Effect of high temperature on some physical properties of bentonite from Barmer, Rajasthan, India

Globally bentoite clay has been proposed as an engineered barrier material for safe underground disposal of high-level nuclear waste. Clay has many favorable properties such as high liquid limit, and plastic limit along with other properties which make it the most suitable for this application. In the present study, an attempt has been made to study the behavior of Barmer bentonite under the influence of high temperatures up to 120°C. Properties of barmer bentonite namely, liquid limit, plastic limit, and maximum dry density have been determined after thermal treatment at 25 ° C, 60 ° C, 80 ° C, 100 ° C and 120 ° C. The extensive experimental results indicate that liquid limit and plastic limit show a decreasing trend while maximum dry density increases with an increase in temperature. Liquid limit and plastic limit decrease up to 12% and 11% respectively when the temperature reaches up to 120 ° C. Maximum dry density increases by 10% due to thermal treatment and optimum water content decreases by up to 4%. Statistical analysis has been carried out to obtain the correlation between temperature and physical properties of Barmer bentonite such as liquid limit, plastic limit, maximum dry density, and optimum water content. The XRD analysis of Barmer bentonite at room temperature and 120 ° C shows very small variation in mineralogical composition. Whereas, interlayer distance has been measured and found to be decreasing with an increase in temperature. Further, a comparative analysis shows that the measured properties of studied Barmer bentonite lie in the range of previously measured values of other types of bentonite across the globe.