Effects of initial compaction condition and temperature on swelling characteristics of compacted bentonite

Abstract

Given that isolated high-level radioactive waste repository cannot be modified during operation, understanding the influence of the buffer's initial conditions is critical. This study investigates the influence of the initial dry density and water content on the swelling pressure and consolidation characteristics of Korean bentonite, which is a buffer candidate in the engineered barriers of the repository. In order to consider the high temperature repository condition, samples of various dry densities and water contents were tested at different temperature. Prediction models were developed using the test data and the models were used to analyze the effects of initial conditions. The research findings indicate that the influence of dry density, water content, and temperature on swelling pressure is not absolute and can show different tendencies depending on the case. In terms of consolidation behavior, the compression index and pre-consolidation pressure differ with dry density and temperature, while recompression is unaffected. The study's results align with prior research on compacted expansive clays, with the double structure of clay serving as a suitable explanation for the swelling phenomenon's dependence on the initial compaction condition.