Physico-chemical studies on hydrothermal characteristics of calcite-rich clays

ABSTRACT

Marl-clay deposits containing 30% CaCO3 from Sinai, Egypt, were calcined at different temperatures between 800C to 950C for 30 min. The processed briquettes from these powders were hydrothermally treated at 202C [16 atm] for 4 hours. The evaluation and assessment of the treated specimens were achieved through the determination of their physical properties and the phases developed by XRD, IR- spectroscopy, SEM and chemical analysis. The thermochemistry of these phases were followed using DSC and TG technique. A correlation between the determined properties and the developed phases were also discussed. The results encountered in this investigation indicated that the physical properties of the hydrothermally treated bodies are improved with increasing the precalcination temperature. Also, the data encourage the utilization of this technique [autoclaving] in production of building units from lime-rich clays as is followed in sand lime bricks industry without any additives