Supercritical carbonation of calcium aluminate cement

The microstructural changes occurring during supercritical carbonation (scCO(2)) of calcium aluminate cement (CAC) and changes to its strength have been investigated. Cylindrical specimens of CAC cured at different temperatures were prepared and then subjected to scCO(2). It is shown that CAC carbonation in supercritical conditions is accelerated with a positive effect on the compressive strength. Due to the SCCO2 treatment, both conversion and alkaline hydrolysis are avoided. The best behaviour of the studied specimens was attained for samples cured at 25 degrees C. The residual compounds after the ScCO2 process, i.e. monocalcium. aluminate, calcium carbonate and aluminium hydroxide are durable in normal ambient conditions. Complete carbonation of CAC is particularly important for the reinforcement of CAC with polymer fibres to improve its mechanical strength. (C) 2008 Elsevier Ltd. All rights reserved.