Investigation of volume change behavior on a clay with high plasticity for different initial conditions

Abstract

When high plasticity clays are used in high fill construction, they can be subjected to high stresses. In this study, a high plasticity clay soil was used as fill material. When this soil is exposed to water under different stresses during its service life, volume changes are expected to occur. This volume change behaviour was investigated using a series of consolidation tests. The samples were prepared on the wet side of the optimum water content (wopt=%18.7, determined by the modified compaction method, (w(opt+5)= %23,7 and w(opt+7)=%25,7) at relative compaction (R.K.) of 90% and 95% (RK 90 and RK 95). In the first set of tests, one dimensional compression and swelling behaviour of the soil was investigated on the prepared samples were loaded under high stresses under conditions corresponding to the wetted state (S series tests) and the dry state (N series tests). The second set of tests investigated the swelling behavior when water is introduced to the samples under different vertical stresses. In the third series of consolidation tests (K), after the deformations were completed the long settlement (creep) behavior due to changes in the internal structure of the soil was investigated. In the 1st and 2nd set of compaction tests, it was observed that the tendency to swelling decreased with increasing water content and the volume change values increased up to 16 times especially in the samples in contact with water in case of high stress. According to the deformation rates obtained from the third set of tests, it was observed that no additional volume changes due to the internal structure of the soil were formed in the high plasticity clay.