The use of polymers in the building industry has continuously shifted to repair motors for both concrete and stone from the classical concrete crack injection. Repairing of timber structures, waterproof materials, and consolidation of masonry to are contributions of composite polymers. Utilization of pure polymers however resulted in inherent physical and chemical problems of incompatibility, relatively fewer durability periods, and mechanical malfunctioning.
Reliance on mineral oil as a cheap raw material for polymer production is also no longer a viable option considering fluctuations of oil prices in the world market. Composite polymers though provide construction materials that are not only durable but also sustainable. The use of such should be restricted to areas in which specific properties are required. Desirable synergic effects in the composites are achieved by combining polymers with classical materials under controlled conditions (Koleva and Boyadjiiski2005. pp. 9-13). Curing processes and a better understanding of materials behavior have improved due to the study of Admixtures. This has resulted in the development of modified concrete, motors, and grouts which are high-performing. Concrete- polymer composites (CPC) science is currently an invaluable component in the race to develop sustainable construction materials (Ohama, 2006. p.3).
Evaluation of the efficiency of a polymer application and creating the synergies when combining polymers with other materials is significant in the choice of polymers for usage. In general, therefore, the future of concrete-polymer composite is in technology and the ability to manage it.
Composition and structure, properties, and processing
Various concrete polymers composites have different characteristics depending on constituents’ materials and the controlled conditions under which the CPCs are made.
Polymer-modified concrete (or mortar)
Polymer modified concrete is also known as the motor is a popular admixture made up of styrene-butadiene rubber latex, poly (ethylene-vinyl acetate), poly (ethylene-vinyl acetate) and, polyacrylic ester emulsions. The composite polymer also contains re-dispersible polymer powders such as poly (vinyl acetate vinyl versatile-acrylic ester), poly (vinyl acetate-vinyl versatile), and poly (ethylene-vinyl acetate) powders which are additives to the cementitious mortar mixtures influencing the various desirable attributes (Mather et al. 2006. p. 2813).
Strengthening of existing reinforced concrete
Currently, beams or girders and slabs are strengthened using overlays that increase their thickness through troweling or shortcreting of the bottom surfaces by polymer-modified mortars. The troweling or shortcreting work of polymers is also used to retrofit existing reinforced concrete and shear walls.
Repairing of deteriorating reinforced concrete
This kind of concrete structure sometimes deteriorates, but still has reasonable time frames of usefulness. These can undergo cosmetic repairs which not only improve their aesthetic value but also reduce the rate of deterioration of the concrete with time. Developing effective materials which are effective together with the execution systems in civil structures is of significance in elevating the longevity of concrete structures. Some of the materials used to repair reinforced structures that are deteriorating are concrete impregnants to modify and improve the quality, coating materials that inhibit corrosion for bars, surface preparation materials, grouts in concrete cracks, patch materials, and coating materials for finishing and protection of the reinforced concrete (Koleva and Betchev, 2001).
Adhesives (Bonding) Agents for Exfoliation (Delamination) Prevention
Exfoliation prevention methods by use of pastes and polymer-modified mortars as adhesives with aramid, nylon, alkali-resistant glass fiber sheets, and polyethylene are used because of the advantage of being easy to apply on wet concrete substrates.
Polymer concrete (or mortar)
Additives such as thermosetting resins too are used for polymer mortars. Popular of these include thermosetting resins such unsaturated polyester, vinyl ester, polyurethane, epoxy, tar modified, and acrylic resins like polymethyl and glycerol methacrylate. In Japan, developments have been made on polymer concretes and mortars utilizing waste expanded polystyrene (EPS) solution-based binders for recycling. Resins containing 30% or less styrene and are used in polymer mortars and concretes due to environmental and ecological safety concerns. Developments have also been made on low-odor methacrylate binders for floor coatings and linings. Low-shrinkage UP resins are made through the usage of combined polymeric surfactant, vinyl, and steel fibers (Koliago and Struck, 1990). The product has neither shrinkage-reducing nor low-profile agents. Since mechanical properties of concrete polymer composite are dependent on thermal features, it is an aspect of resin development that is carefully observed.
The pavement of drainage is done using ultra-lightweight, porous EP concretes which are produced through a prepacked concrete procedure. There is also high demand for artificial polymeric marble products that use polymer pastes with aluminum and magnesium hydroxides used as flame-retarding fillers in these pastes. Major areas in which artificial marble products are applied are in kitchens, washstands, and bath fields. Presently unsaturated polyester concretes and mortars are utilized in both structural and nonstructural products (Cherian and Varghese, 2007.p.1462).
Application of accelerated curing
Autoclave curing is a technique that can be applied to SBR-modified concretes to manufacture precast products using slag. According to Cherian and Varghese, (2007. p. 1237), “a study to examine hardener-free epoxy resin as a polymeric admixture for the accelerated curing of cement concrete shows that the application of a 120ºC-autoclave curing or 90ºC–steam curing plus 120ºC–heat curing to hardener-free epoxy-modified mortars with polymer-cement ratios of 10 to 20% causes the concrete to develop about twice to three times higher flexural strength and about twice higher compressive strength than unmodified mortar (ordinary cement mortar)”.
Grouting open-graded asphalt concrete voids produce semi-flexible pavements for heavy-duty. This is done with polymer-modified slurries producing excellent resistance to abrasion, oil, and colorability. Application of the composite is in highway intersections, roads with heavy duty traffic, bus stops, airport runways, and parking lots among other areas that demand the above features.
Polymer-modified mortar and concrete have developed wide applications throughout the world in the construction of various civil structures. This has initiated the need development of standardization measures to ensure the quality of the products that find their way into the market. Standardization measures focus on testing and evaluation procedures applied to polymers before they are released into the market as the composites should exhibit specific characteristics for particular jobs depending on the suitable conditions for real service. The result is various fillers, of varying chemical compositions and characteristics. Adsorptional and adhesional interaction property with the polymer binder is determined by the chemical nature of fillers (Ohama, 2006).
The synergic effect depicted in concrete polymer composite provides it with an excellent opportunity to improve and be applicable in a wider range of innovative purposes. In the usage of polymers guarantee of better performance and sustainability are important in the choice of material. This together with advanced construction and repairing techniques has contributed to their widespread replacement of classical organic building materials. Additives in polymer composites help in increasing their strengths against bending and compression. The high cost of processing, difficulties in application, and cumbersomeness of manufacturing polymer-impregnated concrete (mortar) hinder usage in many countries throughout the world. As technology advances, however, more sustainable quality CPSs are developed.
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Koleva, M. Betchev, C. (2001).Viscosimetric Investigations of Unsaturated polyester resin – High impact Polystyrene Blends. Journal of Theoretical and Applied Mechanics, 31 (4).
Koleva, M. Boyadjiiski,G. (2005). Influence of the mixing conditions on the physicomechanical properties of the polymer system NPES/UPS, J. Techn. Univ.– Gaborovo. 32, 9–13.
Koliago, G. Struck, W.A. (1990) Materials based on unsaturatedpolyesters, Minsk: Nauka itechnika.
Mather et al. (2006) Modification of bisphenol. A based bismaleimide resin (BPA-BMI) with an allyl– terminated hyperbranched polyimide (AT-PAEKI), Polymer, 47 (8), 2813–2821.
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