In Situ Alteration of the Hydro-Mechanical Behaviour of a Compacted Stabilised Expansive Soil

This paper assesses the performance of an embankment constructed in 2010 with a stabilised expansive soil. Two types of treatment were employed at construction time: 4% lime and a mix of 2% lime and 3% cement. A sampling campaign was carried out in 2021 to evaluate the long-term performance of the stabilised soil properties. To assess the compressibility of the soil, oedometer tests were carried out on samples from different parts of the embankment. The results were compared to the compression curve of the untreated soil, also sampled in the same embankment. Complementary shrinkage tests were performed to investigate the effect of the treatment on swelling and shrinkage. The obtained results show that the yield stress of the material from the outer part was inferior to 100 kPa, similarly to the yield stress of the untreated soil, demonstrating a strong alteration in the effect of both treatments over time. This alteration was noticeable to a distance of approximately 2 m from the external surface. Beyond this distance, the performance of the soil was comparable to the behaviour of recently treated soil, with yield stresses close to 1000 kPa. These observations, similar for each treatment dosage, raise questions as to the durability of the treatment on the outer part of the backfill.