Thermal volume changes of the mineral–water system in low-porosity clay soils

TLDR

In low‑porosity clays, the skeleton can compress or expand depending on effective pressure. The study employed drained heating and isotropic loading tests at various effective stresses and temperatures on low‑porosity clays. The experiments revealed that adsorbed water in low‑porosity clays expands much less with temperature than free water, affecting overall thermal strains. Keywords include nuclear waste isolation, clay, low porosity, thermal strain, and adsorbed water.

Abstract

The effect of temperature on the volumetric strains of the clay skeleton and clay – water system has been examined experimentally. Heating tests at (various) constant effective stress and isotropic loading tests at (various) constant temperatures were performed on low-porosity clays under drained conditions. The results indicate that the thermal expansion of adsorbed water in these clays is significantly lower than that of free water. Depending on the effective pressure, the clay skeleton may undergo either compression or expansion. Key words: nuclear waste isolation, clay, low porosity, thermal strain, adsorbed water.