1、AC1 503.5R-92 Guide for the Selection of (Reapproved 1997,2003) Polymer Ad hesives with Concrete Reported by AC1 Committee 503 Raymond J. Schutz chiniyn Milton D. Andmon* Roger W. Black John P. Cook FloydE. Dimmick Wolfgang D. Eisenhut Jack J. Fontma* Paul R. Hollenbach Subcommittee who pqmd the qat
2、 Robert W. Gaul* Subcommittee chairman David P. Hu T.Michae1 Jackson Troy D. Madeley Albert Mayer Joseph A. McElroy* Paul F. McHale Peter Mendis* Mylcs A. Murray secreouy Richard Montani Joseph M. Plecnik Hamid Saadatmanesh W. Glenn Smoak Joe Solomon Michael M. Spnnkel Douglas G. Walras* This guide
3、proiddes the engineer, contractor, and architect with a de- scriptioii of tlievariotis types of polymer adliesives (epoxy. polyester, acrylic, plyurethane, polysufide, silicone, vinyl acetate, and styrene butadiene) most frequently used for adhesive bonding of fresh con- crete to aired concrete, rep
4、air of cracks in concrete. bonding con- crete to other materials, and adhesive grouting of bolts and other in- serts into concrete. The guide emphasizes the factors that should be considered where selecting astructural adhesive, including characteristics during instal- lation and in sendce.The benef
5、ts and limitations of adhesive bond- ing are discussed for each application. 3.1-Application characteristics 3.2-Properties of cured adhesive 3.3-Distinguishing characteristics 4.1-Type and magnitude of loads 4.2-Conditions during application rbinr. 4 irlr; pairara; poldfdc; Pol-; rcpoirr; ding; m*e
6、rali$y for example, in concrete work, the epoxy resins. Age hardening - The progressive change in the chemical and physical properties of an adhesive, lead- ing to embrittlement. Bond line - The interface between two surfaces bonded together with an adhesive. Catalyst - A substance whose presence in
7、creases the rate of a chemical reaction. In some cases the catalyst is consumed and regenerated, in other cases the cata- lyst seems not to enter into the reaction, but functions by virtue of some other characteristic. Cohesive - The type of molecular attraction that holds adhesives and other materi
8、als together. Cohesive failure - A failure by separation within the adhesive itself, or within the substrate, rather than in the adhesives bond to the substrate. Copolymerization - Polymerization of two or more dissimilar monomers. Crosslinking agent - A substance that increases the molecular weight
9、 of a polymer by chemically linkuig and bridging the polymer chains. Cure- To change the properties of a chemical (usu- ally a polymer) by increasing its molecular weight by polymerization or crosslinking, usually accomplished by the action of heat, catalyst, crosslinking agent, curing agent, or any
10、 combination, with or without pressure. Curing agent - A substance that accelerates or par- ticipates in the curing of chemicals, sometimes referred to as a hardener. Elastomeric- Pertaining to a substance which has rubberlike properties. Emulsion - A two-phase liquid system in which small droplets
11、of one liquid (the internal phase) are im- miscible in, and dispersed uniformly throughout, a sec- ond continuous liquid phase (the external phase). POLYMER ADHESIVES 503.5R-3 Epoxy resins - A class of organic chemical bonding systems used in the preparation of special coatings or adhesives for conc
12、rete or as binders in epoxy resin mortars and concretes. Exothermic -Pertaining to a chemical reaction which occurs with the evolution of heat. Flexibilizer - A substance that is mixed with a more brittle material to make the latter more ductile. Gel -A colloid in which the dispersed phase has combi
13、ned with the continuous phase to produce a vis- cous jelly-like material. Glass transition temperature - The temperahire or range of temperature at which polymeric materials change fi-om a rigid, glass-like state to an elastomeric- like state. Heat deflection temperature (HDT) - The tempera- ture at
14、 which a plastic material reaches an arbitrary de- flection when subjected to an arbitrary load and test condition. It can be an indication of the glass transi- tion temperature, although these two temperatures are not necessarily equal. Initiator - A substance that causes a chemical reac- tion (suc
15、h as polymerization or curing) to start. The term usually applies 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 latex have sufficient mobi
16、lity and flexibility to coalesce into a continuous film. Monomer -An organic liquid, of relatively low molecular weight, that creates a solid polymer by react- ing with itself or other compounds of low molecular weight or both. Plasticizer - A substance added to polymer or co- polymer to reduce its
17、minimum film forming tempera- ture andor its glass transition temperature. Polyester - One of a large group of synthetic resins, mainly produced by reaction of unsaturated dibasic ac- ids with dihydroxy alcohols; commonly prepared for application by mixing with a vinyl-group monomer and fi-ee-radica
