Guide for the Selection of Polymer Adhesives in Concrete (Reapproved 2003)

ACI 503.5R-92 (Reapproved 2003) Guide for the Selection of Polymer Adhesives with Concrete Reported by ACI Committee 503 Raymond J. Schutz Chairman Robert W. Gaul* Subcommittee Chairman Milton D. Anderson* Roger W. Black John P. Cook Floyd E. Dimmick Wolfgang D. Eisenhut Jack J. Fontana* * Myles A. Murray Secretary Joseph A. McElroy* Paul F. McHale Peter Mendis* Richard Montani Joseph M. Plecnik Paul R. Hollenbach David P. Hu T. Michael Jackson Troy D. Madeley Albert Mayer Hamid Saadatmanesh W. Glenn Smoak Joe Solomon Michael M. Sprinkel Douglas G. Walters* Members of Subcommittee who prepared this report. This guide provides the engineer, contractor, and architect with a description of 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 cured concrete, 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 when selecting a structural adhesive, including characteristics during installation and in service. The benefits and limitations of adhesive bonding are discussed for each application. Keywords: acrylic resins; adhesives; bolts; bonding; epoxy resins; fire resistance; 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. CONTENTS Chapter 1—General, p. 503.5R-2 1.1—Organization of the guide 1.2—Caution 1.3—Advantages/disadvantages of adhesive bonding 1.4—Glossary of terms Chapter 2—Solvent-free adhesives, p. 503.5R-4 2.1—Application characteristics 2.2—Properties during cure 2.3—Properties of cured adhesive 2.4—Distinguishing characteristics Chapter 3—Water-borne adhesives (latex and latex powder adhesives), p. 503.5R-8 3.1—Application characteristics 3.2—Properties of cured adhesive 3.3—Distinguishing characteristics Chapter 4—Adhesive selection criteria, p. 503.5R-10 4.1—Type and magnitude of loads 4.2—Conditions during application Copyright © 1992, American Concrete Institute. All rights reserved including rights of reproduction and use in any form or by any means, including the making of copies by any photo process, or by electronic or mechanical device, printed, written, or oral, or recording for sound or visual reproduction or for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyright proprietors. ACI Committee Reports, Guides, Manuals, Standard Practices, and Commentaries are intended for guidance in planning, designing, executing, and inspecting construction. This document is intended for the use of individuals who are competent to evaluate the significance and limitations of its content and recommendations and who will accept responsibility for the application of the material it contains. The American Concrete Institute disclaims any and all responsibility for the stated principles. The Institute shall not be liable for any loss or damage arising therefrom. Reference to this document shall not be made in contract documents. If items found in this document are desired by the Architect/Engineer to be a part of the contract documents, they shall be restated in mandatory language for incorporation by the Architect/Engineer. 865 polyurethane.5R-11 7.3—Advantages/disadvantages of adhesive bonding The major advantage of adhesive bonding is that it allows distribution of an applied load over much larger areas compared to other methods of fastening.5R-14 Chapter 11—References. p. and styrene-butadiene) either as typical values. 1.5R-12 9. . p.1—Important application considerations 8. p.5R-2 ACI COMMITTEE REPORT CONCRETE REPAIR MANUAL Chapter 5—Adhesive for bonding of hardened concrete to hardened concrete.5R-14 11.5R-10 5. the manufacturer’s literature should always be reviewed.5R-12 8. 1.5R-11 6. acrylic. because the adhesive cures for hours or days. in other cases.1—Organization of the guide Sections 2 and 3 of the guide describe the properties of the two major classes of polymer adhesives in use (solvent-free adhesives and water-borne adhesives) and identifies the distinguishing features of the specific polymers (e. as a range of values. epoxy.2—Important strength considerations Chapter 9—Adhesives for bonding concrete and other materials.1—Important application characteristics 6. depending on the cure rate of the adhesive used and the temperature of the elements being bonded. silicones. When using an adhesive.866 503. and bonding inserts into concrete. polyester. acrylic—one of a group of resins formed by polymerizing the esters or amides of acrylic acid. contractor. Sections 5 through 9 provide additional guidance specific to the selection of adhesives for bonding fresh or hardened concrete to hardened concrete. vinyl acetate. Manufacturer’s recommendations should be followed because the adhesive may differ from other adhesives in its class. This guide includes more data and information on epoxy adhesives than on other types because epoxy adhesives are the most versatile and by far the most widely used with concrete. The cited characteristics of classes of polymer adhesives are only a guide to help narrow the field in a search for an appropriate adhesive.1. catalyst—a substance whose presence increases the rate of a chemical reaction. acrylic. 1. 503.2—Important bond-strength considerations Chapter 6—Adhesives for bonding of plastic concrete to hardened concrete.2—Important strength considerations Chapter 8—Adhesives for bonding inserts into concrete. and polyvinyl acetate) within each class. To include all extremes would lead to a less accurate perception of the true nature of these groups of products as they are commonly used. repairing cracked concrete. Because of the ease of tailoring polymer products by formulation. 503. bonding other materials to concrete. p. Section 10 is a quick reference guide to help narrow the search for a proper adhesive. 503. leading to embrittlement. adhesives—the group of materials used to join or bond similar or dissimilar materials. 503. and architect in choosing a proper polymer adhesive for adhesive bonding applications encountered in joining concrete members in construction. It allows attachment without having to alter the shape or deface the elements to be attached. Information on other types is included where there is a choice. age hardening—the progressive change in the chemical and physical properties of an adhesive.2—Cited references 11.1—Important application characteristics 5. 503. for example. the catalyst is consumed and regenerated. In some cases. Many adhesives contain hazardous ingredients. 1. Section 4 lists the basic criteria that should be used in all adhesive selections. Other terms may be found in ASTM D 907. work progress may be slowed down if the other work tasks cannot be scheduled to accommodate the adhesive cure time.1—Important application considerations 7. the catalyst seems not to enter into the reaction.4—Glossary of terms This glossary gives definitions of some terms that are used in adhesive bonding in the concrete industry. 503. The adhesive bond line can also act as a moisture barrier.2 The major disadvantage of adhesive bonding is that the bonded elements cannot be disturbed after being joined. accelerator—a material that increases the rate of a chemical reaction. and rehabilitation of concrete structures. Material Safety Data Sheets (MSDS) and labels should always be consulted before using the adhesive. bond line—the interface between two surfaces bonded together with an adhesive. thus reducing the unit stress on the elements that are bonded. the epoxy resins.g. 503. or as relative values. Thus.2—Caution This guide presents data on the various polymer and copolymer types (epoxy..2—Important bond-strength considerations Chapter 7—Adhesives for repair of cracks in concrete. p. p.3—Additional references CHAPTER 1—GENERAL This guide is intended to aid the engineer. in concrete work. repair.1—Specified and/or recommended references 11. p. but functions by virtue of some other characteristic. some very special products within a group may possess values for a particular characteristic that differ widely from the typical value or fall outside of the range.1—Important application considerations Chapter 10—Quick reference guide. but of high molecular weight. polyvinyl acetate—colorless. minimum film-forming temperature (MFFT)—the lowest temperature at which the polymer particles of a latex have sufficient mobility and flexibility to coalesce into a continuous film. polyurethane—reaction product of an isocyanate with anyone of a wide variety of other compounds containing an active hydrogen group. elastomeric—pertaining to a substance that has rubberlike properties. thixotroping agents—a substance incorporated into an adhesive to impart thixotropy. thixotropy—the property of a material that enables it to stiffen in a short period of time on standing. monomer—an organic liquid. although these two temperatures are not necessarily equal. but to acquire a . or any combination.” thermoplastic—becoming soft when heated and hard when cooled. crosslinking agent. or both. plasticizer—a substance added to polymer or copolymer to reduce its minimum film-forming temperature and/or its glass transition temperature. surface-active agent—a substance that markedly affects the interfacial or surface tension of solutions even when present in very low concentrations. crosslinking agent—a substance that increases the molecular weight of a polymer by chemically linking and bridging the polymer chains. adhesives. polyester—one of a large group of synthetic resins. when added in small quantities. may be used in paints for concrete. heat deflection temperature (HDT)—the temperature at which a plastic material reaches an arbitrary deflection when subjected to an arbitrary load and test condition. more commonly a rubber or resin consisting of large molecules formed by polymerization. a second continuous liquid phase (the external phase). usually accomplished by the action of heat. as well as increase or promote polymerization activity.5R-3 867 with dihydroxy