Thermo-mechanical behaviour of a compacted swelling clay

TL;DR

This study investigates the thermo-mechanical behavior of compacted swelling clay under various conditions, revealing how temperature, suction, and pressure influence its deformation and yield properties, relevant for nuclear waste containment.

Contribution

It provides new experimental data on the combined effects of temperature, suction, and pressure on swelling clay's behavior, including thermal hardening phenomena.

Findings

Heating causes swelling or contraction depending on conditions

Lower suction reduces yield pressure and increases compressibility

Temperature has minimal effect on compressibility parameters

Abstract

Compacted unsaturated swelling clay is often considered as a possible buffer material for deep nuclear waste disposal. An isotropic cell permitting simultaneous control of suction, temperature and pressure was used to study the thermo-mechanical behaviour of this clay. Tests were performed at total suctions ranging from 9 to 110 MPa, temperature from 25 to 80 degrees C, isotropic pressure from 0.1 to 60 MPa. It was observed that heating at constant suction and pressure induces either swelling or contraction. The results from compression tests at constant suction and temperature evidenced that at lower suction, the yield pressure was lower, the elastic compressibility parameter and the plastic compressibility parameter were higher. On the other hand, at a similar suction, the yield pressure was slightly influenced by the temperature; and the compressibility parameters were insensitive to temperature changes. The thermal hardening phenomenon was equally evidenced by following a thermo-mechanical path of loading-heating-cooling-reloading.