18、l catalysts at ambient temperatures and used as binders for resin mortars and concretes, fiber lami- nates (mainly glass), adhesives, and the like. Polymer - The product of polymerization; more commonly a rubber or resin consisting of large mole- cules formed by polymerization. Polymerization - Ther
19、eactioninwhchtwo ormore molecules of the same substance (monomer) combine to form a compound containing the same elements, but of high molecular weight. Polyol - A polhydric alcohol, i.e., one containing two or more hydroxyl groups. Polysulfide - Synthetic polymers obtained by the reaction of sodium
20、 polysulfide with organic dichlo- rides. Polyurethane - Reaction product of an isocyanate with any one of a wide variety of other compounds containing an active hydrogen group; used to formu- late tough, abrasion-resistant coatings. Polyvinyl acetate - Colorless, permanently thermo- plastic resin; u
21、sually supplied as an emulsion or water- dispersible powder characterized by flexibility, stability towards light, transparency to ultraviolet rays, high di- electric strength, toughness, and hardness; the higher the degree of polymerization, the higher the softening temperature; may be used in pain
22、ts for concrete. Promoter - Substances, which added in small quan- ities, increase the activity of catalysts, as well as in- crease or promote polymerization activity. Pseudoplastic - Often referred to as thixotropic, a substance whose viscosity decreases with increasing shear. Rheology - The scienc
23、e dealing with the flow of materials. Silicone - A resin, in which the main polymer chain consists of alternating silicon and oxygen atoms, with carbon containing side groups; silicones may be used in caulhg or coating compounds, admixtures for con- crete, or as adhesives. Substrate - A material upo
24、n the surface of which an adhesive is spread for the purpose of bonding. Surface-active agent - A substance that markedly affects the interfacial or surface tension of solutions even when present in very low concentrations. Surface energy - The interfacial free energy per unit area of the boundary b
25、etween the surface of a sub- strate and the air above it. Surface tension - A measure of surface energy, arising from molecular forces at the surface of a liquid, which tend to contain the volume to a minimum sur- face area. Surfactant - A contraction of the term “surface-ac- tive agent“. Thermoplas
26、tic - Becoming soft when heated and hard when cooled. Thermosetting - Becoming rigid by chemical reac- tion and not remeltable. Thixotroping agents - A substance incorporated into an adhesive to impart thixotropy. Thixotropy - The property of a material that ena- bles it to stiffen in a short period
27、 of time on standing, but to acquire a lower viscosity on mechanical agita- tion, the process being reversible; a material having this property is termed thixotropic or shear thuinuig (see Rheology). Vinyl ester - One of a group of synthetic resins pro- duced by the reaction of acrylic with epoxy re
28、sin or Bisphenol A, and 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, and fiber laminates (mainly glass) adhesives. Viscosity - The property of a material which resists c
29、hange in shape or arrangement of its elements during flow, and the measure thereof. Specifically the ratio of the shear stress existing between laminae of moving fluid and the rate of shear between these laminae. 503.5R-4 AC1 COMMITTEE REPORT Working life -The period of time which an adhe- sive, aft
30、er mixing with a curing agent or other ingredi- ent, remains sufficiently workable to permit spreading and application. CHAPTER 2 - SOLVENT-FREE ADHESIVES Solvent-free adhesives cure by polymerization of monomeric resins. Section 2.1. describes the character- istics of polymeric adhesives prior to c
31、uring which are important in applying or installing the adhesive. describes properties of these materials during and after curing which affect their su achiev- ing and maintaining an adhesive bon .L. .i. de- scribes the features that distinguish each of the poly- meric adhesives. 2.1- Application ch
32、aracteristics 2.1.1 Working Zqe - Workmg life can vary fi-om as little as 2 min to as long as 8 hr fi-om one adhesive to another within each type of solvent free adhesive. In general, the longer the working life, the longer the cur- ing time. Automatic metering and mixing equipment makes practical t
33、he use of adhesives with a very short working life.3 The temperatures of the adhesive components, the ambient temperature, and the substrates also influence workmg time. High temperatures shorten working time and low temperatures lengthen working time.4 The po- lymerization reaction is exothermic. H