alcohols.SELECTIONOF OFPOLYMER POLYMER ADHESIVES WITH CONCRETE SELECTION ADHESIVES WITH CONCRETE cohesive—the type of molecular attraction that holds adhesives and other materials together. curing agent—a substance that accelerates or participates in the curing of chemicals. abrasionresistant coatings. cure—to change the properties of a chemical (usually a polymer) by increasing its molecular weight by polymerization or crosslinking. used to formulate tough. It can be an indication of the glass transition temperature. substrate—a material upon the surface of which an adhesive is spread for the purpose of bonding. transparency to ultraviolet rays. high dielectric strength. and the like. the higher the softening temperature. glass-like state to an elastomeric-like state. and hardness. glass transition temperature—the temperature or range of temperature at which polymeric materials change from a rigid. of relatively low molecular weight. surface energy—the interfacial free energy per unit area of the boundary between the surface of a substrate and the air above it. one containing two or more hydroxyl groups. increase the activity of catalysts. rather than in the adhesive’s bond to the substrate. with carbon containing side groups. silicones may be used in caulking or coating compounds. initiator—a substance that causes a chemical reaction (such as polymerization or curing) to start.. sometimes referred to as a hardener. rheology—the science dealing with the flow of materials. fiber laminates (mainly glass). mainly produced by reaction of unsaturated dibasic acids 503. emulsion—a two-phase liquid system in which small droplets of one liquid (the internal phase) are immiscible in. surface tension—a measure of surface energy. The term usually applies to free-radical polymerization-type reactions. permanently thermoplastic resin. commonly prepared for application by mixing with a vinyl-group monomer and free-radical catalysts at ambient temperatures and used as binders for resin mortars and concretes. polysulfide—synthetic polymers obtained by the reaction of sodium polysulfide with organic dichlorides. that tend to contain the volume to a minimum surface area. stability toward light. cohesive failure—a failure by separation within the adhesive itself. silicone—a resin in which the main polymer chain consists of alternating silicon and oxygen atoms. admixtures for concrete. that creates a solid polymer by reacting with itself or other compounds of low molecular weight. a substance whose viscosity decreases with increasing shear. gel—a colloid in which the dispersed phase has combined with the continuous phase to produce a viscous jelly-like material. surfactant—a contraction of the term “surface-active agent. usually supplied as an emulsion or water-dispersible powder characterized by flexibility. curing agent. the higher the degree of polymerization. or as adhesives. exothermic—pertaining to a chemical reaction that occurs with the evolution of heat. or within the substrate. with or without pressure. toughness. polyol—a polyhydric alcohol. i. flexibilizer—a substance that is mixed with a more brittle material to make the latter more ductile. and dispersed uniformly throughout. arising from molecular forces at the surface of a liquid. thermosetting—becoming rigid by chemical reaction and not remeltable. epoxy resins—a class of organic chemical bonding systems used in the preparation of special coatings or adhesives for concrete or as binders in epoxy resin mortars and concretes. promoter—substances that. polymer—the product of polymerization. polymerization—the reaction in which two or more molecules of the same substance (monomer) combine to form a compound containing the same elements.e. pseudoplastic—often referred to as thixotropic. catalyst. latex—a dispersion of organic polymer particles in water. copolymerization—polymerization of two or more dissimilar monomers. this condition occurs only in bond lines greater than 1/8 in.10 2.5R-4 ACI COMMITTEE REPORT CONCRETE REPAIR MANUAL lower viscosity on mechanical agitation. The viscosity of any adhesive can be lowered by raising its temperature. the longer the working life. internal stresses are induced in the bond when the adhesive cools to normal temperature. Although special adhesives are available that will cure at temperatures down to 0 °F (–18 °C). and silicones cure by the addition of a catalyst or release of a catalyst included in the formulation. If this happens.1.1. viscosity—the property of a material that resists change in shape or arrangement of its elements during flow. and commonly prepared for application by mixing with a vinyl group monomer and free-radical catalysts at ambient temperatures. This can be achieved either by heating the adhesive itself or by heating the substrate. fillers. Section 2. (6.868 503. 2.1. CHAPTER 2—SOLVENT-FREE ADHESIVES Solvent-free adhesives cure by polymerization of monomeric resins. because in narrow bond lines the heat dissipates into the substrates. vinyl ester—one of a group of synthetic resins produced by the reaction of acrylic with epoxy resin or Bisphenol A. In general. remains sufficiently workable to permit spreading and application.2.2 mm) in thickness. 2.2—Properties during cure 2. an adhesive must be chosen that has been manufactured to include thixotroping agents. Catalytic curing is less temperature-dependent than the monomer/curing agent reaction.3 The temperatures of the adhesive components.5 The curing reaction of a monomer/curing agent is very temperature-dependent. This significantly shortens the working life. tides. good housekeeping.3 Viscosity—Polymeric adhesives are available with viscosities ranging from 15 centipoise (cps) to a paste-like consistency.2. or from temperature changes in the bonded composite. or other sources that could cause degradation. Section 2. 2. and used as binders for resin mortars and concretes. 2. Epoxies and two-component polyurethanes cure by the chemical reaction of the base resin and a curing agent. methacrylates. 2. (3. In the gel state. irreversible damage can be done to the bond with the substrate or the adhesive itself. Applying the adhesive to the substrate immediately after mixing lengthens the working life because most of the exothermic heat can be dissipated into the substrate without raising the temperature of the adhesive. adhesives require the use of protective clothing.2 Exothermic reaction—The chemical reaction of curing is exothermic and can accelerate cure rate. the ratio of the shear stress existing between laminae of moving fluid and the rate of shear between these laminae.2.1 describes the characteristics of polymeric adhesives prior to curing that are important in applying or installing the adhesive. resulting in the adhesive reaching the gel state at an elevated temperature. a material having this property is termed thixotropic or shear thinning (see rheology).3 Shrinkage—All adhesives shrink when they cure.4 mm) without external containment. and all cautions should be observed.1—Application characteristics 2. Polyesters.8 Adhesives are available that will stand in a bond line as thick as 1/4 in.4 The polymerization reaction is exothermic. The viscosity of the adhesive depends on the inherent viscosity of the base monomers and curing agents. Automatic metering and mixing equipment makes practical the use of adhesives with a very short working life.1 Gel—Cure of an adhesive is accompanied by an increase in viscosity and formation of a gel state before full cure. The addition of fillers to an adhesive system will reduce volumetric shrinkage but the inherent characteristics of a particular polymer system have by far the greatest influence . and personal cleanliness. and from exposure to moisture due to precipitation.9. Generally.4 Thixotropy—Very viscous adhesives are not necessarily thixotropic. When thixotropic properties of an adhesive are desired. and fiber laminates (mainly glass) adhesives. good ventilation. and thixotroping agents. If the adhesive is stressed during curing. and the measure thereof—specifically. In general. the ambient temperature.2 Curing—There are two mechanisms for curing adhesives. the longer the curing time. and the substrates also influence working time. the process being reversible. but is not affected to the same extent as viscosity by temperature. after mixing with a curing agent or other ingredient.1.7 The adhesive must cure quickly enough to obtain strength levels that can resist stresses that develop from removal of support of the bonded composite. resulting in lower strength.2 describes properties of these materials during and after curing that affect their suitability in achieving and maintaining an adhesive bond.6 Lower temperatures extend the curing time and higher temperatures shorten the curing time. Toxicity and hazard potentials vary widely from product to product. high temperatures will lower the thixotropic characteristic of the adhesive and lower temperatures will increase the thixotropy. 2.3 describes the features that distinguish each of the polymeric adhesives. the adhesive does not possess the physical or chemical properties it will ultimately achieve.1 Working life—Working life can vary from as little as 2 minutes to as long as 8 hours from one adhesive to another within each type of solvent-free adhesive. On a practical level. most adhesives will not effectively cure in a practical time at temperatures below 40 °F (4 °C). one-component polyurethanes. Section 2. High temperatures shorten working time and low temperatures lengthen working time. and the cure rate can be increased by the addition of an accelerator. polysulfides. 2.1. Holding a mixed adhesive in a mass in a mixing container increases the temperature of the adhesive because the beat cannot dissipate efficiently. The manufacturer’s literature and Material Safety Data Sheet (MSDS) for each product should be consulted.5 Toxicity and safety—Most components of solventfree adhesives prior to curing have some degree of toxicity and some are flammable. working life—the period of time when an adhesive. 