Polymer impregnated concrete modifiers

Keywords Concrete-polymer composites. Polymer-modified concrete. Polymer concrete. Polymer-impregnated concrete. Principles of process technology. Research and development. Standardization work. Sustainable concrete-polymer composites. History, The recent and future trends. 

Polymers. The purpose of adding polymers to the concrete matrix is to improve the characteristics of the fresh concrete (such as workability) and also to enhance the hardened properties such as flexural strength, modulus of elasticity and adhesive performance [8]. The incorporation of polymers into concrete may be in the form of polymer modified concrete (PMC), polymer impregnated concrete (PIC) or as polymer concrete (PC) [9], For this project, the objective was to develop an ultra-lightweight concrete material using Portland cement as the main binder modified with a suitable polymer - thus a PMC application. The polymer modifiers selected for the development of the ultra-lightweight thin filmed material were a commercially available SBR latex as well as a readily available acrylic polymer. 

In this type of system, a matrix with a more or less continuous pore system is filled with a second component. The pore system is, however, fixed during the formation of the matrix itself. Thus one might expect some differences between polymer-impregnated concretes and the latex-modified concretes discussed above for example, the latter are inherently more porous because porosity will always develop during curing, regardless of the presence of polymer. In both cases, however, the cement and polymer phases appear to form continuous and intertwined networks. 

As an additive to cement and reinforcer to concrete Polymer modified concrete (PMC), polymer concrete (PC), polymer impregnated concrete (PIC), fibre-reinforced plastic (ERP) rebars... 

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. 

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. 

Combinations with polymers can be obtained by impregnation of the hardened composite (polymer impregnated concrete - PIC) or with a polymer latex which is added during mixing (latex modified cement - LMC) [137]. Both types of polymer incorporation would be expected to increase the matrix strength and the fibre-matrix bond. However, their influence on the other matrix properties is quite different. In PIC, the matrix has a higher modulus of elasticity and becomes more brittle, while in LMC the matrix will be more ductile with a lower modulus of elasticity. 

PIC is a precast and cured portland cement concrete that has been impregnated with a monomer that is subsequently polymerized in situ. This type of cement composite is the most developed of polymer-concrete products. PCC, on the other hand, is a modified concrete in which a part (10%-15% by weight) of the cement binder is replaced by a synthetic organic polymer. It is produced by incorporating a monomer, prepolymer-monomer mixture, or a dispersed polymer (latex) into a cement-concrete mix. To effect the polymerization of the monomer or prepolymer-monomer, a catalyst (initiator) is added to the mixture. The process technology used is very similar to that of conventional concrete. So, unlike PIC which has to be used as a precast structure, PCC can be cast-in-place in field applications. PC can be described as a composite that contains polymer as a binder instead of the conventional portland cement. 

Figure 11.11. Compressive stress-strain curves for concrete impregnated with poly(methyl methacrylate). Polymer loading MMAl > MMA2 > MM A3. Specimen L25 is a latex-modified concrete. (Dahl-Jorgensen and Chen, 1973.)...

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