Investigation of ageing of alumina cement-based mixtures using thermal analysis and calorimetry

The shelf life of cement and cement-based dry mixtures is often determined by ageing of such materials. The ageing is the result of interactions between cement and other components of cementitious mixtures with moisture as well as with CO 2 from the atmosphere. In this work, the ageing behaviour of calcium aluminate cement and its mixtures with additives of microsilica, fluidized catalytic cracking catalyst waste and ground quartz sand were investigated. The ageing was achieved by storing cement and its mixtures in a climatic chamber for 7 and 14 days at 95% relative humidity and 20 ± 1 °C temperature. Applying thermal analysis, XRD analysis as well as scanning electronic microscopy, it was established that hydration of the cement minerals takes place along with carbonation during the ageing process of cement and its mixtures. The quantities of the products formed during ageing and their crystallinity depend on the nature of additives and the duration of ageing. When applying the method of calorimetric analysis, the influence of ageing on the kinetics of hydration of cement and as well as of its mixtures with the additives used in the work has been established.