Polymer modified cement concrete

The earliest indication of the use of polymers in concrete was apparently in 1909, in USA when a patent for such use was granted to Baekeland and in 1922 in France and in 1923 in UK [38]. Polymers can be added by three different methods into normal concrete, leading to polymer impregnated concrete (PIC), polymer modified cement concrete (PCC) and polymer concrete. 

Two materials being widely used for the repair and renovation of damaged concrete are Polymer Concretes (PCs) and Polymer Modified Cement Concretes (PMCCs). These materials are very different in both composition and behaviour. PCs are highly filled polymers (e.g.epoxide resins) and contain no hydraulic cement-water phase. PMCCs on the other hand contain up to about 20% of latex (e.g. Styrene/Butadiene resin ... 

Sprayed or trowelled concrete with or without admixtures or bonding aids. Polymer Modified Cement Concrete. Epoxide Resin Mortar. 

Today, polymer modified cement concrete (PCC) mortars, which can be applied by... 

Architectural Institute of Japan (AIJ) Recommendation and Guideline (Japan) PMC, PC and PIC Recommendation for practice of concrete-polymer composites Recommendation for practice of survey, diagnosis and repair for deterioration of reinforce concrete structures Guideline for polymer-modified cement waterproofing membrane work... 

Polymer-modified cement mixes are produced by mixing together an inorganic cement (most commordy Portland cement), water, and a dispersion of an organic polymer. If concrete aggregate or sand is also added, polymer-modified concrete or mortar mixes are obtained. Compared with similar polymer-free mixes, the addition of water may be reduced or omitted entirely, as the polymeric dispersion supphes part or all of the water needed for hydration and for obtaining adequate rheology of the mix. 

OlUtrault-Fichet, R. et al. (1998) Microstructural aspects in a polymer-modified cement. Cement and Concrete Research 28,1687—1693. 

Concretes with polymers are generally classified into three categories as polymer concrete (PC), polymer Portland cement concrete (PPCC), which is also known as latex-modified concrete (LMC) and polymer-impregnated concrete (PIC) according to their process technologies. 

Kruger, T. (1991) Mechanical behaviour of polymer modified cement mortars under complex stress states, in Proc. Int. Symp. Concrete Polymer Composites, H. Schorn and M. Middel, eds, Bochum, Germany pp. 135-46. 

Epoxy resin has superior properties such as high adhesion and anticorrosion, and has widely been used as adhesives and anticorrosives in the construction industry in the world. Provided the incorporation of the epoxy resin into cement mortar can give its superior properties to the mortar, it is possible to produce a highly polymer-modified cement mortar. The first patent of an epoxy-modified cement system was taken by Donnelly in 1965 [1]. Since the patent, 30 or more papers on the epoxy resin modification of the cement mortar and concrete have already been published [2]. Most epoxy resin-based cement modifiers dealt with in the papers are specially compounded by the manufacturers, and the procedures for mixing them to fresh mortar and... 

Of the several types of the polymer-modified mortars and concretes used for various construction applications, latex-modified mortar and concrete are by far the most widely used materials. Latex-modified mortar and concrete are prepared by mixing a latex, either in a dispersed liquid or as a redispersible powder form with fresh cement mortar and concrete mixtures. The polymers are usually added to the mixing water just as other chemical admixtures, at a dosage of 5-20% by weight of cement. Polymer latexes are stable dispersions of very small (0.05-5 pm in diameter) polymer particles in water and are produced by emulsion polymerization. Natural rubber latex and epoxy latex are exceptions in that the former is tapped from rubber trees and the latter is produced by emulsifying an epoxy resin in water by the use of surfactants [87]. 

Comparing the cost of the various concretes shows that at times of low sulfur prices, sulfur concrete can even compete with high-strength cement concrete. The costs of polymer concrete per cubic meter are quite enormous. Yet the substantially higher production costs of polymer concrete have not been considered yet. The prices used for this comparison are based on European conditions. To assess the sulfur concrete costs we used two extreme sulfur prices which had to be paid,in the last years. The total costs of DCP-modified sulfur concrete rose only negligibly with the addition of this plasticizer (Table IX). 

