Effect of lime-stabilised copper slag cushion on swelling behaviour of highly plastic clay

Clay soil is prone to seasonal volume change due to variation in water content. The use of waste materials in civil engineering, especially in road construction, has been in vogue all over the world due to the development of road infrastructure. Copper slag is one such waste material available abundantly from the copper industry in India. This paper discusses the heave and swelling of copper slag-cushioned clayey subgrade prepared in a model test tank. The results revealed that the methodology adopted is effective in reducing the swelling of clay. The thickness ratios of the stabilised copper slag cushion and clayey subgrade bed adopted are 0.25, 0.5, 0.75 and 1.0. The copper slag cushion is stabilised with lime content varying from 2 to 10%. A reduction in heave of clayey soil subgrade bed is observed with an increase in the percentage of lime and the thickness of the copper slag cushion. For a cushion-clay soil subgrade thickness ratio h(c)/h(s) = 1, the reduction in the heave of a clayey subgrade bed is 84.4%. The swell potential observed from the present study follows well the trend obtained from the rectangular hyperbolic model.