34、olding a mixed adhesive in a mass in a mixing container increases the temperature of the adhesive because the heat cannot dissipate efficiently. This significantly shortens the workmg life. Applying the adhesive to the substrate immediately after mixing lengthens the workmg life be- cause most of th
35、e exothermic heat can be dissipated into the substrate without raising the temperature of the adhesive. 2.1.2 Curing -There are two mechanisms for cur- ing adhesives. Epoxies and two-component polyure- thanes cure by the chemical reaction of the base resin and a curing agent. Polyesters, one-compone
36、nt polyur- ethanes, methacrylates, polysulfides, and silicones cure by the addition of a catalyst or release of a catalyst in- cluded in the formulation. The curing reaction of a monomer/curing agent is very temperature-dependent6 Lower temperatures ex- tend the curing time and higher temperatures s
37、horten the curing time. Although special adhesives are availa- ble that will cure at temperatures down to O F (-18 C), most adhesives will not effectively cure in a practical time at temperatures below 40 F (4 C). Catalytic curing is less temperature-dependent than the monomer/curing agent reaction,
38、 and the cure rate can be increased by the addition of an acelerator. The adhesive must cure quickly enough to obtain strength levels that can resist stresses that develop fi-om removal of support of the bonded composite, or fi-om temperature changes in the bonded composite; and fi-om exposure to mo
39、isture due to precipitation, tides, or other sources which could cause degradation. 2.1.3 Viscosi - Polymeric adhesives are available ., .I with viscosities ranging fi-om 15 centipoise (cps) to a paste-like consistency. The viscosity of the adhesive de- pends on the inherent viscosity of the base mo
40、nomers and curing agents, fiiers, and thixotroping agents. The viscosity of any adhesive can be lowered by raising its temperature. This can be achieved either by heating the adhesive itself or by heating the substrate. 2.1.4 Thixotropy - Very viscous adhesives are not necessarily thixotropic. When
41、thixotropic properties of an adhesive are desired, an adhesive must be chosen that has been manufactured to include thxotroping agents. Generally, high temperatures will lower the thixotropic characteristic of the adhesive and lower temperatures will increase the thixotropy, but is not af- fected to
42、 the same extent as viscosity by temperature.8 Adhesives are available that will stand in a bond line as thick as 1/4in. (6.4 mm) without external contain- ment. 2.1.5 Toxicity and safety - Most components of solvent-free adhesives prior to curing have some degree of toxicity and some are flammable.
43、 Toxicity and haz- ard potentials vary widely fi-om product to product. The manufacturers literature and Material Safety Data Sheet (MSDS) for each product should be consulted, and all cautions should be observed. In general, adhe- sives require the use of protective clothmg, good venti- lation, goo
44、d housekeeping, and personal cleanliness. 2.2 - Properties during cure 2.2.1 Gel - Cure of an adhesive is accompanied by an increase in viscosity and formation of a gel state be- fore full cure. In the gel state, the adhesive does not possess the physical or chemical properties it will ulti- mately
45、achieve. If the adhesive is stressed during cur- ing, irreversible damage can be done to the bond with the substrate or the adhesive itself, resulting in lower strength., 2.2.2 Exothermic reaction - The chemical reaction of curing is exothermic and can accelerate cure rate, re- sulting in the adhesi
46、ve reachmg the gel state at an ele- vated temperature. If this happens, internal stresses are induced in the bond when the adhesive cools to normal temperature. On a practical level, this condition occurs only in bond lines greater than 0.125 in. (3.2 mm) in thickness, because in narrow bond lines t
47、he heat dissipates into the substrates. 2.2.3 Shrinkage - All adhesives shrink when they cure. The addition of fillers to an adhesive system will reduce volumetric shnnkage but the inherent character- istics of a particular polymer s stem have by far the greatest influence on shrinkage. Volumetric s
48、hnnkage fi-om the uncured to the cured state varies fi-om as low as 2 percent for filled epoxy systems to over 20 percent for some unfilled polyester systems. Shnnkage works against good adhesion. It reduces the intimate contact between adhesive and substrate that is important for mechanical interlo
49、ck and attrac- tion of the adhesive molecules to the substrate surface; it also builds internal stress in the bond line.I2 17 POLYMER ADHESIVES 503.5R-5 2.3 - Properties of cured adhesive bond depends on: als. 2.3.1 Bond strength - The strength of an adhesive a. Adhesion of the adhesive to the substrate materi- 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 strength., In all bondindrepair applications, the surface of the hardened concrete must be sound and clean. Grease an
