Studies on the influence of aluminosilicate additive on initiation steps of high calcium aluminate cement hydration

Abstract

Aluminate cements are applied mainly in fire-resistant concretes. The use of aluminate cements in construction materials is problematic (and sometimes even banned) because of conversion of aluminates, taking place slowly in time. The effect of such conversion is the increase of porosity and reduction of material’s strength. There is an opinion that using particular additives the conversion of aluminates can be prevented or significantly slowed. The aim of this work is to demonstrate the influence of addition of spent aluminosilicate catalyst on early hydration (up to 28th day) of white high calcium aluminate cement. Two kinds of the additive were used: a raw material and a thermal treated one. Calorimetry, thermal analysis and SEM observations were used as investigation methods. EXO temperature and setting time were also measured. It was proved that the spent catalyst influences early cement hydration and microstructure of hardened material.