Hydro-mechanical characterisation of a compacted expansive clay by suction controlled oedometer tests

The hydro-mechanical behaviour of compacted expansive Romainville clay was investigated. The soil was air-dried, crushed and passed through a 2 mm sieve before being statically compacted to a dry density of 1.35 Mg/m³. Various hydro-mechanical loading paths were followed in oedometer with controlled suction using the vapour equilibrium technique (suction s = 0, 9, 39, and 110 MPa). The vertical stress was applied in the range of 0-800 kPa. The experimental results show that: (i) wetting-induced swelling was higher at lower vertical stresses; (ii) the vertical stress under which no swelling occurred during flooding was estimated at 60 kPa; that can be considered as the swelling pressure of the soil tested; (iii) the soil compressibility (changes of volume upon stress increases) was strongly influenced by the soil suction: the lower the suction the higher the compressibility.