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An experimental investigation was carried out to evaluate the influence of fines content on the hysteretic behavior of water-retention characteristic curves (WRCCs) of reconstituted soil subjected to wetting and drying cycles. The red soil fines were collected from the Indian Institute of Technology Hyderabad, Kandi, Sangareddy. An Indian Standard Grade-II sand (i.e., Ennore sand) was reconstituted including red soil fines content of varying percentages (30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%) by dry weight of sand to produce different soil mixes. The filter paper method was adopted to measure the effect of the fines content on the WRCCs for both drying and wetting cycles. Experimental results revealed that the presence of fines influences the shape of the WRCC. The results further revealed that the WRCC of soil is hysteretic in nature as the water content is less in the wetting path compared to that in the drying path at a constant suction value. Nonlinear regression equations are proposed for the fitting parameters of the WRCC in terms of the liquid and plastic limits for the drying WRCC based on the experimental results. The present study also proposes nonlinear regression equations to predict fitting parameters of the wetting WRCC in terms of the fitting parameters of the drying WRCC. The proposed nonlinear equations are validated for soil collected from Padakal village, Mahbubnagar district, Telangana state, India. A formulation is presented to predict the degree of hysteresis based on the uniform slice method to evaluate the effect of fines content on the hysteretic behavior of WRCCs. The proposed regression fits were compared to existing fits in the literature to validate their authenticity.
Raghuram et al. (Fri,) studied this question.