Sulfoaluminate cement behaviours in carbon dioxide, warm and moist environments

Abstract

Calcium sulfoaluminate cements are hydraulic binders characterised by fast setting and hardening, moderate shrinkage and high resistance to aggressive agents. Their manufacture requires less energy and generates less carbon dioxide than traditional Portland cement; however, their long-term durability, mechanical properties and dimensional stability in different environments are not much studied. The aim of this work is to compare the properties of calcium sulfoaluminate cement mortars at three different water to cement (w/c) ratios, 0·45, 0·58 and 0·78, with a standard CEM I Portland cement mortar. The study was performed during 3 months when the samples were kept in four different environments: ambient air at 20°C and 65% relative humidity; dry air at 45°C and 35% relative humidity; water at 45°C; and saturated carbon dioxide at 20°C. Results show a great sensitivity of the calcium sulfoaluminate mortars to carbonation, with various consequences on their mechanical properties and dimensional stability. The consequences are much more moderate, however, when w/c ratio is low.