASTM C 882 is the most useful and commonlyused test. See Table 1 for typical adhesive bond strengths.

The pipe cap pulloff test described in ACI 503R-80,Appendix A, is useful for field testing adhesive bonds.

2.3.2 Tensile strength and elongation—Because of thehigher tensile strength of polymers relative to concrete, thetensile strength of an adhesive material itself is seldom acontrolling factor.

Tensile strength of adhesives is most commonly measuredby ASTM D 638. Tensile elongation as measured in ASTM D638 is an indication of the relative stiffness of the adhesive.

The numerical value determined in the test method forpercentage of elongation should not be taken as the elongationthat will take place in an adhesive joint. The elongation in the

test specimen is measured over a length of 1 in. (25 mm) withan initial cross section of 1/2 x 1/8 in. (12.7 x 3.2 mm) or less.As the test specimen is loaded, the cross section can becomesmaller without any external constraints. In an actual adhe-sive joint loaded in tension, the “length” of the adhesive inthe direction of the tensile load can vary from a few thou-sandths to a tenth of an inch. The “cross section” perpendic-ular to the tensile force can be literally thousands of squareinches. Because the adhesive is bonded to the substrates it isnot free to change its cross section by “necking down.” Thus,its ability to elongate is severely restricted and the elongationachieved in the adhesive joint is not the same as in the testspecimen. In fact, at most it can only be a small fraction ofthe elongation measured in ASTM D 638.15

2.3.3 Shear strength—Shear strength is the most importantproperty of adhesive materials commonly used to bondconcrete. Shear strength is usually the only strength propertyfor short-time loads that may be exceeded without thebonded concrete substrate failing first. If the shear forces inthe bond line can be calculated, shear strength data can beused to determine if the adhesive has the strength required.

2.3.4 Flexural strength—As with tensile strength, adhesivematerials have high flexural strength relative to concrete.Flexural strength of an adhesive is seldom a critical factor inadhesive bonding of concrete.

2.3.5 Modulus of elasticity—The stiffness of polymeradhesives varies from rubber-like with some silicones andpolyurethanes to glass-like with some methacrylate andpolyesters (refer to Table 1). However, the modulus of allpolymer adhesives is affected by temperature, especiallynear or above the heat-deflection temperature (HDT). Belowthe HDT, the change in modulus with temperature is modest(Fig. 1).

Although the modulus of elasticity of polymeric adhesivesused with concrete ranges from about 2% to no more than20% of the modulus of elasticity of concrete, this differencehas an insignificant effect on transfer of load because of thevery small volume of adhesive per unit area of bond line.

2.3.6 Heat-deflection temperature (HDT)—Each polymeradhesive formulation has a specific HDT. Frequently, manu-facturers’ literature and technical references report physicalproperties at only one temperature. When this is so, it isimportant to know the HDT to be able to anticipate if thephysical properties at actual service temperatures will be

Table 1—Polymer materials: typical physical properties (from Reference 26)Acrylic Epoxy Polyester Polyurethane Silicone Styrene-butadiene

Tensile strength, psi (ASTM D 638) 5000 to 9000 4000 to 13,000 600 to 13,000 175 to 10,000 350 to 1000 100 to 9350

Tensile elongation, % (ASTM D 638) 20 to 70 3 to 6 2 to 6 100 to 1000 20 to 700 20 to 1350

Compressive strength, psi (ASTM D 695) 4000 to 14,000 15,000 to 25,000 13,000 to 30,000 20,000 NR NR

Compressive modulus at 73 °F, 103 psi(ASTM D 695)

290 to 370 NR 300 to 400 10 to 100 NR 3.6 to 120

Heat deflection temperature, °F (ASTM D 648) 165 to 209 115 to 550 140 to 400 NR NR <0 to 170

Coefficient of thermal expansion, 10–6/in./in./°C(ASTM D 696)

48 to 80 45 to 65 55 to 100 100 to 200 300 to 800 67 to 140

Note: NR: not reported.


substantially different from those strengths reported in thepublished literature. Modulus of elasticity, adhesivestrength, bond strength, creep resistance, and chemical andradiation resistance all begin to change at about 18 °F (10 °C)below the HDT and begin to fall off rapidly in a regionbeginning about 18 °F (10 °C) above the HDT16-18 (also seeFig. 1). Heat-deflection temperature is determined by ASTMD 648.

2.3.7 Creep resistance—Polymer adhesives have a muchhigher tendency to creep than inorganic materials such asconcrete. Sustained loads at temperatures more than 18 °F(10 °C) above the HDT can result in creep to failure.19 Creepresistance can always be improved by reducing bond-linethickness, by increasing filler content of the adhesive assupplied by the manufacturer, or by adding aggregate in thefield. The amount of aggregate that can be added is limitedby the degree that workability is reduced and/or air voidsresult from too high an aggregate-to-adhesive ratio. Physicaltesting is required to quantify the effect of filler addition foreach specific adhesive.

2.3.8 Coefficient of thermal expansion—Polymer adhesiveshave coefficients of thermal expansion two to ten times thatof concrete (refer to Table 1). When the adhesive is confinedin a narrow [1/8 in. (3.2 mm) or less] bond line between twoconcrete elements or between concrete and steel, thisdifference bas not proven to be a problem. However, whenplaced in thicker sections or used to bond materials with agreater thermal expansion and contraction than that ofconcrete, the difference can cause failure in the concrete ifthe bonded elements are subjected to low temperatures(below 30 °F).

Problems caused by the differences in thermal expansionof the adhesive and concrete can always be lessened byreducing bond-line thickness. Choosing an adhesive with alower modulus of elasticity also helps to minimize stresscaused by differences in thermal expansion but increases thedanger of creep failure if the bond line is subjected tosustained loads.

2.3.9 Fire resistance—Polymers are combustible, as aremost organic materials. Incorporation of special fire-retardantadditives and inorganic fillers allows the formulation ofadhesives with fire resistance acceptable for some applications.The performance of a bonded concrete structure or of anassembly of concrete adhesively bonded to other materialswill depend on the insulation value and thermal conductivityof each of the bonded materials, as well as the temperaturelevel (see Section 2.3.6), duration of exposure, and themagnitude and direction of stress on the bond line. An analysisshould be performed to estimate the actual temperature thatmay be reached, and consideration should be given to thepossibility that some of the bonded material may beconsumed or removed by the fire. Through appropriate design,including plaster coating of the concrete member to preventburnout of the adhesive, the fire resistance of adhesivelybonded concrete structures can be maintained within desiredlevels. Test data for a specific application and configurationshould be required when a fire rating is required.20,21

2.3.10 Age hardening—Most polymer adhesives developover 90% of their strength at normal ambient temperature, 68to 100 °F (20 to 38 °C), within 7 days after placement.However, curing continues and results in higher strengthaccompanied by higher modulus, or by hardening.22 Agehardening is undesirable with flexible, low-modulus adhesivesthat are expected to maintain their flexibility over a longperiod of time. Adhesives are available for which long-termtest data are available. Accelerated aging data using elevatedtemperature aging for several days is often used as anindication of susceptibility to aging. However, a precisecorrelation between long-term tests at the expected servicetemperature and accelerated tests can be established only byconducting both tests.

