Effects of Na2SO4 on the geotechnical properties of clayey soils stabilised with mineral additives

Abstract

An experimental investigation was undertaken to study the effects of sodium sulphate (Na2SO4) on the behaviour of two clayey soils stabilised with lime (L), natural pozzolana (NP) and their combination (L–NP). The geotechnical properties investigated are the Atterberg limits and unconfined compressive strength (UCS) on samples cured for 1–120 days curing period. The results show that the L and L–NP reduce the plasticity index (PI) and increase the UCS of two clayey soils. However, the PI of these soils increases when the Na2SO4 is present. In addition, higher UCS values are recorded with 2% Na2SO4. But at later stage, the samples containing 4 and 6% Na2SO4 were completely deteriorated due to the formation of ettringite mineral. In general, the effect of Na2SO4 on the soil stabilisation process depends on the type of additive and its content, the soil nature, the Na2SO4 content and the curing period.