Multi-scale analysis of the swelling and shrinkage of a lime-treated expansive clayey soil

The main purpose of this paper is to examine the impact of a wetting and drying path on the swelling/shrinkage of a compacted lime-treated expansive clayey soil both at the macro- and micro-scales. At the macro-scale, the soil water characteristic curves (SWRCs) of the compacted lime-treated materials (0%, 2% and 5% of lime content) were determined for three curing times (0, 28 and 180 days). The modifications at the micro-scale were assessed with mercury intrusion porosimetry (MIP) tests. The results showed that lime treatment was efficient to prevent the volumetric swelling from the initial state upon wetting. Even if no significant macroscopic volumetric variation was observed, a reorganisation of the microstructure was evidenced. Upon drying, the lime addition led to an alteration of the hydro-mechanical soil behaviour from the initial state by increasing the compacted shrinkage limit suction. However, the volumetric shrinkage of the compacted lime-treated samples remained on the same order of magnitude of the untreated compacted soil, regardless of lime content and curing time. At the micro-scale, the MIP tests showed that drying altered both the macro- and micro-porosity fabric of the lime-treated soils. This study showed that lime treatment had a limited effect on lime-treated compacted soil shrinkage whilst preventing swelling.