2.3.11 Chemical resistance—The degree of chemicalresistance varies greatly, not only between polymer groups,but also from formulation to formulation within a polymergroup; refer to Table 2 for comparison of the polymergroups. Chemical resistance of an adhesive in a bond line isoften better than chemical resistance tables would indicatebecause only a very small surface area (the edges of the bondline) of the entire mass of adhesive is exposed to thechemical environment.

2.3.12 Water resistance—Cured polymer adhesives havegenerally good water resistance. As with chemical resistance,there can be a wide variation both between polymer groupsand within a polymer group for resistance to water. Relativewater resistance can be measured by water absorption testssuch as ASTM D 570. However, water resistance in servicealso depends on the degree of exposure of the adhesive towater, either through the substrates or at the edge of the bondline (Table 2 gives a comparison of polymer groups).

2.3.13 Radiation resistance—Polymer materials are muchmore susceptible to radiation than inorganic materials suchas concrete. Within a polymer type formulation, variationscan greatly influence radiation resistance. Refer to Fig. 2 forrelative radiation resistance for polymer type groups.23-26

Fig. 1—Modulus of amine-cured epoxy (from Reference 38).


2.4—Distinguishing characteristics2.4.1 Epoxy adhesives—Epoxy adhesives are generally

composed of an epoxy resin, an amine or polyamid curingagent, reactive diluents, and, in some cases, inorganic fillersand thixotroping agents. They are the most commonly usedpolymeric adhesives.

Epoxy adhesives generally have excellent adhesionbecause of relatively low curing shrinkage, with low surfacetension and molecular properties that enhance their attraction toa wide variety of substrates. They are very tolerant of thealkalinity of concrete.

Epoxy adhesives can be formulated to cure at temperaturesas low as 0 °F (–18 °C) or to have a working life allowing useat 100 °F (38 °C).

Most epoxy adhesives have very low ratios of resin tocuring agent, which allows proper metering and mixingwithin the tolerances of available automatic equipment.

Epoxy adhesives conforming to ASTM C 881 will bond toconcrete substrates and some will cure and bond under-water.27 Since resin systems (resin/curing agent) are availablewith viscosities lower than 100 cps and are in semi-solidform, they can be formulated into adhesive products thatpour and penetrate but require containment in a bond line orinto products that can fill gaps without being contained.

Epoxies can be formulated with HDTs as low as 10 °F(–12 °C) or as high as 180 °F (82 °C) after curing at normalambient temperatures. This means that they can be tailoredto a wide variety of strength and modulus requirements for abroad range of service temperatures.

Water and chemical resistance of epoxy adhesives aftercure, as a class, is second only to polyester adhesives.

2.4.2 Polymer adhesives—Unsaturated polyester resinsare generally dissolved in styrene monomer. They are cured

Table 2—Chemical and water resistance: polymer materials*Acrylic Epoxy Polyester Polyurethane Silicone Styrene-butadiene

25 °C 65 °C 25 °C 65 °C 25 °C 65 °C 25 °C 65 °C 25 °C 65 °C 25 °C 65 °C

Nonoxidizing acids S Q S S Q Q Q U Q Q S S

Oxidizing acids U U U U U U U U U U U U

Aqueous salt solution S S S S S S S S S S S S

Aqueous alkalies S Q S S U U Q U S Q S S

Polar solvents S Q S S Q U U U S S S S

Nonpolar solvents U U S Q U U Q U Q U U U

Water S S S S S Q S S S S S S*Source: Reference 37.Notes: S = satisfactory; Q = questionable; U = unsatisfactory.

Fig. 2—Radiation resistance of polymer materials (from Reference 23).


with initiators, usually an organic peroxide such as methylethyl ketone peroxide or benzoyl peroxide.

Typically, promoters or accelerators are used to activatethe decomposition of the initiator at room temperature, thusenabling rapid low-temperature curing.

Because of their relatively high shrinkage while curing,polyesters have found only limited use as adhesives.28 Epoxyor modified-urethane primers may be used to improve theoverall bond strengths to concrete substrates if the primersare compatible with the polyester resin prior to use. Resis-tance to bond failure can also be increased by increasingthe flexibility of the polyesters, thus providing some localstress relief during the application of external forces. Mostpolyesters do not bond well to damp or wet substrates andshould not be used when these conditions exist.28 However,recent research has shown that some vinyl esters, a typeof polyester, can bond under such conditions.

Curing of polyesters can be accelerated by the addition ofan accelerator component, which can provide full cure inapproximately 2 minutes. The use of accelerators thatprovide very short cure times requires mixing with automaticequipment. The accelerator is usually added at a very highratio of resin/accelerator (100/1 to 100/10). Since the accel-erator does not become an integral part of the polymersystem, intimate mixing with the monomer resin at a preciseproportion is not required to achieve full cure.

Generally, polyesters have excellent resistance to acidenvironments. Some polyesters have relatively poor resistanceto alkalis and solvents. Although water resistance of thepolymer itself is good, most polyester adhesive bonds toconcrete deteriorate under constant wet conditions.

Polyesters, in general, are considered flammable, withflash points below 100 °F (38 °C). However, products withflash points over 100 °F (38 °C) are available. The peroxidesused as initiators, when in the pure state, may decomposerapidly at elevated temperatures over 90 °F (32 °C) and mayeven cause fire or explosion. Powder peroxides, such asbenzoyl peroxide, are extended with inert fillers or aresupplied as emulsions, or in paste form in combination withwater or inert organic liquids, thus minimizing the explosionhazard. In any event, prolonged storage of the initiators atelevated temperatures should be avoided to avoid decompo-sition of the peroxide.

2.4.3 Acrylic adhesives—Methyl methacrylate and high-molecular-weight methacrylate monomers of the acrylic familyare used as solvent-free adhesives for concrete. Theseadhesives generally share the same characteristics as poly-ester adhesives. They are most commonly used by mixingwith fine aggregate to form an easily flowable adhesive mortar.

The flowability of the mortar can be controlled by theamount of aggregate added. The mortar can be used as anadhesive to fill wide bond lines and provide a cure adequatefor service in 30 minutes to 2 hours. In almost all cases, a primercomposed of the methacrylate monomer cured with an organicperoxide is used to provide an improved bond to concrete.

