Assessing effectiveness of thermal treatment and mixing with coarse-grained particles in stabilization of marly soils

Abstract

Marly soils can show problematic behaviors such as swelling and dispersion when subjected to water. It can cause problems for various civil constructions, including building foundations, water conveyance canals, highways, and airport runways; so appropriate measurements should be taken to stabilize these soils. In this study, two stabilization methods, including thermal treatment and mixing with coarse-grained particles, were utilized to limit swelling of marly soil samples collected from around the Sonqor city and also to improve their strength properties. The results of experimental tests showed that thermal treatment in high temperatures (after 100 °C) led to a decrease and an increase in liquid and plastic limits, respectively, and subsequently plasticity index decreased. However, after 475 °C, the Atterberg limits were almost unchanged. Also, it was found that with increasing heating levels, the swelling potential of the soil samples decreases as free swelling index values of the samples changed from 13.9% (high swelling potential) at 100 °C to 0.89% (low swelling potential) at 500 °C. Based on the experiments, it was observed that by adding 30% of coarse particles to the marly soil samples, engineering properties such as maximum dry density (γdmax), California bearing ratio, and unconfined compressive strength have been improved up to 10%, 59%, and 30%, respectively. Therefore, the stabilized marly soils could be considered as appropriate construction materials.