Effect of Temperature on the Compressibility Behavior of Glass Fiber-bentonite Mixture

Abstract

In line with the global need for energy, various renewable and clean energy sources have become increasingly popular. Heat piles, buried high-voltage cables, and high-level nuclear waste (HLW) storage areas are examples of energy structures. Since these energy structures emit high temperatures and increase the temperature of the surrounding soil, investigating and improving the thermo-hydro-mechanical behavior of soils under high temperatures has become essential. Bentonite is a clay with high montmorillonite content, which is preferred as a buffer material due to its high swelling capacity, low hydraulic conductivity and chemical resistance.

In the present study, a series of laboratory experiments were conducted to investigate the volumetric deformation behavior of bentonite at 80 °C. Tests were performed on the samples kept at 80 °C to observe the effect of high temperature on the volumetric deformation of bentonite in short and long (6 months and 1 year) terms. Glass fiber (GF) was added to bentonite due to its favorable engineering properties at high temperatures. The results have shown that high temperature increased the compressibility of bentonite mixtures while decreasing swelling deformation. The compressibility of the mixtures after curing decreased. Compared to room temperature (RT), the compression strain increased by 22.8% at 80 °C. With 6-months curing at 80 °C, it further increased by up to 33.2%. However, after 1-year curing, a slight decrease of 4.9% was observed. GF significantly increased the swelling behavior of bentonite at RT. However, this effect decreased at high temperature.