2.4.4 Polysulfide adhesives—Polysulfides are mostfrequently used as flexibilizers in epoxy resin formulations.These formulations are sometimes referred to as “polysulfide

adhesives,” but they fit properly into the “epoxy adhesive”category. Polysulfide materials that are primarily jointsealants can be used to bond glass to concrete.29

2.4.5 Polyurethane adhesives—Polyurethane adhesivesare available as both rigid and flexible materials. Whencombined with an aromatic amine, the urethane forms a rigidpolymer similar to epoxy adhesives. When combined with apolyol, they form an elastomer. They have limited use withconcrete because of their low bond strength. The flexibletypes have been used in membrane systems and for bondingceramic tile to concrete where impact resistance is required.

2.4.6 Silicone adhesives—Silicones that have the ability tocure in a wide temperature range are almost exclusively usedas flexible joint sealants.29 However, they can be used tobond elements such as windows to concrete where a highlyflexible adhesive is required to minimize concentration ofstresses. Silicone should not be used in applicationsrequiring resistance to sustained loads.

CHAPTER 3—WATER-BORNE ADHESIVES(LATEX AND LATEX-POWDER ADHESIVES)

The only water-borne adhesives currently used to bondconcrete are latex and latex-powder adhesives. There are twotypes of latex and latex-powder adhesives:30 Type I, whichis designed to be used without further formulation, and Type II,which is designed to be used in slurry form with a hydrauliccement, usually portland cement. For Type II adhesives, theratio of latex to cement is about one part latex solids to fourparts of cement by weight.

Both types of adhesives are generally used for bondingfresh, unhardened concrete to hardened concrete. However,Type II adhesives have occasionally been used for bondinghardened concrete to hardened concrete. Latexes and latexpowders are generally made by emulsion polymerizationtechniques, which have been described in the literature.31

The types in use today include the following:• Polyvinyl acetate (PVA)• Vinyl acetate copolymers (VAC)• Polyacrytic esters (PAE)• Styrene-butadiene copolymers (SB)

Type I latex and latex-powder adhesives are generallymade using a polyvinyl alcohol (PVOH) surfactant system.This type of adhesive gives a dried film that is redispersibleupon application of water. This category includes most poly-vinyl acetate and vinyl acetate copolymers. The morecommon comonomers are ethylene, butyl acrylate, and thevinyl ester of versatic acid.

Type II latex adhesives are usually made with non-ionicsurfactant systems such as alkyl phenols reacted with variouslevels of ethylene oxide. Often, low levels of anionicsurfactants are incorporated to assist in polymerization or toresult in specific latex properties. This type of latex gives adried film that is not redispersible. Polyacrylic esters andstyrene-butadiene copolymers are included in this category.

3.1—Application characteristics3.1.1 Surface preparation—For both Type I and II adhesives,

the surface should be damp, but without any standing water.


This damp condition is conducive to penetration by thepolymer particles of the adhesives into the hardened concrete.

3.1.2 Working life—Type I latex adhesives have a virtuallyunlimited working life because of their redispersible charac-teristic. The adhesive is usually applied by brush or roller,and the fresh, unhardened concrete can be applied whetherthe latex is still wet or has dried. In the latter occurrence,water from the fresh, unhardened concrete causes redispersionof the latex polymer. Although it is recommended that thefresh, unhardened concrete be placed within 24 hours ofapplying the latex, satisfactory bonds have been obtainedwhen the fresh, unhardened concrete was placed up to 7 daysafter latex application. Note that the dried film of the Type Ilatex adhesive must be kept clean from dust and othercontaminants between the times of film forming and theapplication of the fresh concrete.

Type II adhesives have a limited working life, the lengthof which will depend on the type of latex, the type of hydrauliccement, and the environmental conditions. Typically, theworking life of the slurry, in a relatively closed container,will be from one to several hours; however, in an open environ-ment, drying can occur quickly and shorten working life toless than 30 minutes. It is important that the fresh concrete beplaced while the latex-cement slurry is still wet. If the slurryhas dried, it may act as a bond breaker rather than an adhesive.

3.1.3 Curing—Curing of Type I adhesives depends on thecure of the fresh concrete because Type I adhesives cure bydrying. The drying occurs as water is removed either byevaporation or by hydration of the cement in the fresh concrete.

Curing of Type II adhesives depends on the rate of hydrationof the cement in the slurry and also on evaporation of the water.

3.1.4 Methods of application—Type I and Type II adhesivesare usually applied by brush or roller, although other techniquessuch as spraying and troweling have also been used. It isessential that the surface being coated be thoroughly damp,and that the application technique be such that the adhesivecompletely “wets” the surface.

3.1.5 Application conditions—It is essential that the latexadhesive, whether Type I or II, coalesces to form a polymerfilm. Consequently, application temperatures must either beabove the minimum film-forming temperature (MFFT) orabove 50 °F (10 °C), whichever is higher, when the adhesiveand the fresh concrete are placed.

Although the surface must be thoroughly damp when thelatex adhesive is applied, the adhesive and fresh concreteshould not be placed during wet environmental conditions,such as in rain or snow.

3.2—Properties of cured adhesive3.2.1 Bond strength—The bond strength of Type I and

Type II latex adhesives will depend on the latex, the type ofcement, the quality of the hardened surface, and the qualityof the fresh concrete. When tested by ASTM C 1042 method,Type I adhesives usually give bond strengths in excess of300 psi (2.1 MPa), while Type II adhesives give strengthsusually in excess of 1200 psi (8.3 MPa).32

3.2.2 Shrinkage—There is virtually no shrinkage associatedwith Type I and Type II latex adhesives because these

materials, when properly applied, completely migrate into thehardened surface and the fresh concrete. Consequently, anyshrinkage that occurs is caused by shrinkage of the freshconcrete.

3.2.3 Water resistance—The water resistance of Type Ilatex adhesives has always been considered suspect becausethe latex film is redispersible and vinyl acetate hydrolyzes inthe presence of moisture and high pH values to give water-soluble products (vinyl alcohol and a metallic acetate).However, this type of adhesive has been successfully usedwithout apparent problems in areas exposed to moisture. It ispostulated that the function of the adhesive is to insure thatthe fresh concrete “wets out” the hardened concrete surface.The resulting bond is obtained from the penetration of thecement paste of the fresh concrete into the surface. If thispostulation is correct, it explains why moisture failures ofType I adhesives have not occurred where expected.

