Porosity and compressive strength of cement paste in sulphate solution

Abstract

Plain portland cement paste of low w/c ratio was immersed in high to very high concentrations of sodium or magnesium sulphates. Compressive strength development was monitored up to a period exceeding two years. The pore size distribution characteristics which developed up to one year of immersion were monitored. Little effect on the compressive strength was observed after long time of immersion. The pore size distribution was generally characterised by a decrease in the volume of pores whose diameters are larger than 150 nm and an increase in the volume of pores of smaller diameters. An interpretation of the developments in porosity and strength of the hardened paste is presented.