Prediction of the resilient modulus of stabilized weak subgrade for pavement design structure

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This study was performed to propose an effective method for evaluating the resilient modulus for stabilized weak subgrade soil. The data used in this study was conducted in two phases. Three different subgrade soils having low, medium, and high plasticity were selected and considered for Phase I, and four different subgrade soils of low, medium, high, and heavy clay were selected and considered for Phase II. For Phase I, three various Moisture Content (MC) was chosen at the Optimum Moisture Content (OMC) ± 2 %. For Phase II, three different MCs were chosen on a higher than optimum moisture content wet side. The subgrade soils were treated with cement, a combination of cement and lime, and a combination of fly ash and lime. The laboratory-molded specimens were subjected to repeated load triaxial testing to determine their resilient modulus (Mr) under cyclic loading and the physical properties of the compacted specimen. Regression analysis was performed to develop a new equation that can estimate the resilient modulus parameters of stabilized weak subgrade soils. The estimated and measured resilient modulus (Mr) coefficient values were found to be in good agreement. The Monte Carlo simulation method was used to predict the probability of failure to predict the resilient modulus of stabilized weak subgrade soils using the developed models. It was observed that the highest probability of failure associated with using the resilient modulus coefficient values developed in models is 7.2 % which corresponds to a Reliability Index, β = 1.46.