The introduction of p-vinyl sulfonic acid into Portland cement modifies the quality and performance of the material. It was found that the ionomer decreases the porosity and increases the fluidity of the material. Cracking after stress was found to be higher for the polymer-cement and was observed mainly in the cement-aggregate interface, while the cracks in the blanks appeared mostly within the cementitious phase. The composite cubes withstood 7 days immersion in conc. HCl far better than those of the blank.