Type II latex adhesives (slurries of latex and hydrauliccement) have excellent water resistance. In fact, such slurriesare used for waterproofing swimming pools and for corrosionprotection of steel members.33

3.3—Distinguishing characteristics3.3.1 Polyvinyl acetate—Polyvinyl acetate latexes are

Type I adhesives and are usually formulated with a plasticizersuch as dibutyl phthalate or dipropyl glycol dibenzoate. Theplasticizers are added to decrease the minimum film-formingtemperature (MFFT). This type of adhesive is usually madein a polyvinyl alcohol surfactant system and is available bothin the latex form and as a redispersible powder. Water resis-tance of such adhesives is suspect because of hydrolysis ofthe polyvinyl acetate. Films of the latex are redispersible.

3.3.2 Vinyl acetate copolymers—Copolymers of vinylacetate with such materials as butyl acrylate, ethylene, and thevinyl ester of versatic acid are Type I adhesives but can alsobe used as Type II adhesives. They are generally made in poly-vinyl alcohol surfactant systems and are available in latex andredispersible powder forms. Their water resistance is muchbetter than that of polyvinyl acetate, both because thecomonomer reduces the hydrolysis of the vinyl acetategrouping, and because the resultant product is not as watersoluble as polyvinyl alcohol. The water resistance of suchpolymers will depend on the type and ratio of comonomer tovinyl acetate. The comonomer also causes a reduction in theminimum film-forming temperature, which eliminates theneed for the addition of plasticizers. When used as Type IIadhesives, bond strengths (ASTM C 1042) usually exceed1000 psi (6.9 MPa). This value is slightly lower than mostother Type II latex adhesives. It has been postulated32 thatthese lower values may be caused by the larger particle size ofsuch latexes.

3.3.3 Polyacrylic esters and acrylic copolymers—Poly-acrylic ester latexes, such as polyethyl acrylate, and acryliccopolymer latexes, are Type II latex adhesives. They aregenerally made using primarily a nonionic surfactant system.They could be used as Type I adhesives, but this is notrecommended because the dried films are usually notredispersible. If the latex dries before placement of the fresh


concrete, the dried film can act as a bond breaker rather thanas an adhesive. Glass transition temperatures for such latexesare normally less than 18 °F (10 °C). Low levels (less than2%) of reactive groups, such as vinyl carboxylic acids, maybe incorporated in the polymerization of these polymerlatexes. These groups can improve adhesion by ionic reactionwith metallic radicals in the surface of the fresh concrete.However, it has been observed that such groups may retardthe initial hydration of the hydraulic cement.

3.3.4 Styrene-butadiene copolymers—Styrene-butadienecopolymer latexes are Type II adhesives. They could be usedas Type I adhesives but are not recommended for this categorybecause their films are not redispersible. In addition, theirsurfactant system is primarily of the nonionic type. Smalllevels of reactive groups, such as vinyl carboxylic acids, canbe incorporated in the polymerization. Such groups canimprove adhesion and latex stability, but may also retard theinitial hydration of the hydraulic cement.

CHAPTER 4—ADHESIVE SELECTION CRITERIAThis chapter describes the factors that can be important in

choosing an adhesive for a specific application.

4.1—Type and magnitude of loadsFor permanent adhesive bonds, the adhesive should be

able to transfer loads to the same degree as the structuralelements that are bonded together. For each load, a determi-nation should be made of:• Direction (tension, compression, shear, flexure)• Rate (static, dynamic)• Duration• Frequency

Most often data are available only for a single load ratewhile information on creep, fatigue, or dynamic loading isnot available. For very critical adhesive applications, ifadequate test data are not available, a test program should beconducted that simulates the load conditions expected.Alternately, field experience of an adhesive under similarservice and environmental conditions can indicate thesuitability of a polymer adhesive for a particular use.

4.2—Conditions during applicationEqually as important as the strength characteristics of the

adhesive is whether it can be installed to provide thestrengths that are achieved in controlled laboratory tests.Factors that affect the installation and that the adhesive mustbe able to tolerate are described in the following sections.

4.2.1 Surface contamination—The presence of oils,greases, chemicals, dirt, dust, or any other foreign materialscan interfere with achieving a good bond. If a foreignsubstance cannot be completely removed, the adhesivechosen must be able to tolerate its presence. This tolerancecan be demonstrated only by testing under the specific appli-cations and service conditions expected.13,14

4.2.2 Temperature of the contact surfaces—The temperatureof the contact surfaces and of the adhesive, when it is appliedduring the curing period of the adhesive, will affect the rateof bond strength development. Low temperatures may make

the adhesive too viscous to apply properly. High temperaturesmay cause the adhesive to gel before it can be properlyplaced and the substrates joined.

4.2.3 Wetness of the substrates—The presence of watercan seriously affect the ability of adhesives to bond toconcrete or other construction materials. If there is anychance that the surfaces to be bonded together will be damp,have residual water on them, or be submerged, the adhesivespecified must be compatible with moisture to achieve therequired bond strength.

4.2.4 Surface accessibility—The accessibility of thesurfaces to be bonded may dictate an adhesive with a longworking time. The length of time that external supports forbonded elements may be in place during the curing of theadhesive can also influence the selection of the adhesive.

CHAPTER 5—ADHESIVES FORBONDING OF HARDENED CONCRETE

TO HARDENED CONCRETEPolymer adhesives are frequently used in segmental

construction to bond together broken concrete, and to attachelements such as facades to concrete structures. In most criticalsituations, the adhesive bond is used in conjunction withmechanical attachments, with reinforcing steel, or withtendons that cross the bond line.

5.1—Important application characteristics5.1.1 Viscosity and thixotropy—An adhesive for bonding

hardened concrete to hardened concrete must be viscous andthixotropic enough not to run out of the bond line prior toforming a gel. It must also be applied in a thickness that willcompletely fill any irregularities that exist between thesurfaces to be bonded. Except for match cast segments, thebond line between concrete elements is seldom uniform.

5.1.2 Working life—The working life should be adequateto allow placing, positioning, and aligning the concreteelements to be bonded. In bonding large segments, especiallywhere several segments are assembled at one time, a workinglife of many hours is necessary. Once the working life hasexpired but before cure has taken place, the concrete elementscannot be realigned or adjusted without significantly reducingthe bond strength that would be realized on full cure.

5.1.3 Cure time—When choosing an adhesive for itscuring time, the working life requirements described inSection 5.1.2 must be considered since cure time andworking life for polymer adhesives are related.

5.1.4 Bond-line thickness—Recommended bond-linethickness requirements vary from one adhesive to another. Ingeneral, however, the strength of unreinforced jointsdecreases as the bond line thickness increases.

5.2—Important bond-strength considerationsAlthough the published bond strengths for polymer

adhesives may appear to be adequate for a specific hardenedconcrete to hardened concrete application, the effects of highambient temperatures (Sections 2.3.6 and 2.3.7) must beconsidered, especially if reinforcement does not passthrough the adhesive joint.


