Tensile strength and crack pattern during desiccation of compacted clayey soils

This study presents desiccation tests performed on a constrained desiccation box, designed to measure
tensile strength and investigate crack formation during desiccation in compacted clayey soils. Tests were
conducted on three clayey soils of varying plasticity, under two sets of boundary conditions: one rigid
condition and one unrestrained condition. On the other hand, hydro-mechanical properties of the soils are
characterized in terms of compression and tensile strengths at various suctions, water retention properties
and free shrinkage curves. The soil behavior in the desiccation box is analyzed in the light of unsaturated
soil mechanics concepts. Results demonstrate that the development of crack pattern depends on the kinetics
of drying, and the shrinkage potential of the soil. The high plasticity soil exhibits a distributed crack pattern
due to the internal constrained induced by the suction gradient along the 3 cm thickness of the soil,
independently of the constrained conditions at both ends of the box. On the contrary, for lower plasticity
soils, a single crack occurs approximately in the middle of the specimen when the conditions are
constrained, while no crack occurs upon free shrinkage conditions.