SWOLLEN DENSITIES OF SUBGRADES IN BLACK COTTON SOIL AREAS

The present study purports to evaluate the factors such as initial moulding moisture content and compacted density, which influence the loss in swollen of black cotton soils. Swollen density is defined as the lowest value of to which a compacted soil swells upon free absorption of moisture. A large number of laboratory tests were performed on two black cottom soils, to determine the variation in their swollen densities when compacted initially to different densities, at varying moisture contents. The initially compacted densities varied from 1.3 gm/cc to 1.60 gm/cc while the moulding moisture contents ranged from values below the OMC, at OMC and to values about the OMC. Laboratory test results show that the loss in swollen can be minimised appreciably by using moisture contents on the higher side of OMC. Besides, it is shown that compaction of black cotton soils to higher densities, in order to achieve higher strength of the subgrade, is advantageous only if done at water contents well above the OMC. /Author/