CHAPTER 6—ADHESIVES FOR BONDING PLASTIC CONCRETE TO HARDENED CONCRETE

Polymer adhesives provide a better bond of plasticconcrete to hardened concrete than can be obtained byrelying on the cement itself or on a cement slurry, becausepolymer adhesives shrink less than cement paste uponcuring, and because they tolerate a wider range of moistureconditions in the plastic concrete and the hardened substrate.

The primary use of all types of water-borne adhesives withconcrete is to bond plastic concrete to hardened concrete.The only solvent-free adhesives used for bonding plasticconcrete to hardened concrete are epoxy adhesives because,unlike other solvent-free adhesives, they can be readilyformulated to cure and bond in the presence of water.

6.1—Important application considerations6.1.1 Viscosity and thixotropy—Most applications of

bonding fresh concrete to existing concrete are on relativelylarge areas.

To place the adhesive economically, it is desirable to usean adhesive that is sufficiently low in viscosity to be sprayedor applied by a roller or squeegee. However, if the surface isrough, as it would be from only rough trowelling or chipping,the adhesive must have enough thixotropy to maintain auniform bond-line thickness without draining away from thehigh spots and into the low spots. For vertical surfaces, theadhesive must be able to stand without running off.

6.1.2 Working life—The working life of an adhesive usedfor bonding fresh concrete must be long enough to allowworkers time to place the concrete before the adhesive gels.This is especially important in large concrete placements, orwhen the adhesively bonded concrete must be placed in forms.

6.1.3 Cure time—With solvent-free adhesives, there mustbe a proper balance between adhesive curing time andconcrete curing time. If the adhesive cures before theshrinkage in the curing concrete takes place, the concrete atthe interface can be weakened enough to result in immediatebond failure, even without external loads. If the adhesivecures too slowly, it may not have the strength in its uncuredstate to resist curling caused by curing shrinkage of large thinsection concrete placements that are unrestrained. A modifiedASTM Test Method C 882 can provide assurance that theproper balance of cure rates exist. It is vital, of course, thatthe specific adhesive and concrete mixture to be used in thefield application rather than the mortar mix specified for usein ASTM C 882 be used in the laboratory tests. Additionally,the 3 x 6 in. cylinder size specified in ASTM C 882 may haveto be increased to provide a cylinder diameter to largeaggregate ratio greater than three to one as prescribed inASTM C 192. For general construction, epoxy adhesivesconforming to ASTM C 881 have been found to be adequate.

6.1.4 Bond-line thickness—There are wide variations inthe recommendation of manufacturers regarding applicationrate which in turn determines bond-line thickness. Roughsurfaces actually have greater true surface areas than smoothsurfaces of the same dimensions. For epoxy adhesives,application rates should be between 25 and 100 ft2/gal. (0.61and 2.45 m2/L), depending upon the surface profile. The

maximum bond-line thickness for water-borne adhesives islimited by their viscosity.

6.1.5 Water sensitivity—By the very nature of the processof bonding fresh concrete, the adhesive must tolerate waterprior to cure of the adhesive. There are wide variations in thesensitivity to water from one adhesive to another, evenamong those used to bond fresh concrete. There are alsogreat differences in the amount of water present in differentconcrete mixtures. The only way to be absolutely sure ofbond strength capability is to conduct one test, such as amodified ASTM C 882, using the specific adhesive andconcrete mixture (see Section 6.1.3). For general constructionapplications, materials conforming to ASTM C 881 orASTM C 1059 have proven to be satisfactory.

6.2—Important bond-strength considerationsEpoxy adhesives provide higher bond strengths than

water-borne adhesives. In thicker bond lines, epoxy adhesives,as opposed to water-borne adhesives, can bond to a greatersurface area of the larger aggregate. As an example, ASTMC 881 requires a minimum slant-shear strength of 1500 psi(10.3 MPa) for an epoxy adhesive, whereas ASTM C 1059requires a minimum of 400 psi (2.8 MPa) for Type I and1250 psi (8.6 MPa) for Type II water-borne adhesives.

CHAPTER 7—ADHESIVES FOR REPAIROF CRACKS IN CONCRETE

Epoxy adhesives are the most common adhesives used forcrack repair. They are usually introduced into cracks byinjection. High-molecular-weight methacrylates are alsoused on some flat-surface applications by flooding thesurface with adhesive, and they have been used occasionallyto inject into fine cracks because of their low viscosity.Polyesters and latex-cement slurries have been used veryinfrequently with either application method.18,21

7.1—Important application considerations7.1.1 Viscosity and thixotropy—Low viscosity is required

for adhesives to penetrate cracks without using high injectionpressure. Typical viscosities for liquid epoxy injectionadhesives range from 100 to 500 cps at 77 °F (25 °C). High-molecular-weight methacrylates have viscosities in the rangeof 15 to 20 cps at 77 °F (25 °C). However, if injection adhesiveswith viscosities lower than 100 cps are used, the adhesive canpenetrate into the concrete so far that it leaves a starved bondline. In this case, there must be a continual reservoir ofadhesive available to the crack until the adhesive gels to fillthe bond line. Liquid adhesives without thixotropic propertieswill also drain out of a crack, even into subgrades, if all facesof the crack are not sealed prior to filling the crack. Forcracks where all faces cannot be sealed, a thixotropic orpsuedoplastic adhesive should be used which will stay in thecrack without constraint.

7.1.2 Water sensitivity during cure—All cracks in concretethat is outdoors should be assumed to have water in themunless there is evidence to the contrary. An adhesive that willbond in the presence of water should be used whenever wateris present in the crack.


Conformance with ASTM C 881 Type IV or ASTM C 1059will assure that a satisfactory adhesive is chosen. For adhesiveinjection into cracks underwater, no standard tests exist. Speciallaboratory or field tests should be conducted to qualify anadhesive for underwater injection. ASTM C 882 has been usedfor this purpose by fabricating the test specimens underwater.

7.1.3 Concrete temperature—Cracks in concrete open andclose as the temperature of the concrete changes. If a crackcannot be injected while it is in its widest position, an injectionadhesive should be chosen that cures fast enough to resist thetensile forces that result when the crack widens fromtemperature change.

7.2—Important strength considerations7.2.1 Limitations—Adhesive bonding of cracked concrete

may not be permanent if the original cause of the crack is noteliminated. For example, if overloads continue to exist or iffoundations continue to settle, the concrete structure willprobably crack again in the vicinity of the original crack.Factors such as these should be considered before repairingthe original cracks.

