Investigation of ageing of alumina cement based mixtures

Abstract

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 the cement and other components of cementitious mixtures with moisture as well as with CO2 from the atmosphere. In this work, the ageing behavior of calcium aluminate cement and its mixtures with additives of microsilica, fluidized catalytic cracking catalyst waste (FCCC) and ground quartz sand was investigated. The ageing was performed by storing cement and its mixtures in a climatic chamber for 7 and 14 days at 95% relative humidity and 20±1 ºC temperature. Upon applying thermal analysis, XRD analysis as well as scanning electron microscopy, it was found that during ageing of cement and its mixtures, hydration of the cement minerals along with carbonation take place. The quantities of the products formed during ageing and their crystallinity depend on the nature of the additives and the duration of ageing. Upon applying the method of calorimetric analysis, the influence of ageing on the kinetics of hydration of cement and as well of its mixtures with the additives used in the work has been established.