Hydration of calcium aluminate cement with calcium sulfate and supplementary cementitious materials

The main products of the building chemistry industry are ternary blends composed of Portland cement (PC), calcium aluminate cement and calcium sulfate. In this study, low levels of PC were replaced by supplementary cementitious materials (SCM). The selected SCM are slag and limestone. The study focused on the such systems with limestone or slag and variable calcium sulfate. The hydration kinetics and the phase evolution were followed to understand the behaviour of the different systems with variable calcium sulfate and SCM amounts. This is important to qualify and eventually quantify the reaction of the SCM used in these systems. The reaction of SCM is highly dependent on the calcium sulfate content in the system. An increase of calcium sulfate is followed by a decrease of the reaction of SCM. The reaction of limestone leads to the formation of hemicarboaluminate and monocarboaluminate while the reaction of slag leads to the formation of strätlingite. Experimental results were compared to thermodynamic modelling to better understand the synergies between CAC-calcium sulfate and SCM

Author: J. Bizzozero, K.L. Scrivener

Section: Science and production

Keywords: hydration, microstructure, calcium aluminate cement, slag, limestone