7.2.2 Flexibility—The use of a low-modulus flexibleadhesive in a crack will not allow any significant movementof the concrete structure for the reasons cited in Section 2.3.2.The effective modulus of elasticity of a flexible adhesive in acrack is substantially the same as that of a rigid adhesive.15

7.2.3 Creep resistance—Frequently the adhesive in abonded crack will be subjected to sustained loads. Theseloads may be external or they may be caused by restraints ona structure that is undergoing cyclic temperature changes.Unless it can be determined that the adhesive in a crack willnot be subject to sustained loads, an adhesive conforming toASTM C 881 Type IV should be used.

CHAPTER 8—ADHESIVES FORBONDING INSERTS INTO CONCRETE

Solvent-free polymer adhesives have been widely used tobond or grout anchorages and reinforcing steel into concrete.This procedure avoids the difficulties of maintaining thelocation of an insert during a concrete placement, and allowsplacement when the location has not been decided prior tothe concrete setting of the concrete.

Glass capsules containing both the resin and the initiatoror curing agent have been widely used to bond anchors inconcrete. The two components are separated in the capsuleas supplied by the manufacturer. The capsule is placed in thehole in the concrete; as the anchor is inserted and twisted, thecapsule breaks and the adhesive is mixed.

8.1—Important application considerations8.1.1 Viscosity and thixotropy—For vertical holes with the

opening upward, a liquid adhesive can be used. A liquidadhesive requires less time to place than a paste or thixo-tropic or psuedoplastic adhesive, and it is much less likely totrap air in the bond line. For vertical overhead and horizontalholes, a thixotropic or psuedoplastic paste adhesive is moresuitable because it will not require containment to keep itfrom running out of the hole. However, it must be capable of

being pumped from the bottom (back) of the hole toward thefront of the hole to avoid trapping air bubbles in the bondline. Air bubbles would reduce contact area and result in aweakened bond.

8.1.2 Hole diameter—Hole diameters normally used are1/8 to 1/2 in. (3.2 to 12.7 mm) greater than the bolt, dowel,or insert diameter. In all cases, the smaller the annulusbetween the insert diameter and the hole diameter, the lowerthe possibility of creep failure. As the annulus dimensionincreases, the potential for creep failure under constant loadincreases. (Refer to Section 2.3.7.)

8.1.3 Hole depth and spacing—To develop the fullstrength of a steel anchor or a reinforcing bar, as opposed toinducing a failure in the concrete, the steel should generallybe embedded to a minimum depth of ten times its diameter.

Anchor spacing should allow a sufficient quantity ofanchors to transfer the desired loads from the attachedmembers without development of excessive stress interactionthrough the concrete between the anchors. For specific guide-lines for hole depth and spacing for steel anchorages, see ACI349, “Code Requirements for Nuclear Safety RelatedConcrete Structures,” Appendix B, Steel Embedments.30,34

8.2—Important strength considerations8.2.1 Pullout strength—Pullout strength is generally deter-

mined by applying an axial tensile load to the anchorageuntil tensile failure occurs. The ability of the concrete-anchor system to develop full pullout strength of the anchoras determined by ASTM E 488 depends mostly on the bondstrength of the adhesive and the cleanliness of the hole. Thistest evaluates the ability of the adhesive to bond and cureunder the conditions of moisture and surface preparationactually encountered in application.

8.2.2 Creep resistance—Many inserts that are bonded intoconcrete are put under a constant load. Examples are fixturesbeing hung from anchorages and torqued anchor bolts.Therefore, creep resistance should be carefully considered(see Section 2.3.7). For critical applications, pre-testing of amockup is recommended because no standard test methodsare currently available.

CHAPTER 9—ADHESIVES FOR BONDING CONCRETE AND OTHER MATERIALS

Epoxy and some polyester adhesives are commonly usedfor bonding steel in the form of inserts (see Section 8),external28,29,35 or internal36 reinforcement, and protectionplates. For other construction materials such as aluminum,wood, glass, rubber, and plastics, a wider variety of adhesivesis required because of the very different characteristics ofeach of these materials.

9.1—Important application considerationsThere are innumerable combinations of types of adhesive

and types of construction materials that can be bonded toconcrete. Which application conditions are importantdepends on which combination is used. Since each applicationis unique, there is little information available except in themanufacturer’s literature. Standard test methods do not exist.


For critical applications, special tests must be designedunless field experience for the exact combination of adhesiveand material to be bonded to concrete can be demonstratedfor the same service conditions. Some of the more commonfactors to consider are listed in the following paragraphs forthe general classes of construction materials.

9.1.1 Steel—If it is necessary to hold a steel plate in placewhile the adhesive cures, care must be taken not to stress thesteel with the application of clamps that will be removedonce the adhesive cures. Because of the much highermodulus of elasticity of the steel compared to the polymeradhesive, the steel can exert stresses on the bond line thatexceed the strength of the adhesive. Even if the adhesivedoes not fail immediately upon removal of the clamps,constant stresses will be built into the bond line, which cancause creep failure at a later time.

Because of its high heat capacity, changes in steeltemperature can lag behind changes in atmospheric temperatureand cause condensation of water vapor on the surface of thesteel. Particular attention should be paid to providing a drysurface. If a dry surface cannot be assured, an adhesiveshould be chosen that will bond to wet steel.

Steel that is exposed to the sun may reach temperatures ashigh as 170 °F (77 °C). The working life of an adhesiveapplied to a steel surface may be much shorter than would beexpected if the ambient temperature or the adhesive temper-ature in the mixing container is used to predict working life.

9.1.2 Wood—The wide variety of chemical, density, andgrain characteristics of the many woods used in constructionmakes it impossible to generalize on the suitability of a typeof polymer adhesive for bonding wood. The particular adhesiveand wood combination should be tested at the wood moisturecontent that is expected when the adhesive is applied.Changes in moisture content that cause the wood to shrink orswell after the adhesive has cured will stress the bond lineand can cause failure of the wood fibers.

Standard laboratory tests are not available either forbonding wood to concrete or for the effect of changes in themoisture content of wood.

9.1.3 Glass—The brittle nature of glass requires that anadhesive be used that will minimize stresses at the bond linecaused by temperature changes or external forces. For thisreason, only silicone and polysulfide materials are usuallyused for bonding glass to concrete.

Particular attention should be paid to the surface conditionof the glass, because any film of oil or other foreignsubstance that may not be visible can interfere with the bond.

9.1.4 Plastics, reinforced plastics, and rubber—There iswide variation in chemical and physical properties amongthe different rubber and plastic materials. Because thesurface energy of most rubber and plastics is much lowerthan that of steel or concrete, they are much more difficult tobond with polymer adhesives. In many cases, the surfacemust be oxidized or otherwise chemically treated to providea bondable surface. In the bond of a flexible plastic or rubberto concrete, the adhesive can be subjected to peel forceswhen the plastic or rubber substrate is loaded in a mannerthat tends to deform the substrate at the bond line. For thisreason, only silicone, polyurethane, and very low-modulusepoxy adhesives are usually used to bond flexible plastics orrubber to concrete.