2. Frequently.000 13. the modulus of all polymer adhesives is affected by temperature. is useful for field testing adhesive bonds.3. at most it can only be a small fraction of the elongation measured in ASTM D 638. Tensile strength of adhesives is most commonly measured by ASTM D 638.3.4 Flexural strength—As with tensile strength. It reduces the intimate contact between adhesive and substrate that is important for mechanical interlock and attraction of the adhesive molecules to the substrate surface. b./in. Adhesive strengths with concrete are usually measured in tension as a pulloff. Because the adhesive is bonded to the substrates it is not free to change its cross section by “necking down. Cohesive strength of the substrate materials.000 3 to 6 Polyester 600 to 13. c. Although the modulus of elasticity of polymeric adhesives used with concrete ranges from about 2% to no more than 20% of the modulus of elasticity of concrete. °F (ASTM D 648) Coefficient of thermal expansion. If the larger aggregate is not exposed.000 to 30. Cohesive strength of the adhesive./°C (ASTM D 696) Note: NR: not reported. 2.000 2 to 6 Polyurethane 175 to 10. See Table 1 for typical adhesive bond strengths. it also builds internal stress in the bond line.3.15 2. The pipe cap pulloff test described in ACI 503R-80. % (ASTM D 638) Compressive strength.000 15. 1).1 Bond strength—The strength of an adhesive bond depends on: a. this difference has an insignificant effect on transfer of load because of the very small volume of adhesive per unit area of bond line. manufacturers’ literature and technical references report physical properties at only one temperature.000 100 to 1000 20. (12. Appendix A. the cross section can become smaller without any external constraints. shear strength data can be used to determine if the adhesive has the strength required. The elongation in the test specimen is measured over a length of 1 in. The low-viscosity primer can provide more intimate contact with the substrate. its ability to elongate is severely restricted and the elongation achieved in the adhesive joint is not the same as in the test specimen.000 10 to 100 NR 100 to 200 Silicone 350 to 1000 20 to 700 NR NR NR 300 to 800 Styrene-butadiene 100 to 9350 20 to 1350 NR 3.3. in flexure in a bond line parallel with the direction of the applied load. psi (ASTM D 638) Tensile elongation. When this is so.000 290 to 370 165 to 209 48 to 80 NR 115 to 550 45 to 65 300 to 400 140 to 400 55 to 100 on shrinkage. Below the HDT. resulting in better adhesion. the change in modulus with temperature is modest (Fig.000 to 25.14 In all bonding/repair applications.6 Heat-deflection temperature (HDT)—Each polymer adhesive formulation has a specific HDT. the “length” of the adhesive in the direction of the tensile load can vary from a few thousandths to a tenth of an inch.3. The slant-shear test described in ASTM C 882 is the most useful and commonly used test. it is important to know the HDT to be able to anticipate if the physical properties at actual service temperatures will be . The “cross section” perpendicular to the tensile force can be literally thousands of square inches. psi (ASTM D 695) Compressive modulus at 73 °F. Tensile elongation as measured in ASTM D 638 is an indication of the relative stiffness of the adhesive. However. Adhesion of the adhesive to the substrate materials. 103 psi (ASTM D 695) Heat deflection temperature.3. Grease and oil-type contaminants will interface with the formation of a sound bond.6 to 120 <0 to 170 67 to 140 5000 to 9000 20 to 70 4000 to 14. adhesive materials have high flexural strength relative to concrete. The condition and strength of concrete at the surface is particularly important. If the shear forces in the bond line can be calculated. 2. In fact. especially near or above the heat-deflection temperature (HDT). Flexural strength of an adhesive is seldom a critical factor in adhesive bonding of concrete.SELECTIONOF OFPOLYMER POLYMER ADHESIVES WITH CONCRETE SELECTION ADHESIVES WITH CONCRETE Table 1—Polymer materials: typical physical properties (from Reference 26) Acrylic Tensile strength.2 mm) or less.” Thus. As the test specimen is loaded.11 Volumetric shrinkage from the uncured to the cured state varies from as low as 2% for filled epoxy systems to over 20% for some unfilled polyester systems. The application of low-viscosity primers improves adhesion of solvent-free adhesives that are more viscous or that have relatively poor molecular attraction to concrete.12 2. The bonded joint is only as strong as the weakest of these three strengths. (25 mm) with an initial cross section of 1/2 x 1/8 in. In an actual adhesive joint loaded in tension.2 Tensile strength and elongation—Because of the higher tensile strength of polymers relative to concrete. 10 /in.5R-5 869 Epoxy 4000 to 13.13. the tensile strength of an adhesive material itself is seldom a controlling factor.3—Properties of cured adhesive 2. Shrinkage works against good adhesion.5 Modulus of elasticity—The stiffness of polymer adhesives varies from rubber-like with some silicones and polyurethanes to glass-like with some methacrylate and polyesters (refer to Table 1). or in shear. the surface layer is considerably weaker than the concrete below the surface. –6 503.7 x 3. The numerical value determined in the test method for percentage of elongation should not be taken as the elongation that will take place in an adhesive joint. 2. the surface of the hardened concrete must be sound and clean.3 Shear strength—Shear strength is the most important property of adhesive materials commonly used to bond concrete. Shear strength is usually the only strength property for short-time loads that may be exceeded without the bonded concrete substrate failing first. Problems caused by the differences in thermal expansion of the adhesive and concrete can always be lessened by reducing bond-line thickness. duration of exposure. this difference bas not proven to be a problem. The performance of a bonded concrete structure or of an assembly of concrete adhesively bonded to other materials will depend on the insulation value and thermal conductivity of each of the bonded materials.13 Radiation resistance—Polymer materials are much more susceptible to radiation than inorganic materials such as concrete. Relative water resistance can be measured by water absorption tests such as ASTM D 570. Within a polymer type formulation. However. Incorporation of special fire-retardant additives and inorganic fillers allows the formulation of adhesives with fire resistance acceptable for some applications.19 Creep resistance can always be improved by reducing bond-line thickness. 68 to 100 °F (20 to 38 °C). low-modulus adhesives that are expected to maintain their flexibility over a long period of time.3.3. bond strength. The amount of aggregate that can be added is limited by the degree that workability is reduced and/or air voids result from too high an aggregate-to-adhesive ratio.11 Chemical resistance—The degree of chemical resistance varies greatly. However. Physical testing is required to quantify the effect of filler addition for each specific adhesive.3. creep resistance.21 2. within 7 days after placement. by increasing filler content of the adhesive as supplied by the manufacturer. the fire resistance of adhesively bonded concrete structures can be maintained within desired levels. (3.23-26 . not only between polymer groups. Chemical resistance of an adhesive in a bond line is often better than chemical resistance tables would indicate because only a very small surface area (the edges of the bond line) of the entire mass of adhesive is exposed to the chemical environment.2 mm) or less] bond line between two concrete elements or between concrete and steel. there can be a wide variation both between polymer groups and within a polymer group for resistance to water.9 Fire resistance—Polymers are combustible. Heat-deflection temperature is determined by ASTM D 648.3. 2. 1). variations can greatly influence radiation resistance. adhesive strength. or by hardening. Test data for a specific application and configuration should be required when a fire rating is required. However. Modulus of elasticity. as well as the temperature level (see Section 2.870 503. Accelerated aging data using elevated temperature aging for several days is often used as an indication of susceptibility to aging. 2. An analysis should be performed to estimate the actual temperature that may be reached. 2 for relative radiation resistance for polymer type groups. Through appropriate design. or by adding aggregate in the field. 2. the difference can cause failure in the concrete if the bonded elements are subjected to low temperatures (below 30 °F).3.6).3. when placed in thicker sections or used to bond materials with a greater thermal expansion and contraction than that of concrete. refer to Table 2 for comparison of the polymer groups.3. and the magnitude and direction of stress on the bond line.10 Age hardening—Most polymer adhesives develop over 90% of their strength at normal ambient temperature.12 Water resistance—Cured polymer adhesives have generally good water resistance.7 Creep resistance—Polymer adhesives have a much higher tendency to creep than inorganic materials such as concrete. and consideration should be given to the possibility that some of the bonded material may be consumed or removed by the fire. Adhesives are available for which long-term test data are available. 2.3. 