Polymer concretes show excellent mechanical properties and chemical resistance compared with conventional cement concretes. Polymer concretes can be cured quickly by the use of curing agents. Thus, the applications of polymer concretes are being increased. One of the popular polymers for polymer concretes is unsaturated polyester (UPE) resin. The properties of UPE resin can be modified by changing its molecular features. For the synthesis of the resin, phthalic anhydride or isophthalic acid as well as maleic anhydride can be employed to modify the mechanical properties or hydrothermal resistance. Terephthalic acid which is also used for the synthesis of poly ethylene terephthalate (PET) enhances the thermal resistance of the cured UPE resin. However, the synthesis of unsaturated polyester resin from terephthalic acid is difficult. One method to synthesize unsaturated polyester from terephthalic acid is the use of recycled PET. 

Polymer modified lightweight cement mortar (PLCM) with plastics waste as aggregate is widely used as substrate mortar layer on the reinforced concrete wall for external ceramic wall tile installations instead of the ordinary cement mortar conventionally used. The reasons that this mortar is popularly used in building site are it s own lightweight and excellent workability for troweling. 

Reinforced concrete wall 2 Polymer modified lightweight cement mortar... 

Polymer-modified mortar and concrete are prepared by mixing either a polymer or monomer in a dispersed, powdery, or liquid form with fresh cement mortar and concrete mbctures, and subs uently curing, and if necessary, the monomer contained in the mortar or conoete is polymerized in situ. The polymers and monomers used as cement modifiers are shown in Fig. 2.1. 

Several types of polymer-modified mortars and concretes, i.e., latex-redispersible polymer powder-, water-soluble polymer-, liquid resin-, and monomer-modified mortars and concretes, are produced by using the polymers and monomers shown in Fig. 2.1. Of th, the latex-modified mortar and concrete are by far the most widely used cement modifiers. 

Although polymers and monomers in any form such as latexes, water-soluble polymers, liquid resins, and monomers are used in cement composites such as mortar and concrete, it is very important that both cement hydration and polymer phase formation (coalescence of polymer particles and the polymerization of monomers) proceed well to yidd a monolithic matrix phase widi a network structure in which the hydrated cement phase and polymer phase interpenetrate. In the polymer-modified mortar and concrete structures, aggregates are bound by such a co-matrbc phase, resulting in the superior properties of polymer-modified mortar and conoete compared to conventional. 

In the modification with water-soluble polymers such as cellulose derivatives and polyvinyl alcohol, small amounts of the polymers are added as powders or aqueous solutions to cement mortar and concrete during mixing. Such a modification mainly improves their workability because of the surface activity of the water-soluble polymers, and prevents the dryout phenomena (explained in Ch. 4, Sec. 3.1, Water Retention). The prevention of the dry-out is interpreted in terms of an increase in the viscosity of the water phase in the modified cement mortar and concrete and a sealing effect due to the formation of very thin and water-impervious film in them. In general, the water-soluble polymers hardly contribute to an improvement in the strength of the modified systems. 

When the coloring of latex-modified mortar and concrete is required, alkali-resistant, weatherproof pigments are used. Furthermore, it is important that the pigments do not obstruct the stability of polymer latexes and the hydration of cements. Alkali-resistant glass, steel, polyamide, polypropylene, polyvinyl alcohol (poval), aramid and carbon fibers are employed as mixable reinforcements. Reinforcing bars for ordinary cement concrete are also used for the reinforcement of the latex-modified concrete. 

Ohama, Y., Miyake, T., and Nishimura, M., Effect of Polymer-Cement Ratio on Fresh Polymer-Modified Concrete (in Japanese), Reports of Annual Meeting 1980, pp. 239-240, Architectural Institute of Japan (Sept. 1980)... 

Ohama, Y., Demura, K., Nagao, H., and Ogi, T., Adhesion of Polymer- Modified Mortars to Ordinary Cement Mortar by Different Test Adhesion between Polymers and Concrete Bonding,... 

Kuhlmann, A. L., Using Styiene-Butadiene Latex as a Modifier to Concrete for Bridge Deck and Parking Garage Overlays, Polymer-Modified Hydraulic-Cement Mixtures, STP-1176, pp. 125-140, American Society for Testing and Materials, Philadelphia (1993)... 

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