Influence of freeze–thaw cycles on strength and small strain shear modulus of fine-grained soils stabilized with nano-SiO₂ and lime using bender element tests

Improving the properties of fine-grained soils with nanotechnology has recently been widely considered in geotechnical engineering practice. In this paper, the effect of freeze–thaw cycles on the strength and stiffness properties of clay soil stabilized with nanosilica and lime has been examined at various curing periods. To this end, several unconfined compressive strength and bender element tests have been performed on stabilized samples experiencing consecutive freeze–thaw cycles. The results show that, for the samples stabilized with nanosilica and lime, the uniaxial strength and small strain shear modulus increase by increasing nanosilica up to 1.5% and lime up to 7%, and decrease thereafter. In addition, freezing and thawing cycles were observed to have a significant impact on the reduction of the strength and stiffness properties of both untreated and treated specimens. Accordingly, the maximum shear modulus and compressive strength of the clay sample stabilized with 1.5% nanosilica and 7% lime reduced by 50% and 57%, respectively, after exposing to 9 freeze–thaw cycles. For the untreated samples, the reductions in strength and stiffness due to freezing and thawing were more severe, i.e., approximately 100% and 68%, respectively. The shear modulus values were almost constant in the range of the first to the third freeze–thaw cycle and decrease thereafter.