1—Modulus of amine-cured epoxy (from Reference 38). either through the substrates or at the edge of the bond line (Table 2 gives a comparison of polymer groups). When the adhesive is confined in a narrow [1/8 in. Choosing an adhesive with a lower modulus of elasticity also helps to minimize stress caused by differences in thermal expansion but increases the danger of creep failure if the bond line is subjected to sustained loads. water resistance in service also depends on the degree of exposure of the adhesive to water.22 Age hardening is undesirable with flexible.8 Coefficient of thermal expansion—Polymer adhesives have coefficients of thermal expansion two to ten times that of concrete (refer to Table 1). a precise correlation between long-term tests at the expected service temperature and accelerated tests can be established only by conducting both tests. As with chemical resistance.20. Sustained loads at temperatures more than 18 °F (10 °C) above the HDT can result in creep to failure. and chemical and radiation resistance all begin to change at about 18 °F (10 °C) below the HDT and begin to fall off rapidly in a region beginning about 18 °F (10 °C) above the HDT16-18 (also see Fig. Refer to Fig.5R-6 ACI COMMITTEE REPORT CONCRETE REPAIR MANUAL Fig. including plaster coating of the concrete member to prevent burnout of the adhesive. curing continues and results in higher strength accompanied by higher modulus. 2. substantially different from those strengths reported in the published literature. as are most organic materials. However. but also from formulation to formulation within a polymer group. 2. reactive diluents. They are very tolerant of the alkalinity of concrete. in some cases. Epoxy adhesives conforming to ASTM C 881 will bond to concrete substrates and some will cure and bond underwater.27 Since resin systems (resin/curing agent) are available with viscosities lower than 100 cps and are in semi-solid form. This means that they can be tailored to a wide variety of strength and modulus requirements for a broad range of service temperatures.5R-7 871 Epoxy 25 °C S U S S S S S 65 °C S U S S S Q S Q U S Q Q U S Polyester 25 °C Q U S U Q U S 65 °C Q U S U U U Q Polyurethane 25 °C Q U S Q U Q S 65 °C U U S U U U S Q U S S S Q S Silicone 25 °C 65 °C Q U S Q S U S Styrene-butadiene 25 °C S U S S S U S 65 °C S U S S S U S 65 °C S U S S S U S Source: Reference 37. Epoxy adhesives generally have excellent adhesion because of relatively low curing shrinkage. Epoxy adhesives can be formulated to cure at temperatures as low as 0 °F (–18 °C) or to have a working life allowing use at 100 °F (38 °C). is second only to polyester adhesives. 2—Radiation resistance of polymer materials (from Reference 23). an amine or polyamid curing agent. Fig. Most epoxy adhesives have very low ratios of resin to curing agent. They are the most commonly used polymeric adhesives.1 Epoxy adhesives—Epoxy adhesives are generally composed of an epoxy resin.4. U = unsatisfactory. inorganic fillers and thixotroping agents.4—Distinguishing characteristics 2. Water and chemical resistance of epoxy adhesives after cure.SELECTIONOF OFPOLYMER POLYMER ADHESIVES WITH CONCRETE SELECTION ADHESIVES WITH CONCRETE Table 2—Chemical and water resistance: polymer materials* Acrylic 25 °C Nonoxidizing acids Oxidizing acids Aqueous salt solution Aqueous alkalies Polar solvents Nonpolar solvents Water * 503. Epoxies can be formulated with HDTs as low as 10 °F (–12 °C) or as high as 180 °F (82 °C) after curing at normal ambient temperatures.2 Polymer adhesives—Unsaturated polyester resins are generally dissolved in styrene monomer.4. They are cured . 2. Notes: S = satisfactory. they can be formulated into adhesive products that pour and penetrate but require containment in a bond line or into products that can fill gaps without being contained. and. as a class. 2. with low surface tension and molecular properties that enhance their attraction to a wide variety of substrates. which allows proper metering and mixing within the tolerances of available automatic equipment. Q = questionable. CHAPTER 3—WATER-BORNE ADHESIVES (LATEX AND LATEX-POWDER ADHESIVES) The only water-borne adhesives currently used to bond concrete are latex and latex-powder adhesives.1 Surface preparation—For both Type I and II adhesives. most polyester adhesive bonds to concrete deteriorate under constant wet conditions. low levels of anionic surfactants are incorporated to assist in polymerization or to result in specific latex properties. such as benzoyl peroxide. For Type II adhesives. The flowability of the mortar can be controlled by the amount of aggregate added. or in paste form in combination with water or inert organic liquids. Powder peroxides. they form an elastomer.4. Curing of polyesters can be accelerated by the addition of an accelerator component. unhardened concrete to hardened concrete. In almost all cases.28 However. promoters or accelerators are used to activate the decomposition of the initiator at room temperature.4. Some polyesters have relatively poor resistance to alkalis and solvents.1. This category includes most polyvinyl acetate and vinyl acetate copolymers. the surface should be damp.4. Polysulfide materials that are primarily joint sealants can be used to bond glass to concrete. They have limited use with concrete because of their low bond strength. The peroxides used as initiators. Polyacrylic esters and styrene-butadiene copolymers are included in this category. when in the pure state. polyesters have excellent resistance to acid environments.1—Application characteristics 3. which is designed to be used without further formulation. . Both types of adhesives are generally used for bonding fresh. Most polyesters do not bond well to damp or wet substrates and should not be used when these conditions exist.3 Acrylic adhesives—Methyl methacrylate and highmolecular-weight methacrylate monomers of the acrylic family are used as solvent-free adhesives for concrete. The use of accelerators that provide very short cure times requires mixing with automatic equipment.5R-8 ACI COMMITTEE REPORT CONCRETE REPAIR MANUAL with initiators. products with flash points over 100 °F (38 °C) are available. recent research has shown that some vinyl esters. 3. which have been described in the literature.872 503. thus enabling rapid low-temperature curing. and the vinyl ester of versatic acid.4. This type of adhesive gives a dried film that is redispersible upon application of water. Resistance to bond failure can also be increased by increasing the flexibility of the polyesters. Since the accelerator does not become an integral part of the polymer system. Type II latex adhesives are usually made with non-ionic surfactant systems such as alkyl phenols reacted with various levels of ethylene oxide. However. 2. which can provide full cure in approximately 2 minutes. intimate mixing with the monomer resin at a precise proportion is not required to achieve full cure. in general. Although water resistance of the polymer itself is good. The more common comonomers are ethylene. are extended with inert fillers or are supplied as emulsions. The accelerator is usually added at a very high ratio of resin/accelerator (100/1 to 100/10). they can be used to bond elements such as windows to concrete where a highly flexible adhesive is required to minimize concentration of stresses. In any event. Typically. but without any standing water. can bond under such conditions. There are two types of latex and latex-powder adhesives:30 Type I. The flexible types have been used in membrane systems and for bonding ceramic tile to concrete where impact resistance is required. This type of latex gives a dried film that is not redispersible.5 Polyurethane adhesives—Polyurethane adhesives are available as both rigid and flexible materials. and Type II. a type of polyester. Often. When combined with a polyol. the urethane forms a rigid polymer similar to epoxy adhesives. These formulations are sometimes referred to as “polysulfide adhesives.29 However. Latexes and latex powders are generally made by emulsion polymerization techniques. with flash points below 100 °F (38 °C). When combined with an aromatic amine. The mortar can be used as an adhesive to fill wide bond lines and provide a cure adequate for service in 30 minutes to 2 hours.6 Silicone adhesives—Silicones that have the ability to cure in a wide temperature range are almost exclusively used as flexible joint sealants. polyesters have found only limited use as adhesives.28 Epoxy or modified-urethane primers may be used to improve the overall bond strengths to concrete substrates if the primers are compatible with the polyester resin prior to use. Type II adhesives have occasionally been used for bonding hardened concrete to hardened concrete. However. prolonged storage of the initiators at elevated temperatures should be avoided to avoid decomposition of the peroxide. which is designed to be used in slurry form with a hydraulic cement.4 Polysulfide adhesives—Polysulfides are most frequently used as flexibilizers in epoxy resin formulations. 2. usually portland cement. Generally. Polyesters. thus providing some local stress relief during the application of external forces. butyl acrylate. the ratio of latex to cement is about one part latex solids to four parts of cement by weight.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 generally made using a polyvinyl alcohol (PVOH) surfactant system.29 2. usually an organic peroxide such as methyl ethyl ketone peroxide or benzoyl peroxide. Because of their relatively high shrinkage while curing. a primer composed of the methacrylate monomer cured with an organic peroxide is used to provide an improved bond to concrete. are considered flammable.” but they fit properly into the “epoxy adhesive” category. may decompose rapidly at elevated temperatures over 90 °F (32 °C) and may even cause fire or explosion. Silicone should not be used in applications requiring resistance to sustained loads. thus minimizing the explosion hazard. They are most commonly used by mixing with fine aggregate to form an easily flowable adhesive mortar. These adhesives generally share the same characteristics as polyester adhesives. 