Influence of activation temperature of kaolinite-based clay wastes on pozzolanic activity and kinetic parameters

It is well known that the transformation of some clay minerals into pozzolanic materials for the manufacture of Portland cements depends on the activation conditions. In the current paper, a study was carried out to evaluate the effect of activation temperature in the range of 500–700°C on the characteristics of thermally activated clay wastes (ACWs). Different chemical, morphological, mineralogical and pozzolanic characteristics as well as kinetic parameter determinations were analysed in order to provide a complete study of the activated products and the viability of their use in the manufacture of blended cements. The results obtained showed that activation temperature plays a special role in the mineralogy of ACWs as well as their pozzolanic behaviour. Mineralogically, the ACWs were essentially formed from calcite and talc; kaolinite and chlorite were also identified depending on activation conditions. The values of the kinetic parameters indicated different pozzolanic activity of the ACWs, mainly over the short term.