STRESS-STRAIN PROPERTIES OF POLYMER MODIFIED CONCRETE

This experiment was designed to investigate some of the structural properties of polymer modified concrete. Three by six in. (7.6x15.2 cm) cylindrical specimens were prepared and tested in simple compression and split tension to obtain the entire stress-strain relationship for this concrete. For the polymer-impregnated concrete (PIC), the monomer methyl methacrylate was used. Polymerization was done by the thermal-catalytic method with benzoyl peroxide and azobisisobutyronitrile to initiate polymerization. The concrete used in the experiment was dense and of high strength. With the use of 3 percent benzoyl peroxide complete polymerization was not achieved, leaving a central core in the specimens containing unpolymerized monomer. However, 0.5 percent azobisisobutyronitrile gave full polymerization. The results obtained for PIC are comparable and confirm the improvements in properties of concrete observed by many researchers in this field. For the Polymer Cement Concrete (PCC), the monomer diacetone diacrylamide was mixed in the fresh concrete and followed by polymerization. The specimens responded negatively both to heat treatment and moisture curing and it was apparent that the polymerization and hydration processes react unfavorably and are incompatible simultaneously. A latex product named Sarabond was also used. This is a polymer dispersed in water and no polymerization is required. The increase in strength was only modest compared to what was obtained for PIC. /ACI/