2. Films of the latex are redispersible. when properly applied. 3. When used as Type II adhesives. Although it is recommended that the fresh.33 3. The resulting bond is obtained from the penetration of the cement paste of the fresh concrete into the surface. the type of cement. 3. Curing of Type II adhesives depends on the rate of hydration of the cement in the slurry and also on evaporation of the water. satisfactory bonds have been obtained when the fresh. When tested by ASTM C 1042 method. The plasticizers are added to decrease the minimum film-forming temperature (MFFT). the length of which will depend on the type of latex. 3.1. 3. bond strengths (ASTM C 1042) usually exceed 1000 psi (6. and the vinyl ester of versatic acid are Type I adhesives but can also be used as Type II adhesives. are Type II latex adhesives.3 Water resistance—The water resistance of Type I latex adhesives has always been considered suspect because the latex film is redispersible and vinyl acetate hydrolyzes in the presence of moisture and high pH values to give watersoluble products (vinyl alcohol and a metallic acetate).3. and because the resultant product is not as water soluble as polyvinyl alcohol. whether Type I or II. application temperatures must either be above the minimum film-forming temperature (MFFT) or above 50 °F (10 °C). and the quality of the fresh concrete. ethylene.3. Consequently. unhardened concrete was placed up to 7 days after latex application. and acrylic copolymer latexes.4 Methods of application—Type I and Type II adhesives are usually applied by brush or roller. it may act as a bond breaker rather than an adhesive. It is important that the fresh concrete be placed while the latex-cement slurry is still wet.2.1 Bond strength—The bond strength of Type I and Type II latex adhesives will depend on the latex.2 Shrinkage—There is virtually no shrinkage associated with Type I and Type II latex adhesives because these 503. such slurries are used for waterproofing swimming pools and for corrosion protection of steel members. any shrinkage that occurs is caused by shrinkage of the fresh concrete.1 MPa).5 Application conditions—It is essential that the latex adhesive. 3. It is essential that the surface being coated be thoroughly damp. both because the comonomer reduces the hydrolysis of the vinyl acetate grouping. the working life of the slurry.1. 3.2 Vinyl acetate copolymers—Copolymers of vinyl acetate with such materials as butyl acrylate. The drying occurs as water is removed either by evaporation or by hydration of the cement in the fresh concrete. unhardened concrete can be applied whether the latex is still wet or has dried.2.3—Distinguishing characteristics 3. however. It has been postulated32 that these lower values may be caused by the larger particle size of such latexes. They could be used as Type I adhesives.3 Polyacrylic esters and acrylic copolymers—Polyacrylic ester latexes.SELECTIONOF OFPOLYMER POLYMER ADHESIVES WITH CONCRETE SELECTION ADHESIVES WITH CONCRETE This damp condition is conducive to penetration by the polymer particles of the adhesives into the hardened concrete. It is postulated that the function of the adhesive is to insure that the fresh concrete “wets out” the hardened concrete surface. Type II latex adhesives (slurries of latex and hydraulic cement) have excellent water resistance. unhardened concrete be placed within 24 hours of applying the latex. such as in rain or snow. will be from one to several hours. The adhesive is usually applied by brush or roller. in a relatively closed container. unhardened concrete causes redispersion of the latex polymer. when the adhesive and the fresh concrete are placed. In the latter occurrence. completely migrate into the hardened surface and the fresh concrete. In fact. water from the fresh. If the slurry has dried. while Type II adhesives give strengths usually in excess of 1200 psi (8. whichever is higher. in an open environment. They are generally made using primarily a nonionic surfactant system. Their water resistance is much better than that of polyvinyl acetate. but this is not recommended because the dried films are usually not redispersible. such as polyethyl acrylate. the type of hydraulic cement. This value is slightly lower than most other Type II latex adhesives. 3.1. Although the surface must be thoroughly damp when the latex adhesive is applied. Type II adhesives have a limited working life. Water resistance of such adhesives is suspect because of hydrolysis of the polyvinyl acetate. although other techniques such as spraying and troweling have also been used.2—Properties of cured adhesive 3. coalesces to form a polymer film.1 Polyvinyl acetate—Polyvinyl acetate latexes are Type I adhesives and are usually formulated with a plasticizer such as dibutyl phthalate or dipropyl glycol dibenzoate.1. 3. If this postulation is correct.5R-9 873 materials. They are generally made in polyvinyl alcohol surfactant systems and are available in latex and redispersible powder forms. Note that the dried film of the Type I latex adhesive must be kept clean from dust and other contaminants between the times of film forming and the application of the fresh concrete.2. which eliminates the need for the addition of plasticizers. Consequently. This type of adhesive is usually made in a polyvinyl alcohol surfactant system and is available both in the latex form and as a redispersible powder.2 Working life—Type I latex adhesives have a virtually unlimited working life because of their redispersible characteristic.32 3. and the environmental conditions. the adhesive and fresh concrete should not be placed during wet environmental conditions. drying can occur quickly and shorten working life to less than 30 minutes.3 MPa). and the fresh. The water resistance of such polymers will depend on the type and ratio of comonomer to vinyl acetate. The comonomer also causes a reduction in the minimum film-forming temperature. Typically. However. the quality of the hardened surface. this type of adhesive has been successfully used without apparent problems in areas exposed to moisture.3. and that the application technique be such that the adhesive completely “wets” the surface. it explains why moisture failures of Type I adhesives have not occurred where expected. Type I adhesives usually give bond strengths in excess of 300 psi (2.9 MPa).3 Curing—Curing of Type I adhesives depends on the cure of the fresh concrete because Type I adhesives cure by drying. If the latex dries before placement of the fresh . their surfactant system is primarily of the nonionic type. if adequate test data are not available. 4. the adhesive should be able to transfer loads to the same degree as the structural elements that are bonded together. 5.2.1—Type and magnitude of loads For permanent adhesive bonds. CHAPTER 4—ADHESIVE SELECTION CRITERIA This chapter describes the factors that can be important in choosing an adhesive for a specific application. the adhesive chosen must be able to tolerate its presence.5R-10 ACI COMMITTEE REPORT CONCRETE REPAIR MANUAL concrete. In addition. Factors that affect the installation and that the adhesive must be able to tolerate are described in the following sections. and aligning the concrete elements to be bonded.3. or dynamic loading is not available. chemicals. High temperatures may cause the adhesive to gel before it can be properly placed and the substrates joined.13. These groups can improve adhesion by ionic reaction with metallic radicals in the surface of the fresh concrete. Glass transition temperatures for such latexes are normally less than 18 °F (10 °C).1. the effects of high ambient temperatures (Sections 2. 4.1. a determination should be made of: • Direction (tension. the adhesive bond is used in conjunction with mechanical attachments. such as vinyl carboxylic acids. CHAPTER 5—ADHESIVES FOR BONDING OF HARDENED CONCRETE TO HARDENED CONCRETE Polymer adhesives are frequently used in segmental construction to bond together broken concrete.4 Surface accessibility—The accessibility of the surfaces to be bonded may dictate an adhesive with a long working time. the dried film can act as a bond breaker rather than as an adhesive. may be incorporated in the polymerization of these polymer latexes. but may also retard the initial hydration of the hydraulic cement. dynamic) • Duration • Frequency Most often data are available only for a single load rate while information on creep.1. For very critical adhesive applications. 4.3 Wetness of the substrates—The presence of water can seriously affect the ability of adhesives to bond to concrete or other construction materials. 4.1 Surface contamination—The presence of oils. positioning. The length of time that external supports for bonded elements may be in place during the curing of the adhesive can also influence the selection of the adhesive. it has been observed that such groups may retard the initial hydration of the hydraulic cement. They could be used as Type I adhesives but are not recommended for this category because their films are not redispersible.2 Temperature of the contact surfaces—The temperature of the contact surfaces and of the adhesive. fatigue. a working life of many hours is necessary.14 4. compression. 5.1. especially where several segments are assembled at one time. greases. If there is any chance that the surfaces to be bonded together will be damp. 3. field experience of an adhesive under similar service and environmental conditions can indicate the suitability of a polymer adhesive for a particular use. In bonding large segments. For each load. the bond line between concrete elements is seldom uniform.2 must be considered since cure time and working life for polymer adhesives are related.874 503.1.1—Important application characteristics 5. However. the strength of unreinforced joints decreases as the bond line thickness increases. such as vinyl carboxylic acids. 