Effect of specimen preparation on water retention and deformation behaviour of unsaturated soils

A series of water retention and mechanical tests and Mercury Intrusion Porosimetry (MIP) on unsaturated compacted and reconstituted specimens of a non-expansive clay, were performed to investigate effect of the specimen preparation on the water retention behaviour and its pore-size distribution, as well as investigate effect of suction on mechanical behaviour. The experimental results indicate that the air-entry value of the reconstituted specimen is higher than that of compacted specimen with the same void ratio. This is because the reconstituted specimen exhibits a unimodal pore-size distribution and its pore-size has a uniform distribution from the results of MIP tests. The soil-water characteristic curves and residual water content of two differently prepared specimens are almost the same in the high suction region. Secondly, the void ratio of reconstituted specimen decreased with increasing the suction under the isotropic net stress of 20 kPa, while the void ratio of compacted specimen shows a little change during the same suction equilibrium process.