The void ratio dependency of the retention behaviour for a compacted clay

The paper presents the results of a comprehensive experimental programme aimed to characterize the retention properties of a compacted scaly clay by determining the retention curves in terms of main wetting and main drying branches at different values of void ratio, ranging between 0.45 and 0.80. Different experimental techniques were combined in order to explore the retention properties in a wide range of suction. Vapour equilibrium technique was used to impose total suction in the range 2 110 MPa, while the air overpressure technique was applied to control matric suction in the range 0.01 0.80 MPa. Collected results clearly pointed out a strong dependence of the retention curves on the void ratio. The dependences of the air entry value and of the hysteresis on the compaction state of the material are analysed. These aspects are discussed in the light of the microstructural arrangement resulting from the compaction process.