5. 5. Low levels (less than 2%) of reactive groups. when it is applied during the curing period of the adhesive. In most critical situations. the concrete elements cannot be realigned or adjusted without significantly reducing the bond strength that would be realized on full cure.4 Styrene-butadiene copolymers—Styrene-butadiene copolymer latexes are Type II adhesives. or with tendons that cross the bond line. especially if reinforcement does not pass through the adhesive joint. shear.2. 4. flexure) • Rate (static.2. dust. 5.2 Working life—The working life should be adequate to allow placing. have residual water on them. can be incorporated in the polymerization. with reinforcing steel. Alternately. however.7) must be considered.2—Important bond-strength considerations Although the published bond strengths for polymer adhesives may appear to be adequate for a specific hardened concrete to hardened concrete application. It must also be applied in a thickness that will completely fill any irregularities that exist between the surfaces to be bonded. In general.6 and 2.2. This tolerance can be demonstrated only by testing under the specific applications and service conditions expected. or be submerged. or any other foreign materials can interfere with achieving a good bond. will affect the rate of bond strength development. Except for match cast segments.2—Conditions during application Equally as important as the strength characteristics of the adhesive is whether it can be installed to provide the strengths that are achieved in controlled laboratory tests. and to attach elements such as facades to concrete structures. a test program should be conducted that simulates the load conditions expected.1 Viscosity and thixotropy—An adhesive for bonding hardened concrete to hardened concrete must be viscous and thixotropic enough not to run out of the bond line prior to forming a gel.4 Bond-line thickness—Recommended bond-line thickness requirements vary from one adhesive to another.3. Such groups can improve adhesion and latex stability.3. If a foreign substance cannot be completely removed. . Low temperatures may make the adhesive too viscous to apply properly.3 Cure time—When choosing an adhesive for its curing time. Once the working life has expired but before cure has taken place. the working life requirements described in Section 5. dirt. the adhesive specified must be compatible with moisture to achieve the required bond strength. Small levels of reactive groups. 8 MPa) for Type I and 1250 psi (8. In this case.1. Additionally. For general construction.2—Important bond-strength considerations Epoxy adhesives provide higher bond strengths than water-borne adhesives. (0. as it would be from only rough trowelling or chipping.1—Important application considerations 6. However. if the surface is rough. the concrete at the interface can be weakened enough to result in immediate bond failure. there must be a proper balance between adhesive curing time and concrete curing time. 7. if all faces of the crack are not sealed prior to filling the crack.6 MPa) for Type II water-borne adhesives. a thixotropic or psuedoplastic adhesive should be used which will stay in the crack without constraint. The only way to be absolutely sure of bond strength capability is to conduct one test.1. As an example. that the specific adhesive and concrete mixture to be used in the field application rather than the mortar mix specified for use in ASTM C 882 be used in the laboratory tests. unlike other solvent-free adhesives. 6. the adhesive must have enough thixotropy to maintain a uniform bond-line thickness without draining away from the high spots and into the low spots. application rates should be between 25 and 100 ft2/gal. and because they tolerate a wider range of moisture conditions in the plastic concrete and the hardened substrate.3 MPa) for an epoxy adhesive. or when the adhesively bonded concrete must be placed in forms. For vertical surfaces. The primary use of all types of water-borne adhesives with concrete is to bond plastic concrete to hardened concrete. if injection adhesives with viscosities lower than 100 cps are used. even without external loads. It is vital. the adhesive must tolerate water prior to cure of the adhesive. This is especially important in large concrete placements. CHAPTER 7—ADHESIVES FOR REPAIR OF CRACKS IN CONCRETE Epoxy adhesives are the most common adhesives used for crack repair. the 3 x 6 in. cylinder size specified in ASTM C 882 may have to be increased to provide a cylinder diameter to large aggregate ratio greater than three to one as prescribed in ASTM C 192. using the specific adhesive and concrete mixture (see Section 6. of course. can bond to a greater surface area of the larger aggregate. If the adhesive cures too slowly. even into subgrades. even among those used to bond fresh concrete. such as a modified ASTM C 882. There are wide variations in the sensitivity to water from one adhesive to another. Typical viscosities for liquid epoxy injection adhesives range from 100 to 500 cps at 77 °F (25 °C).1. For general construction applications. .61 and 2. as opposed to water-borne adhesives.5R-11 875 maximum bond-line thickness for water-borne adhesives is limited by their viscosity.21 7.2 Water sensitivity during cure—All cracks in concrete that is outdoors should be assumed to have water in them unless there is evidence to the contrary.1—Important application considerations 7. 6. 6. They are usually introduced into cracks by injection.SELECTIONOF OFPOLYMER POLYMER ADHESIVES WITH CONCRETE SELECTION ADHESIVES WITH CONCRETE CHAPTER 6—ADHESIVES FOR BONDING PLASTIC CONCRETE TO HARDENED CONCRETE Polymer adhesives provide a better bond of plastic concrete to hardened concrete than can be obtained by relying on the cement itself or on a cement slurry. the adhesive must be able to stand without running off. Polyesters and latex-cement slurries have been used very infrequently with either application method. High-molecular-weight methacrylates are also used on some flat-surface applications by flooding the surface with adhesive. In thicker bond lines.4 Bond-line thickness—There are wide variations in the recommendation of manufacturers regarding application rate which in turn determines bond-line thickness. they can be readily formulated to cure and bond in the presence of water. The only solvent-free adhesives used for bonding plastic concrete to hardened concrete are epoxy adhesives because.45 m2/L).3). 6. ASTM C 881 requires a minimum slant-shear strength of 1500 psi (10.1.1 Viscosity and thixotropy—Most applications of bonding fresh concrete to existing concrete are on relatively large areas. There are also great differences in the amount of water present in different concrete mixtures. 6. To place the adhesive economically.1.1. materials conforming to ASTM C 881 or ASTM C 1059 have proven to be satisfactory.5 Water sensitivity—By the very nature of the process of bonding fresh concrete. depending upon the surface profile. 6. it is desirable to use an adhesive that is sufficiently low in viscosity to be sprayed or applied by a roller or squeegee.1 Viscosity and thixotropy—Low viscosity is required for adhesives to penetrate cracks without using high injection pressure.3 Cure time—With solvent-free adhesives. because polymer adhesives shrink less than cement paste upon curing. the adhesive can penetrate into the concrete so far that it leaves a starved bond line.1.1. it may not have the strength in its uncured state to resist curling caused by curing shrinkage of large thin section concrete placements that are unrestrained. Highmolecular-weight methacrylates have viscosities in the range of 15 to 20 cps at 77 °F (25 °C).2 Working life—The working life of an adhesive used for bonding fresh concrete must be long enough to allow workers time to place the concrete before the adhesive gels. The 503. For epoxy adhesives. If the adhesive cures before the shrinkage in the curing concrete takes place. However.18. whereas ASTM C 1059 requires a minimum of 400 psi (2. An adhesive that will bond in the presence of water should be used whenever water is present in the crack. A modified ASTM Test Method C 882 can provide assurance that the proper balance of cure rates exist. Rough surfaces actually have greater true surface areas than smooth surfaces of the same dimensions. there must be a continual reservoir of adhesive available to the crack until the adhesive gels to fill the bond line. For cracks where all faces cannot be sealed. and they have been used occasionally to inject into fine cracks because of their low viscosity. epoxy adhesives conforming to ASTM C 881 have been found to be adequate. epoxy adhesives. Liquid adhesives without thixotropic properties will also drain out of a crack. 