Amelioration of fat clay treated with cohesive and cohesion less soils

Abstract

The present study is aimed to evaluate the amelioration of fat clay by blending it with cohesive non-swelling soil (CNS) and cohesionless silty sandy soil (termed as Kassu). Fat clay sample with liquid limit (LL) 50, plasticity index (PI) 26 was collected from a site located near Narowal city while CNS and Kassu samples were procured from sites located at outskirts of Lahore (Pakistan). Geotechnical parameters evaluated after conducting tests on virgin soil indicated it as unsuitable soil for construction purposes. A series of laboratory tests were performed after blending fat clay with CNS and Kassu in different proportions ranging between 0 ~ 35% with 5%intervals. The laboratory tests including modified Proctor compaction, unconfined compression, California bearing ratio (CBR)and one-dimensional consolidation tests in addition to classification tests were performed on virgin and blended samples. The LL decreased from 50–32% and PI reduced from 24 to 13 with 35% addition of CNS while for Kassu LL and PI reduced to 29% and 12, respectively. CBR value of blended samples increased from 4–7% making the blended soil an acceptable subgrade for roads and foundation construction. Also, swell potential reduced from 4–1.2% ~ 0.26% for blended samples. Regression models have been proposed to predict swell pressure and ultimate swell potential of CNS and Kassu-treated swelling clays. Based on the study, it was concluded that significant improvement in mitigating expansive characteristics of fat clay can be achieved by blending it with CNS and Kassu. Meanwhile, CNS is observed to be more effective as compared to Kassu in controlling the swell properties of the fat clay.