Tensile Strength of Compacted Clays during Desiccation under Elevated Temperatures

Abstract

Abstract The tensile strength of unsaturated soils is a critical factor controlling the initiation and propagation of desiccation cracks, which can threaten the structural integrity of natural and man-made earthen structures and slopes. Several engineering applications involve unsaturated soils subjected to elevated temperatures (e.g., earthen structure-atmospheric interaction under prolonged droughts, nuclear water disposal, energy piles, ground source heat pumps). Although the temperature dependency of desiccation cracking is demonstrated in the literature, critical gaps remain regarding the characterization of the tensile strength under elevated temperatures. The main objective of this study is to investigate the effect of elevated temperature on the tensile strength of unsaturated clays during desiccation. To accomplish this objective, a novel testing setup that can be used to directly determine soil tensile strength during desiccation was placed in an oven to measure the tensile strength of two compacted clayey soils of medium to high plasticity under different temperatures ranging from 20°C to 60°C. The clays are compacted at 95 % of their respective maximum dry unit weights over a range of water contents from dry to wet of optimum to investigate the influence of initial water content on tensile strength. The results demonstrated that the tensile strength decreased with increasing temperature. At the optimum water content, a tensile strength reduction of 36 % and 27 % in the highly plastic clay and the medium plastic clay, respectively, was observed when the temperature increased from 20°C to 60°C. Additionally, for the partially saturated condition, the initial water content affected the tensile strength significantly. Temperature-induced changes in key factors contributing to the tensile strength of unsaturated clays are discussed to provide further insight into tensile strength of clays at elevated temperatures. The findings of this study can contribute toward a more realistic analysis and design of earthen structures subjected to elevated temperatures.