8.3 Concrete temperature—Cracks in concrete open and close as the temperature of the concrete changes. (Refer to Section 2. an adhesive conforming to ASTM C 881 Type IV should be used. an injection adhesive should be chosen that cures fast enough to resist the tensile forces that result when the crack widens from temperature change. a liquid adhesive can be used.2 Hole diameter—Hole diameters normally used are 1/8 to 1/2 in.30. Unless it can be determined that the adhesive in a crack will not be subject to sustained loads.3.34 8. it must be capable of being pumped from the bottom (back) of the hole toward the front of the hole to avoid trapping air bubbles in the bond line. As the annulus dimension increases.876 503.1. Anchor spacing should allow a sufficient quantity of anchors to transfer the desired loads from the attached members without development of excessive stress interaction through the concrete between the anchors. and allows placement when the location has not been decided prior to the concrete setting of the concrete. no standard tests exist.7 mm) greater than the bolt. For specific guidelines for hole depth and spacing for steel anchorages. and it is much less likely to trap air in the bond line.1 Limitations—Adhesive bonding of cracked concrete may not be permanent if the original cause of the crack is not eliminated. the concrete structure will probably crack again in the vicinity of the original crack. The effective modulus of elasticity of a flexible adhesive in a crack is substantially the same as that of a rigid adhesive. CHAPTER 8—ADHESIVES FOR BONDING INSERTS INTO CONCRETE Solvent-free polymer adhesives have been widely used to bond or grout anchorages and reinforcing steel into concrete. In all cases.15 7. Which application conditions are important depends on which combination is used. Glass capsules containing both the resin and the initiator or curing agent have been widely used to bond anchors in concrete. Therefore. a wider variety of adhesives is required because of the very different characteristics of each of these materials. and protection plates. Factors such as these should be considered before repairing the original cracks.2.1—Important application considerations 8. and plastics.7). For other construction materials such as aluminum.) 8. creep resistance should be carefully considered (see Section 2.1—Important application considerations There are innumerable combinations of types of adhesive and types of construction materials that can be bonded to concrete. 7. 7. Air bubbles would reduce contact area and result in a weakened bond. CHAPTER 9—ADHESIVES FOR BONDING CONCRETE AND OTHER MATERIALS Epoxy and some polyester adhesives are commonly used for bonding steel in the form of inserts (see Section 8).2 to 12. the steel should generally be embedded to a minimum depth of ten times its diameter.” Appendix B. rubber. This test evaluates the ability of the adhesive to bond and cure under the conditions of moisture and surface preparation actually encountered in application. Steel Embedments. 8. Special laboratory or field tests should be conducted to qualify an adhesive for underwater injection. For adhesive injection into cracks underwater. The ability of the concreteanchor system to develop full pullout strength of the anchor as determined by ASTM E 488 depends mostly on the bond strength of the adhesive and the cleanliness of the hole.3 Creep resistance—Frequently the adhesive in a bonded crack will be subjected to sustained loads. the smaller the annulus between the insert diameter and the hole diameter. the lower the possibility of creep failure. “Code Requirements for Nuclear Safety Related Concrete Structures.2 Creep resistance—Many inserts that are bonded into concrete are put under a constant load. 7. glass.3.2. For critical applications. external28. wood. as the anchor is inserted and twisted. For vertical overhead and horizontal holes. 8. Since each application is unique.1 Viscosity and thixotropy—For vertical holes with the opening upward.2.5R-12 ACI COMMITTEE REPORT CONCRETE REPAIR MANUAL Conformance with ASTM C 881 Type IV or ASTM C 1059 will assure that a satisfactory adhesive is chosen. A liquid adhesive requires less time to place than a paste or thixotropic or psuedoplastic adhesive.2. This procedure avoids the difficulties of maintaining the location of an insert during a concrete placement.1.7. 9. if overloads continue to exist or if foundations continue to settle.29. However. there is little information available except in the manufacturer’s literature. The capsule is placed in the hole in the concrete. Examples are fixtures being hung from anchorages and torqued anchor bolts. . a thixotropic or psuedoplastic paste adhesive is more suitable because it will not require containment to keep it from running out of the hole. ASTM C 882 has been used for this purpose by fabricating the test specimens underwater.1 Pullout strength—Pullout strength is generally determined by applying an axial tensile load to the anchorage until tensile failure occurs.35 or internal36 reinforcement.1. pre-testing of a mockup is recommended because no standard test methods are currently available. dowel.3 Hole depth and spacing—To develop the full strength of a steel anchor or a reinforcing bar.2—Important strength considerations 7. as opposed to inducing a failure in the concrete. or insert diameter.2.2 Flexibility—The use of a low-modulus flexible adhesive in a crack will not allow any significant movement of the concrete structure for the reasons cited in Section 2. These loads may be external or they may be caused by restraints on a structure that is undergoing cyclic temperature changes.2—Important strength considerations 8.2.1. see ACI 349. the capsule breaks and the adhesive is mixed. If a crack cannot be injected while it is in its widest position. (3. Standard test methods do not exist. For example.3. The two components are separated in the capsule as supplied by the manufacturer. the potential for creep failure under constant load increases. Changes in moisture content that cause the wood to shrink or swell after the adhesive has cured will stress the bond line and can cause failure of the wood fibers. In many cases. they are much more difficult to bond with polymer adhesives.4 Plastics. because any film of oil or other foreign substance that may not be visible can interfere with the bond. The working life of an adhesive applied to a steel surface may be much shorter than would be expected if the ambient temperature or the adhesive temperature in the mixing container is used to predict working life. 9.1. For this reason. special tests must be designed unless field experience for the exact combination of adhesive and material to be bonded to concrete can be demonstrated for the same service conditions. Because of the much higher modulus of elasticity of the steel compared to the polymer adhesive. If a dry surface cannot be assured. and rubber—There is wide variation in chemical and physical properties among the different rubber and plastic materials. polyurethane. and grain characteristics of the many woods used in construction makes it impossible to generalize on the suitability of a type of polymer adhesive for bonding wood. 9. reinforced plastics. In either case. Because the surface energy of most rubber and plastics is much lower than that of steel or concrete. For this reason. an adhesive should be chosen that will bond to wet steel.3 Glass—The brittle nature of glass requires that an adhesive be used that will minimize stresses at the bond line caused by temperature changes or external forces. Because of its high heat capacity.1. Steel that is exposed to the sun may reach temperatures as high as 170 °F (77 °C). Some of the more common factors to consider are listed in the following paragraphs for the general classes of construction materials. Even if the adhesive does not fail immediately upon removal of the clamps. care must be taken not to stress the steel with the application of clamps that will be removed once the adhesive cures. the steel can exert stresses on the bond line that exceed the strength of the adhesive.1.1. the surface must be oxidized or otherwise chemically treated to provide a bondable surface. which can cause creep failure at a later time. 9. 503. changes in steel temperature can lag behind changes in atmospheric temperature and cause condensation of water vapor on the surface of the steel. Some rubber and plastic materials contain nonreactive plasticizers used to enhance their physical properties. Particular attention should be paid to providing a dry surface. constant stresses will be built into the bond line. only silicone. an adhesive primer is used if maximum corrosion resistance is required. and very low-modulus epoxy adhesives are usually used to bond flexible plastics or rubber to concrete. The particular adhesive and wood combination should be tested at the wood moisture content that is expected when the adhesive is applied. The presence of the plasticizer on the surface can prevent a good bond from being achieved.1 Steel—If it is necessary to hold a steel plate in place while the adhesive cures. 9. .1.SELECTIONOF OFPOLYMER POLYMER ADHESIVES WITH CONCRETE SELECTION ADHESIVES WITH CONCRETE For critical applications. Particular attention should be paid to the surface condition of the glass. the adhesive can be subjected to peel forces when the plastic or rubber substrate is loaded in a manner that tends to deform the substrate at the bond line. aluminum is usually prepared for adhesive bonding by treatment with a chromicsulfuric acid mixture or by anodizing if a long lasting corrosionresistant bond is desired. density. Migration of the plasticizer to the bond line after the adhesive is cured and bonded can cause deterioration of the adhesive bond.5 Aluminum—Because of the rapid formation of oxide on a freshly abraded aluminum surface.2 Wood—The wide variety of chemical. 