Mechanical performances of super sulfated cements
Résumé
Tested super sulfated cements (SSC) are composed of various amounts of ground granulated blast furnace slag, gypsum or activated gypsum and Portland cement. Our initial results on the optimization of the composition and of the curing conditions of such cements are presented herein. Tests are conducted on the basis of standard mortar with two different water/binder ratios according to old and new standards for SSC. Four types of curing are used: laboratory, wet room and immersion at 20°C or 40°C. Mechanical performances are assessed at 2, 7, 28, 60 and 90 days on standard mortar samples (binder/sand mass ratio = 1/3). This study shows that thanks to an optimization of the Portland cement content, it is possible to obtain super sulfated cement with a strength class 32.5N (for samples immersed in water at 20°C). These samples are always in conformity with the new European standard. For a given SSC formulation, it is noticeable that the origin of the calcium sulfate addition affects the setting and hardening phenomena . The use of heat-activated gypsum as a sulfate activator appears preferable.