Characterization of stress-strain response of thermally cured lime stabilized expansive clay

a high plastic clay (CH) soil was treated with lime contents of 3%, 5% and 7%. The soil-lime mix was compacted to required unit weight at room temperature and cured at temperatures of 5 degrees C, 30 degrees C and 50 degrees C for 7, 14 and 28 days. Unconfined compression tests were performed on the cured samples. The purpose of the test was to obtain stress-strain response of the stabilized specimens and also to examine the nature of failure of specimen. The sample cured for longer period showed higher strength and stiffness irrespective of the lime contents. The stressstrain response of sample cured for 7 days curing showed clear peak followed by strain softening response whereas the 28 days cured sample showed distinctly different response and it has exhibited sudden failure after reaching the peak strength, indicating brittle failure. The stress-strain response is more linear upto yield point afterwards simply breaks or collapses. The uniaxial compression failure of 28 days cured sample seems to take place in two stages. In the first stage, the cracks develop in the direction of loading (tensile cracks). Thereafter the cracks grow with increasing load until specimen splits into vertical columns which ultimately failed by buckling or shear. In the case of sample cured at lower temperature the mode of failure is general shear. Overall there is an increase in strength and stiffness with curing temperature and curing period and the samples cured for longer period at elevated temperature shows liner response even at strain level higher than the strain corresponds to yield stress of stabilized soil cured at lower temperature.