9. In the bond of a flexible plastic or rubber to concrete. only silicone and polysulfide materials are usually used for bonding glass to concrete.5R-13 877 Standard laboratory tests are not available either for bonding wood to concrete or for the effect of changes in the moisture content of wood. VAE VAC E. PAE. A. P. PP E. P. P. PVA. M E. P. PP E. SB. PAE. M E. PAE. M E. Evaluation. P. PP E. S E. PP. PP E. CHAPTER 11—REFERENCES 11. P. M E. and Repair of Cracks in Concrete Structures 503R-80 Use of Epoxy Compounds with Concrete 503. PP E. M. A. M. PP E. Steel. P. S E. M E. P. P. P. generally in minor detail only. PP E. M E. M E. PVA. P. SB. PA E E E. M Water resistance Conditions for use of adhesives Plastic concrete to cured concrete Cured concrete to cured concrete Cracked concrete Cured concrete to other materials with similar CTE and EM Cured concrete to other materials with dissimilar CTE and EM Anchoring bolts ABBREVIATIONS: E: epoxy P: polyester M: methylmethacrylate monomer PP: polysulfide and polyurethane S: silicone PAE: acrylic latex SB: styrene-butadiene latex PVA: polyvinyl acetate latex CTE: coefficient of thermal expansion EM: elastic modulus VAC: vinyl acetate copolymer latexes Application requirements of adhesives Temperature — E E E E. the user of this document should check directly with the sponsoring group if it is desired to refer to the latest revision. M E. M E. SB. M. P. P. P. Since some of these documents are revised frequently. PP. SB. M E. P. S E. PA E. M E.878 503. P. P. M Below 2000 psi (13. PP E — E. P. P. M E.1—Specified and/or recommended references The documents of the various standards-producing organizations referred to in this document are listed with their serial designation. M E. including year of adoption or revision. PAE E. M. P. M E.8 MPa) E E. VAC E E. M E. The documents listed were the latest effort at the time this document was revised. M E. M. P. PP E.8 MPa) Water resistance Moisture Submerged E E.1-79(86) Standard Specification for Bonding Hardened Concrete. SB. M CAUTION: The listing of a particular type of adhesive as suitable for an adhesive requirement indicates that many adhesive products of that type meet the requirement. PP. American Concrete Institute 224. SB. M E. Brick and Other Materials to Hardened Concrete with a MultiComponent Epoxy Adhesive 503. M Moist substrate E. M Temperature resistance Below 32 °F (0 °C) Above 120 °F (49 °C) E. M. SB. P. PP. P.2-79(86) Standard Specification for Bonding Plastic Concrete to Hardened Concrete with a MultiComponent Epoxy Adhesive ASTM C 192-88 Specification for Making and Curing Concrete Test Specimens C 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 Concrete C 1042-85 Test Method for Bond Strength of Latex Systems Used with Concrete C 1059-86 Specification for Latex Agents for Binding Fresh to Hardened Concrete D 570-81 Test Method for Water Absorption of Plastics D 638-89 Test Method for Tensile Properties of Plastics D 648-82(88)Test Method for Deflection Temperature of Plastics Under Flexural Load D 695-89 Test Method for Compressive Properties of Rigid Plastics D 696 Standard Test Method for Coefficient of Linear Thermal Expansion of Plastics Between –30 °C and 30 °C With a Vitreous Silica Dilatometer D 907 Standard Terminology of Adhesives . The purpose of the chart is to guide the designer to a generally appropriate adhesive type but the designer must verify that the specified adhesive product meets the performance and application requirement for each particular project. It does not mean that all adhesives of that type meet the application or performance requirement. E. M — E. M — — E.1R-84 Causes. P. PP E.5R-14 ACI COMMITTEE REPORT CONCRETE REPAIR MANUAL CHAPTER 10—QUICK REFERENCE GUIDE Performance requirements of adhesives Bond strength (ASTM C 882) Conditions for use of adhesives Plastic concrete to cured concrete Cured concrete to cured concrete Cracked concrete Cured concrete to other materials with similar CTE and EM Cured concrete to other materials with dissimilar CTE and EM Anchoring bolts Above 2000 psi (13. S E. P. P. P. M E. Wood. M E. PAE E E E Submerged substrate Below 32 °F (0 °C) Above 100 °F (38 °C) Ability to flow into narrow voids — — E. V. 1960. 29.. by F. V.” Final Report.. 1973. pp. 1967.. V.” Rubber and Plastic Processing. U. DC.. 576-619. Oct.. and Moreadith. 24. D. Sahli.. 69. 17.” Modern Plastics. C. 19. pp.” Concrete International. F.. Essex. D. Marcel Dekker. 2. 1988. 3-4. 1985. 1972. V.. National Science Foundation. Rodriguez.. McGraw-Hill Book Co. C. Wake. Adams. 1999. 18. 400-403. 1988. 33. May 1988. W. “Fire Research on Seismically Damaged Concrete Beams Repaired with Epoxy Adhesives. 205-215. and Hiremagular. Sept. McGraw-Hill. 9. Jones. J. 1988. E. H. Swamy. 7. “Surface Preparation for Adhesives. Epoxy Resins... and Neville. Federal Highway Administration.2—Cited references 1. 122-124. N. 1984. B. V. ASTM C 1059. 2. Handbook of Epoxy Resins. W. Nov. W. I. Eirich. 1978. Plecnik.. Modern Plastics Encyclopedia 89. pp. Essex.. pp. 1967. 18. W.. pp. “Kansas Bridges Renovated by Post Reinforcement and Thin Bonded . Stratton. John Wiley & Sons. No. Kinloch. “Composite Behavior of Concrete Beams with Epoxy Bonded External Reinforcements. pp. K.. and Diba. Organisation Europeenne pour la Recherche Nucleaire. “How Plastics Perform Under Nuclear Radiation. 62-65. “Fire Testing Epoxies. 22. 11. 15-20. and Wake. F. pp.. Physical Aging in Amorphous Polymers and Other Materials. and Wake. Blorham.. Nov. No. 25. Elsevier Applied Science Publishers. 1977. 2. No. 32. F.. 134-135. and Crumpton. Parra.. 44-47. Encyclopedia of Chemical Technology. 1984. No. 129-132. C. New York. Dec... 1985. pp. 29. “How Radiation Affects Polymers... “Curing Properties of Thermosetting Polymers. 35. Van Nostrand Reinhold Co. pp. 6-25 to 6-27. Diba. May-June 1963. Elsevier Applied Science Publishers. New York. 17-22. 2nd Edition. Dec. 1984. pp. 8.. pp.. W. Handbook of Epoxy Resins. New York. pp. Contract No... D. 3. 10. 7. Lewis and R. and Restat. M. “Application of Adhesives to Steel Bridges. Skeist.. 62-65.” paper presented at the American Concrete Institute’s Fall Convention. 1977. V. 1987. Houston. Van Nostrand Reinhold Co. “Polymer-Modified Mortars and Concretes. 23. 14. Academic Press. New York. S. D. V. No. New York.. Cannon. Essex. Gaul.. Y. Van Nostrand Reinhold Co. P. 13.. 36.. and Neville. 53-55. Structural Adhesive Joints in Engineering. New York. Howard. Adams... London and New York. M. 11.” FHWA/RD 87/037. July 1984.. A. A..” International Journal of Cement Composites. “Structural Applications of Adhesives in Civil Engineering. G. R. R. 28. Apr. H.. Plecnik. Chapter 7. 16.. West Conshohocken. Handbook of Adhesives. F. pp. J. Schonbacher. Rheology Theory and Applications. “Standard Specification for Latex Agents for Bonding Fresh to Hardened Concrete.” by J. pp. Albrecht. 25-7 to 25-11. “Preparing Concrete Surfaces for Coatings. New York. 1978. C. 11. K. New York. New York. 8-13. C. A.” Materials Science and Technology. R.” Construction Canada. Selecting Guide to Organic Materials for Nuclear Engineering. V. 64-68.. Gaul. Nov.” Concrete International.. 503. 8. Crute. D. Van de Voorde. pp. New York. A. 3. 6-29 to 6-30. Y.. 26. I. Ramachandran. “Introduction to Adhesives. 1983. Pa. J.5R-15 879 The publications may be obtained from the following organizations: American Concrete Institute PO Box 9094 Farmington Hills MI 48333-9094 ASTM International 100 Barr Harbor Dr West Conshohocken PA 19428-2959 11. C.. 1970. 1984.... J. 1986.. Amsterdam. and Wake. pp. No. and Evans. 1-6.” Concrete International. No. J. Lee. V. p. Skeist. p. 31. 4. New York. “Latex Adhesives for Bonding Concrete. 121-125. A. 12. R.. C. pp.” Concrete Admixtures Handbook. 23-24.SELECTIONOF OFPOLYMER POLYMER ADHESIVES WITH CONCRETE SELECTION ADHESIVES WITH CONCRETE E 488-88 Test Method for Strength of Anchors in Concrete and Masonry Units 503. M. 2nd Edition. Principles of Polymer Systems. W. PFR-7927222. 9. Plecnik. A. Principles of Polymer Systems. 9. and Tanaka.. 3. I. Lee. Dept. Rodriguez. 6. TX. 53-55. Mays. 937-942. 6-3 to 6-4. 1982. C. K. pp. Structural Adhesive Joints in Engineering.. P. I. Handbook of Adhesives.. 65. New York and London. Godfrey. J. Structural Adhesives—Developments in Resins and Primers. C... R.. Adams. Lee. McGraw-Hill Book Co. p. 46. 1989.. Gillham. H.. Murray.. A. V. Structural Adhesive Joints in Engineering. pp.. 30. 21-28 to 21-30.. L. 6. Elsevier Applied Sciences Publishers.” Concrete International. pp. “State-of-the Art Adhesives for Concrete Construction. Aug. 21. McGraw-Hill Book Co. 20.. and Beuderbalah. D. R. 12. R. H. O. Chemistry and Technology. Albrecht. pp. 400-407. New York. pp. 27. C. Inc. pp. Handbook of Adhesives. “Guide to the Design of Anchor Bolts and Other Steel Embedments. McGrawHill. 1984. London and New York. V. Adhesion and the Formulation of Adhesives. 28-41. May. Elsevier Applied Science Publishers. 15. ed. R. 30. No. 2nd Edition. Walters. pp. Elsevier Scientific Publishing Co.. Walters. R. W. Struk. McGraw-Hill. 160-162. Geneva. 3. F. J. Ohama.” ASTM International. 1970. Handbook of Epoxy Resins. 1-46. 7. 1967. 5. 2 pp. pp. “What are Latexes?” Concrete International... K. A.. 1984. Washington. of Transportation. 4. and Neville. McGraw-Hill. V. Noyes Publications. Saxon. A. Skeist. G... F. July 1981. W.” Chapter 6. 1. 34. M.S. 1977. J. Plecnik. D.. Modern Plastics Encyclopedia. May 1980. Applied Science Publishers. . 295-297. R. June 1971. 1984. May. 2. 1986. JMCSA. and Panek. “Epoxy Adhesives for Concrete and Steel. Construction Sealants and Adhesives. 147-262.. T. pp. Feb. “Strength and Behavior of Rebar Dowels Epoxy-Bonded in Hardened Concrete. Marcel Dekker. Plecnik. Seymor. V. Transport and Road Research Laboratory. J. No. C. R.. New York. Graduate School of Engineering.880 503. Plastics Versus Corrosives. Y. Tilmans.. ACI 503. Chemistry and Technology.. and Tanaka. John Wiley & Sons.” Concrete Construction. 347. Crowthorne. Cook. No. P. E.” Supplementary Report 529. M. J... J. A. J. New York.” Concrete International. 705-709. 1984.. M. 11.5R-92 was submitted to letter ballot of the committee and approved in accordance with ACI standardization procedures. pp.” thesis. 46-50. Inc.. and Howard. “Epoxy Penetration. C.. p. P. 2nd Edition. M.” Proceedings. pp. C.. and Krokosky. 1973. 6. Gaul. 37. pp. 1979. Luke. Hugenschmidt. Aug.5R-16 ACI COMMITTEE REPORT CONCRETE REPAIR MANUAL Concrete Overlay. Epoxy Resins.. pp. Cousins. A. . B. 1984.. 1982. J. 8.3—Additional references Calder. R. London.” Journal of Materials. W. A. V. Pham. “Exposure Tests on Externally Reinforced Concrete Beams—First Two Years. John Wiley & Sons. F. “Effect of Radiation on Some Mechanical Properties of an Epoxy System. University of Texas at Austin. J. New York.. 38. 465-481. 2. First International Congress on Polymer Concretes... May 1975.