SHEAR STRENGTH BEHAVIOUR OF REMOULDED FINE-GRAINED SOILS TREATED WITH HYDRATED LIME

Abstract

This paper presents an experimental study to assess the effect of lime treatment on the shear strength of low plastic clay and silt soils. The triaxial and direct shear tests determined the total and effective shear strengths for soil samples of the CL and ML soil groups prepared in their natural state and after treatment with 2% and 4% hydrated lime. The test specimens were initially compacted at their standard Proctor OMC and MDD conditions and allowed to cure before being tested. The study showed that the addition of lime significantly affected the basic properties of the soil types by modifying their gradation, rendering them non-plastic, and changing their OMC and MDD values. The lime treatment produced positive results by improving the total and effective soil strengths; however, the two study soils responded differently. Significant shear strength improvements were achieved in the lime-treated CL soil, but generally, the effect was relatively small for the ML soil. The gain in soil strength due to lime addition may be attributed to the clay particles flocculation and aggregation, increasing the adequate grain size, thus improving the soil matrix strength. In general, the addition of hydrated lime produced increases in the soil cohesion and reductions in the angle of internal friction; however, the effects are more pronounced in the CL than in the ML soil. Different effective strength parameters were revealed from the CU and DS test methods. The former tended to give higher cohesion and lower friction angles compared to the latter.