Magnesium sulfate attack on hardened blended cement pastes under different circumstances

Abstract

This paper describes the sulfate resistance of some hardened blended Portland cement pastes. The blending materials used were silica fume (SF), slag, and calcium carbonate (CaCO 3, CC̄). The blended cement pastes were prepared by using W/S ratio of 0.3. The effects of immersion in 10% MgSO 4 solution under different conditions (room temperature, 60 °C, and drying–immersion cycles at 60 °C) on the compressive strength of the various hardened blended cement pastes were studied. Slag and CC̄ improve the sulfate resistance of ordinary Portland cement (OPC) paste. Mass change of the different mixes immersed in sulfate solution at 60 °C with drying–immersion cycles was determined. The drying–immersion cyclic process at 60 °C accelerates sulfate attacks. This process can be considered an accelerated method to evaluate sulfate resistance of hardened cement pastes, mortars, and concretes.