Some rubber and plastic materials contain nonreactiveplasticizers used to enhance their physical properties. Thepresence of the plasticizer on the surface can prevent a goodbond from being achieved. Migration of the plasticizer to thebond line after the adhesive is cured and bonded can causedeterioration of the adhesive bond.

9.1.5 Aluminum—Because of the rapid formation of oxideon a freshly abraded aluminum surface, aluminum is usuallyprepared for adhesive bonding by treatment with a chromic-sulfuric acid mixture or by anodizing if a long lasting corrosion-resistant bond is desired. In either case, an adhesive primeris used if maximum corrosion resistance is required.


Conditions for use of adhesives

Performance requirements of adhesives

Bond strength (ASTM C 882) Water resistance Temperature resistance

Above 2000 psi(13.8 MPa)

Below 2000 psi(13.8 MPa) Moisture Submerged Below 32 °F (0 °C) Above 120 °F (49 °C)

Plastic concrete to cured concrete E E, SB, PVA, PAE, VAC E, PAE, SB, VAE E E, A, SB, PA E, A, SB, PA

Cured concrete to cured concrete E, P, M E, P, M, PP, S E, P, M, PP E, P, M, PP E, P, M, PP, S E

Cracked concrete E, P, M E, P, M, SB, PAE E, P, M E, P, M E, P, M E

Cured concrete to other materials with similar CTE and EM E, P, M E, P, M, PP, S E, P, M E, M E, P, M E, P, M

Cured concrete to other materials with dissimilar CTE and EM E, PP E, PP, S E, PP E, PP E, PP E, PP

Anchoring bolts E, P, M E, P, M E, P, M E, P, M E, P, M E, P, M

CHAPTER 10—QUICK REFERENCE GUIDE

Conditions for use of adhesives

Application requirements of adhesives

Water resistance Temperature Ability to flow into narrow voidsMoist substrate Submerged substrate Below 32 °F (0 °C) Above 100 °F (38 °C)

Plastic concrete to cured concrete E, PAE, SB, PVA, VAC — — — —

Cured concrete to cured concrete E E E, M E, P, M —

Cracked concrete E, SB, PAE E E, M E, P, M E, P, M

Cured concrete to other materials with similar CTE and EM E E E, M E, P, M —

Cured concrete to other materials with dissimilar CTE and EM E E, PP E, PP E, PP —

Anchoring bolts E E E, M E, P, M E, P, M

ABBREVIATIONS:E: epoxyP: polyesterM: methylmethacrylate monomerPP: polysulfide and polyurethane S: siliconePAE: acrylic latexSB: styrene-butadiene latexPVA: polyvinyl acetate latexCTE: coefficient of thermal expansionEM: elastic modulusVAC: vinyl acetate copolymer latexes

CAUTION:The listing of a particular type of adhesive as suitable for an adhesive require-ment indicates that many adhesive products of that type meet the require-ment. It does not mean that all adhesives of that type meet the application orperformance requirement.

The purpose of the chart is to guide the designer to a generally appropriateadhesive type but the designer must verify that the specified adhesive productmeets the performance and application requirement for each particular project.

CHAPTER 11—REFERENCES11.1—Specified and/or recommended references

The documents of the various standards-producing organi-zations referred to in this document are listed with their serialdesignation, including year of adoption or revision. Thedocuments listed were the latest effort at the time this documentwas revised. Since some of these documents are revisedfrequently, generally in minor detail only, the user of thisdocument should check directly with the sponsoring group ifit is desired to refer to the latest revision.

American Concrete Institute224.1R-84 Causes, Evaluation, and Repair of Cracks in

Concrete Structures503R-80 Use of Epoxy Compounds with Concrete503.1-79(86) Standard Specification for Bonding Hardened

Concrete, Steel, Wood, Brick and OtherMaterials to Hardened Concrete with a Multi-Component Epoxy Adhesive

503.2-79(86) Standard Specification for Bonding PlasticConcrete to Hardened Concrete with a Multi-Component Epoxy Adhesive

ASTMC 192-88 Specification for Making and Curing Concrete

Test SpecimensC 881-87 Specification for Epoxy Resin-Base Bonding

Systems for Concrete C 882-87 Test Method for Bond Strength of Epoxy Resin

Systems Used with ConcreteC 1042-85 Test Method for Bond Strength of Latex

Systems Used with ConcreteC 1059-86 Specification for Latex Agents for Binding

Fresh to Hardened ConcreteD 570-81 Test Method for Water Absorption of PlasticsD 638-89 Test Method for Tensile Properties of PlasticsD 648-82(88)Test Method for Deflection Temperature of

Plastics Under Flexural LoadD 695-89 Test Method for Compressive Properties of

Rigid PlasticsD 696 Standard Test Method for Coefficient of Linear

Thermal Expansion of Plastics Between –30 °Cand 30 °C With a Vitreous Silica Dilatometer

D 907 Standard Terminology of Adhesives


E 488-88 Test Method for Strength of Anchors inConcrete and Masonry Units

The publications may be obtained from the followingorganizations:

American Concrete InstitutePO Box 9094Farmington Hills MI 48333-9094

ASTM International100 Barr Harbor DrWest Conshohocken PA 19428-2959

11.2—Cited references1. Adams, R. D., and Wake, W. C., Structural Adhesive

Joints in Engineering, Elsevier Applied Science Publishers,Essex, 1984, pp. 8-13.

2. Skeist, I., Handbook of Adhesives, 2nd Edition, VanNostrand Reinhold Co., New York, 1977, pp. 3-4.

3. Lee, H., and Neville, K., Handbook of Epoxy Resins,McGraw-Hill Book Co., New York, 1967, pp. 25-7 to 25-11.

4. Skeist, I., Handbook of Adhesives, 2nd Edition, VanNostrand Reinhold Co., New York, 1977, pp. 6-3 to 6-4.

5. Modern Plastics Encyclopedia, McGraw-Hill, NewYork, 1989, pp. 129-132, 134-135.

6. Kinloch, A. J., Structural Adhesives—Developments inResins and Primers, “Curing Properties of ThermosettingPolymers,” by J. K. Gillham, Elsevier Applied SciencesPublishers, London and New York, 1986, pp. 1-6.

