Fundamental Study on Consistency, Compaction, and Strength Properties of Soils Treated with Rice Husk Ash

Highway, road, and airfield construction on weak soils is costly endeavor. Re-use of agricultural waste is widely employed as a stabilizing agent to improve engineering properties of these soils. In this study, rice husk ash (RHA), a by-product of incineration of husk from rice production, was used as a potential stabilizer. The water absorption and retention rate of the stabilizer, denoted as W_ab, is determined by measuring the amount of water that is absorbed and retained by the stabilizer in relation to its initial dry mass. The study involved treating Ao clay, imitating a dredged soil with high water content, at various addition ratios (A_RHA). Diverse curing periods were applied to assess the liquid limits (w_L), plastic limits (w_P), and cone index (q_c) of the treated clays. Compaction characteristics were also determined for several A_RHA and different curing periods. The test results show an increase in both w_L and w_P with decrease in plastic index (I_p) with increase in A_RHA, but no remarkable change in w_L and w_P associated with curing. Compaction characteristics show a decline in ρ_dmax and increase in w_opt with increase in A_RHA, but no notable changes in ρ_dmax and w_opt with cured samples. Increase in q_c with A_RHA, but no noteworthy change in q_c with curing was discerned through cone index test. The trends for curing observed in the above test results were consistent with that observed for W_ab. The results were then modified based on the W_ab of stabilizer. The measured water content (w) and liquidity index (I_L) were modified to account for absorbed water (w*), which gave a better correlation with q_c than w. The compaction characteristics were also modified based on W_ab, A_RHA and the results suggest that treated clays were able to achieve modified dry density (\(\rho_{{{\text{d}}\max }}^{*}\)) at the same values of modified water content (\(w_{{{\text{opt}}}}^{*}\)).