Thermo-Mechanical Behavior of Bentonite at High Temperatures: Experimental Evidence and Constitutive Modeling

Abstract:

Bentonite-based materials are widely considered for engineered barriers in deep geological repositories for radioactive waste. Understanding their thermo-hydro-mechanical (THM) behavior at elevated temperatures is essential for assessing their long-term performance.

This seminar presents recent experimental and constitutive modeling investigations into the behavior of saturated bentonite at temperatures approaching 200°C. Laboratory tests conducted using specially developed high-temperature equipment provide insights into thermal volume changes, swelling pressure, compressibility, and water exchange under controlled mechanical and hydraulic conditions.

The results reveal notable changes in bentonite behavior at elevated temperatures, highlighting complex interactions between thermal, hydraulic, and mechanical processes. These findings are interpreted through a constitutive modeling framework incorporating an additional thermally activated plastic mechanism. The implications for predicting bentonite behavior under extreme thermal conditions and for the performance of engineered barriers are discussed.

Short bio:

Marcelo Sánchez is the Fred J. Benson Chair Professor in the Zachry Department of Civil and Environmental Engineering at Texas A&M University, USA. He obtained his Ph.D. from the Universitat Politècnica de Catalunya (UPC), Barcelona, Spain, in 2004. His research focuses on advanced geomechanics, particularly coupled thermal, hydraulic, mechanical, and chemical processes in geomaterials, with applications in energy and environmental geotechnics. He has authored more than 150 peer-reviewed publications and received several awards, including the George Stephenson Medal from the Institution of Civil Engineers (UK) in 2012. He is the founder and former Chair of the ISSMGE Technical Committee TC308 on Energy Geotechnics and has served as Chair of the ISSMGE Technical Oversight Committee.