The effect of curing time and freeze-thaw cycles on the un-drained shear strength of lime-stabilized alluvial soils

Abstract

This paper presents an experimental effort to elucidate the stabilization mechanism of alluvial soils with lime and check their durability against freeze and thaw (FT) cycles. The effect of stabilization-related parameters such as lime content and curing period were investigated. The lime content was changed as 0, 3, 6, 12 %, while curing periods were 7, 28, and 56 days. The mixtures were kept in a closed system cabinet at -24 and +24 Celsius degrees for 24 hours to expose the samples 0,1 and 2 FT cycles. To analyze and compare the effect of FT cycles, Unconsolidated-Undrained (UU) triaxial tests were performed under different cell pressures. In addition, SEM and EDAX analyses were conducted to evaluate the mechanism at the microstructural and compositional levels. It was determined that the highest strength could be obtained in the samples in which 6% lime content was kept in 28 days of cure. After this curing period, it has been determined that minerals that affect the mechanism between lime and soil adversely were formed. The fact that the development of chemical reactions stopped or did not progress in the 56-day curing period has confirmed the production of such minerals. However, these samples, whose strength did not increase as expected, were not affected much by FT cycles. It means, no significant difference was obtained from cycles 1 to 2, since a major part of the sample’s integrity was affected from the first cycle. The deterioration of the soil integration and growth of needle-like harmful minerals in the long term were also verified with the SEM images and EDAX analyses.