Polymer impregnated concrete initiators

The technology of concrete soaking with monomeric substance and subsequent m situ" polymerization is relatively new. According to Worn [171], it was initiated by Steinberg in 1968. Beside of the polymer impregnated concretes, there are also the polymer concretes (resin concretes) without cement and the polymer-eement concretes in the latter case cement is mixed with monomer and water to produce the concrete mixture . This question will be discussed in Chap. 10. 

Polymer Impregnated Concrete (PIC) obtained with hardened ordinary concretes, which are dried and then permeated with monomers of sufficient viscosity by vacuum or monomer displacement and pressure. Then, in-situ polymerization of the monomer is carried on by radiation, heating or chemical initiation. As an effect, a large part of the voids and pores is filled with polymer, which forms a continuous reinforcing network. 

Polymerization of monomer-impregnated concrete was initially carried out with 60Co gamma radiation. A principal advantage of using radiation is that free radical chain reactions can be induced at ambient temperature. This limits vaporization loss and may produce a better concrete-polymer bond. The disadvantages are the dose requirements and the relatively high initial investment required for the radiation source and facility. 

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. 

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