The possibility of thermal activation of bentonitic clays: impact of temperature

Abstract

This article deals with the possibility of thermal activation of bentonitic clays. Specifically, the impact of temperature on the overall performance of two varying thermally activated bentonitic clays was investigated and compared with conventional kaolinitic clay. Firstly, the raw materials were characterized; their phase composition, granulometry and thermal analysis were measured. Then studied clays were fired at different temperatures from 500°C to 650°C. Afterwards, the overall performance of thermally activated clays was assessed through the view of their characterization as well as their applicability as Portland cement replacement. The main outcomes were as follows: Bentonites were more susceptible to agglomeration compared to kaolinite. They showed higher mass changes during the heat treatment, but lower increases in specific surface areas. On the other hand, for proper thermal activation, they needed a lower temperature. 600°C seemed to be optimal for the bentonitic clays, while for kaolinite the better results were observed in the case of 650°C. Moreover, thermally activated bentonites reached comparable mechanical strengths of blended cement pastes as the one with kaolinitic clay.