Physical properties of low cement castable containing 22 wt.% Al2O3-rich MgO-Al2O3 spinel and 1.7 wt.% CaO with addition of polyacrylates, castament FS20, TPP and citric acid were investigated. Results showed castables including castament FS20 have higher flow values and better final properties comparing with castables including Darvan 7S and TPP. Also in this study we investigated the effect of addition of microsilica up to 4 wt.% on the properties of alumina-spinel castables. Microsilica is the finest particles in the system and due to suitable distribution of microsilica among other particle the open porosity reduced and mechanical strength increased. Slag penetrations resistance increased with increasing microsilica addition by forming a densification layer right behind the hot face of castables in service.
refractory castables; microsilica; alumina-spinel
