Justification of strength properties of microstructural changes in the black cotton soil stabilized with rice husk ash and carbide lime in the presence of sodium salts

Abstract

Black cotton soils exhibit high shrinkage and swelling characteristics due to the variation in moisture content. To overcome this problem, many techniques are adopted, among which is the soil stabilization technique. Rapid industrialization and urbanization lead to the generation of waste products; the major by-products are rice husk ash (RHA) and carbide lime (CL). These by-products show excellent pozzolanic property. In this paper, an attempt has been made to stabilize black cotton soil with rice husk ash (RHA) along with carbide lime (CL) and other additives. Based on strength test results, the optimum dosage of RHA and CL was found to be 20% and 8%, respectively. The effect of sodium salts on index properties and unconfined compression strength (UCC) test at different moulding water contents for immediate testing and at different days of curing are studied. Results show that plasticity index of the soil treated with additives was decreased both for immediate and for 7 days of curing period due to the decrease in diffuse double-layer thickness. Soil-RHA-CL composite treated with 1% sodium chloride and 1% sodium hydroxide improves the Unconfined compression strength and shows a better strength compared to carbide lime-treated soil due to the formation of alkali silicate and alkali aluminate hydrated gel along with other cementitious products. The microstructural changes in the stabilized composite can be observed with XRD and SEM analysis. The addition of carbide lime and salts binds the particle with hydrated gel and shows denser environment compared to unstabilized soil.

Shear strength of soil by using rice husk ash waste for sustainable ground improvement

“…Furthermore, adding modest amounts of cement and RHA (6RHA + 6C) enhanced the degree of cementation within the composite structure, decreasing the development of micro-pores and microcracks, as illustrated in Fig. 22 Other relevant studies have reported similar findings [51].…”

Experimental Study on the Mix Ratio of Restored Heritage Building Adobe

“…Figure 12 a–c are the SEM images of the lime mono-doped group 28 d. It is evident from Figure 12 a–c that the overall compactness of the single lime-doped group is relatively low, with obvious micro-cracks and large pores. With the increase of lime content, the Ca(OH) 2 generated by hydration increases gradually and is plate-shaped; when the lime content is 15%, the amount of calcium carbonate generated by carbonization is high, which can better fill the pores between soil particles, increase the soil density, and play the role of binding soil particles [ 30 ]. Secondly, the pores inside the sample decrease, which can effectively prevent the entry of water molecules and improve the water-resistance of the sample.…”

Effects of controlled burn rice husk ash on geotechnical properties of the soil

“…The SEM test results of soil with 0%, 5%, 10%, and 15% RHA are shown in Figures 6A-6D rough surface together with no spherical particles (Figure 6A). After adding RHA in the soil, the mechanical interconnection (Ramesh and Manjunatha, 2020) and pozzolanic reaction between the soil and RHA particles (Sarkar et al, 2012) altered the microstructure of the soil. The surface roughness of treated soil increased with the increment of RHA content due to increased pore spaces compared to the control specimen.…”