Abstract

In this study, kaolinite and bentonite were investigated for the effect of thermal treatment on particle size, as well as water content, specific gravity, plasticity, activity index, swelling and compression index and strength properties. At first, kaolinite and bentonite were characterized using XRD and TG standard methods. All sieved samples were subsequently heated to various temperatures (100, 200, 400, 500 and 600°C respectively), and kept for 24 h at the maximum temperature. Odometer cells were used to describe the compressibility properties (loading and unloading) of the compacted-treated samples. Triaxial compression tests were carried out to determine thermal treatment effects on the strength parameters of all samples. It was found that kaolinite becomes non-plastic at 400°C and bentonite at 500°C. Grain size growth with increasing thermal treatment plays indeed a major role. Thermal treated kaolinite and bentonite up to 400°C drastically reduces their swelling behavior. Strong correlations between the angle of shearing resistance and thermal treatment of both materials and correlation coefficients have been demonstrated. The results showed that kaolinite and bentonite can be used as good stabilization materials if they are thermal treated; kaolinite up to 400°C and bentonite up to 500°C.

Key words: Kaolinite, bentonite, thermal treatment, index properties, scanning electron microphotograph.