Effect of Calcium Sulphate on the Geotechnical Properties of Stabilized Clayey Soils

Abstract

An experimental investigation was undertaken to study the effect of calcium sulphate (CaSO₄.2H₂O) on the behaviour of the grey clay (GS) and red clay (RS) soils stabilized with lime (L), natural pozzolana (NP) and their combination (L-NP). In this study, the geotechnical properties investigated are respectively, the Atterberg limits on samples cured for 1 to 30 days to assess the diffusion time effect of CaSO₄.2H₂O (DTC) in the soil paste and the unconfined compressive strength (UCS) on samples cured for 7 to 120 days. The results show that both GS and RS samples can be successfully stabilized with L alone or with L-NP which substantially reduce their plasticity index (PI) and increase their UCS. On the other hand, a negligible effect was reported when the NP is used alone. However, when combining a fraction of CaSO₄.2H₂O to samples containing L or L-NP, a further decrease in the PI is observed. In addition, higher UCS values are recorded.