Hydration of C₄AF in the presence of artificial CaSO₄ and lime

Abstract

The ferrite phase consists of about 8-13 wt% portland cement. This phase has received little attention with regard to its hydration. The aim of present investigation is to synthesize the ferrite phase and study the rate of hydration in the presence of CaSO₄ and CaO up to 28-days in suspension. This study is followed by the determination of the free lime as well as

combined water con tents and the hydration products by the XRD analysis. The results revealed that whatever the amount of CaSO₄ the monosulphate AF_m was the only phase formed from 6 h up to 28-days and the ettringite AF_t was not formed. In the presence of 1 mol CaSO₄ and 2 mol CaO, the monosulphate AF_m with carboaluminate was the dominant phase at 28-days. When the amount of CaSO₄ was increased to 3 mol with the same amount of lime the hydration was retarded in comparison with that containing 1 mol of CaSO₄. Very small amount of sulphoaluminate ferrite hydrate was formed with residual reactants such as C₄AF,CaSO₄ and Ca(OH)₂.