Influence of Curing Time on the Resilient Modulus of Chemically Stabilized Soils

Research was conducted to investigate the influence of soil properties, additive type and curing time on the resilient modulus (MR) of chemically stabilized soils. Interest in characterizing the rate of MR improvement through curing time was the primary motivation for this study. Soils stabilized with cement kiln dust and Class C fly ash were collected at five construction sites in Oklahoma. Specimens were prepared at optimum compaction parameters and tested after various curing periods; a total of 58 MR tests were performed. Properties of both soils and admixtures were evaluated in order to correlate those with the enhanced behavior of the mixed soils measured as improved MR values. Regression equations were developed so that MR evolution with time could be quantitatively described. After 28 days of curing, tested soils showed improved MR values ranging from 7 to 46 times larger than those of untreated soil. Rates of improvement were characterized using a power type regression analysis. Although data are limited, correlations between improvement rate (Rt) and raw soil properties including fines fraction, pH, and to a lesser extent, specific surface area and cation exchange capacity, indicate these factors show promise as predictors of MR improvement with time.