Resilient Characteristics of Asphalt Stabilized Soil

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The resilient behavior of asphalt stabilized subgrade soil in terms of changes in the deformation and shear failure under repeated loading was investigated in this work. Asphalt stabilized soil specimens of two sizes (100 mm diameter and 70 mm height) and (152 mm diameter with 127 mm height) have been prepared in the laboratory and compacted to its maximum dry density at optimum fluid requirement (water + liquid asphalt) and at 0.5% of fluid above and below the optimum. Specimens have been subjected to curing, then tested for deformation and resilient modulus under repeated shear stresses. The deformation was captured along the load repetition process with the aid of linear variable differential transformer (LVDT) under controlled stress and environmental conditions in the pneumatic repeated load system (PRLS) until failure. The large size specimens were tested under single punching shear stress, while small size specimens were tested under double punching shear stress after eight days of curing. The resilient deformation data of the two testing techniques under single and double punching shear stress was analyzed and compared. It was observed that the Double punching shear exhibit higher resilient strain than that of single punch shear in a range of (22, 8, and 24)% for (16.5, 16, and 15.5)% of fluid content respectively. The resilient modulus decreases after 1200 and 1800 load repetitions by (48, 47, 61, and 32)% and (50, 48, 63, and 34)% for (untreated soil, 15.5, 16, and 16.5)% fluid content respectively as compared to that after one load repetition under single punch shear stress. It was concluded that asphalt stabilization exhibit positive impact on resilient modulus. It increases by a range of three and seven folds under single and double punch shear stress after one load repetition by the addition of asphalt. Higher asphalt content exhibit reduction of Mr. Significant reduction in total and resilient strain could be detected after liquid asphalt was implemented in the subgrade soil.