Studies on the changes in compressive strength, split tensile strength, acid resistance, and percentage water absorption are reported for systems of plaster of paris and plaster of paris blends upon impregnation with monomer (MMA) followed by polymerization (in situ), as well as for systems of plaster of paris-epoxy resins with subsequent monomer impregnation.

Cured precast portland cement mortars were impregnated with the monomer‐initiator mixture (mmA or styrene or both and AIBN or benzoyl peroxide), polymerized, and cured and the change in compressive strength, and, in some cases, the change in tensile strength were studied. The effect of impregnation on the compressive strength and environmental stress (freezing and thawing, acid resistance, weathering effect, and sea water resistance) were studied. It was found that the incorporation of polymer into the pores of the already‐set cement increased the compressive strength even after freezing and thawing, acid resistance, and sea water resistance and weathering. Among the monomers used. mmA was found to give the best properties to the mortar. Fly ash, when added in small amounts, increased the compressive strength. © 1996 John Wiley & Sons, Inc.

SYNOPSISCured precast portland cement mortars were impregnated with the monomer-initiator mixture (mmA or styrene or both and AIBN or benzoyl peroxide), polymerized, and cured and the change in compressive strength, and, in some cases, the change in tensile strength were studied. The effect of impregnation on the compressive strength and environmental stress (freezing and thawing, acid resistance, weathering effect, and sea water resistance) were studied. It was found that the incorporation of polymer into the pores of the already-set cement increased the compressive strength even after freezing and thawing, acid resistance, and sea water resistance and weathering. Among the monomers used, mmA was found to give the best properties to the mortar. Fly ash, when added in small amounts, increased the compressive strength. 0 1996 John Wiley & Sons, Inc. I NTRO DU CTI 0 NCement concrete is one of the most versatile structural materials today. Low cost, easy moldability to complex forms, and versatility have made cement concrete and other cement-based composites very popular. They are used for a wide range of applications including irrigation and industrial, residential, institutional, transportation, and marine structures. Nevertheless, cement composites suffer from several shortcomings' such as low compressive, tensile, and flexural strengths, poor bonding with already-set materials, higher porosity and permeability, poor resistance to acids and other aggressive chemicals, low strength-to-weight ratio, and poor elastic modulus. This results in the deterioration of seaside structures, water seepage in large water-retaining structures, and deterioration of concrete as a result of chemical pollution of the atmosphere due to growing industrial activities.Efforts have been made to improve the properties of conventional concrete with the use of polymer~.'-~ Over the last 30 years, a new family of composites called polymer concrete composites which are superior to conventional concrete was developed by modifying the cement composites with polymers