7. Rodriguez, F., Principles of Polymer Systems, McGraw-Hill, New York, 1970, pp. 53-55, 62-65.

8. Eirich, F. R., Rheology Theory and Applications,Academic Press, New York and London, 1960, pp. 205-215.

9. Rodriguez, F., Principles of Polymer Systems,McGraw-Hill, New York, 1970, pp. 53-55, 62-65.

10. Skeist, I., Handbook of Adhesives, “Introduction toAdhesives,” Chapter 6, by F. A. Lewis and R. Saxon, 2ndEdition, Van Nostrand Reinhold Co., New York, 1977,pp. 400-403.

11. Lee, H., and Neville, K., Handbook of Epoxy Resins,McGraw-Hill Book Co., New York, 1967, pp. 6-29 to 6-30,21-28 to 21-30.

12. Wake, W. C., Adhesion and the Formulation ofAdhesives, Applied Science Publishers, London and NewYork, 1982, pp. 46, 122-124.

13. Murray, M. A., “Surface Preparation for Adhesives,”Concrete International, V. 11, No. 9, Sept. 1988, p. 69.

14. Gaul, R. W., “Preparing Concrete Surfaces for Coatings,”Concrete International, V. 6, No. 7, July 1984, pp. 17-22.

15. Adams, R. D., and Wake, W. C., Structural AdhesiveJoints in Engineering, Elsevier Applied Science Publishers,Essex, 1984, pp. 121-125.

16. May, C. A., and Tanaka, Y., Epoxy Resins, Chemistryand Technology, Marcel Dekker, Inc., New York, 1973,pp. 400-407.

17. Lee, H., and Neville, K., Handbook of Epoxy Resins,McGraw-Hill Book Co., New York, 1967, pp. 6-25 to 6-27.

18. Gaul, R. W., “State-of-the Art Adhesives for ConcreteConstruction,” Construction Canada, V. 30, No. 3, May1988, pp. 15-20.

19. Adams, R. D., and Wake, W. C., Structural AdhesiveJoints in Engineering, Elsevier Applied Science Publishers,Essex, 1984, pp. 160-162.

20. Plecnik, J. M.; Plecnik, J.; Parra, V.; and Diba, A.,“Fire Testing Epoxies,” Concrete International, V. 8, No. 4,Apr. 1984, p. 29.

21. Plecnik, J. M.; Plecnik, J.; Diba, A.; Howard, J.; andHiremagular, J., “Fire Research on Seismically DamagedConcrete Beams Repaired with Epoxy Adhesives,” FinalReport, Contract No. PFR-7927222, National Science Foun-dation, Washington, DC, Aug. 18, 1983.

22. Struk, L. C. E., Physical Aging in Amorphous Poly-mers and Other Materials, Elsevier Scientific PublishingCo., Amsterdam, 1978, pp. 1-46.

23. Schonbacher, H., “How Plastics Perform UnderNuclear Radiation,” Modern Plastics, Dec. 1985, pp. 64-68.

24. Van de Voorde, M., and Restat, C., Selecting Guide toOrganic Materials for Nuclear Engineering, OrganisationEuropeenne pour la Recherche Nucleaire, Geneva, 1972.

25. “How Radiation Affects Polymers,” Rubber andPlastic Processing, May-June 1963, pp. 23-24.

26. Modern Plastics Encyclopedia 89, McGraw-Hill, NewYork, V. 65, No. 11, Oct. 1988, pp. 576-619.

27. Encyclopedia of Chemical Technology, V. I, JohnWiley & Sons, New York, 1978, p. 503.

28. Mays, O. C., “Structural Applications of Adhesives inCivil Engineering,” Materials Science and Technology, V. 1,Nov. 1985, pp. 937-942.

29. Albrecht, P.; Sahli, A.; Crute, D.; Albrecht, P.; andEvans, B., “Application of Adhesives to Steel Bridges,”FHWA/RD 87/037, Federal Highway Administration, U.S.Dept. of Transportation, Nov. 1984.

30. ASTM C 1059, “Standard Specification for LatexAgents for Bonding Fresh to Hardened Concrete,” ASTMInternational, West Conshohocken, Pa., 1999, 2 pp.

31. Walters, D. G., “What are Latexes?” Concrete Interna-tional, V. 9, No. 12, Dec. 1987, pp. 44-47.

32. Walters, D. G., “Latex Adhesives for BondingConcrete,” paper presented at the American ConcreteInstitute’s Fall Convention, Houston, TX, Nov. 3, 1988.

33. Ohama, Y., “Polymer-Modified Mortars andConcretes,” Concrete Admixtures Handbook, V. S.Ramachandran, ed., Noyes Publications, Chapter 7, 1984.

34. Cannon, R. W.; Godfrey, D. A.; and Moreadith, F. C.,“Guide to the Design of Anchor Bolts and Other SteelEmbedments,” Concrete International, V. 3, No. 7, July1981, pp. 28-41.

35. Jones, R.; Swamy. R. N.; Blorham, J.; and Beuder-balah, A., “Composite Behavior of Concrete Beams withEpoxy Bonded External Reinforcements,” InternationalJournal of Cement Composites, V. 2, No. 2, May 1980.

36. Stratton, W. F., and Crumpton, C. F., “Kansas BridgesRenovated by Post Reinforcement and Thin Bonded


Concrete Overlay,” Concrete Construction, Aug. 1984,pp. 705-709.

37. Seymor, R. B., Plastics Versus Corrosives, John Wiley& Sons, New York, 1982, pp. 147-262.

38. May, C. A., and Tanaka, Y., Epoxy Resins, Chemistryand Technology, Marcel Dekker, Inc., New York, 1973, p. 347.

11.3—Additional referencesCalder, A. J. J., “Exposure Tests on Externally Reinforced

Concrete Beams—First Two Years,” SupplementaryReport 529, Transport and Road Research Laboratory,Crowthorne, 1979.

Cook, J. P., and Panek, J. R., Construction Sealants andAdhesives, 2nd Edition, John Wiley & Sons, New York,1984, pp. 295-297.

Hugenschmidt, F., “Epoxy Adhesives for Concrete andSteel,” Proceedings, First International Congress onPolymer Concretes, London, May 1975.

Luke, P. C. C., “Strength and Behavior of Rebar DowelsEpoxy-Bonded in Hardened Concrete,” thesis, GraduateSchool of Engineering, University of Texas at Austin, 1984.

Plecnik, J. M.; Gaul, R. W.; Pham, M.; Cousins, T.; andHoward, J., “Epoxy Penetration,” Concrete International,V. 8, No. 2, Feb. 1986, pp. 46-50.

Tilmans, A., and Krokosky, E. M., “Effect of Radiation onSome Mechanical Properties of an Epoxy System,” Journal ofMaterials, JMCSA, V. 6, No. 2, June 1971, pp. 465-481.

ACI 503.5R-92 was submitted to letter ballot of the committee and approved inaccordance with ACI standardization procedures.

Documents

503.5R-92