Alkali-activated system of carbide lime and rice husk for granular soil stabilization

Abstract

This study investigated the utilization of an alkali-activated system to stabilize a granular soil. For the alkali-activated binder, rice husk ash was used as the precursor and carbide lime as the activator. An experimental program was carried out to analyze the strength and stiffness of sand-rice husk ash-carbide lime mixtures. Different binder contents (10 and 20%), dry densities (15.5, 16.5 and 17.5kN/m³), curing periods (7 and 28 days) and Ca/SiO2 ratios (1, 1.5 and 2) were evaluated. In addition, microstructural analyses were conducted on the mixed materials. The increase in binder content, dry density, and curing period led to the improvement of strength and stiffness, while the increase in Ca/SiO2 ratio hindered the mechanical behavior. The statistical analysis revealed that all studied factors influenced the mechanical behavior of soil-binder mixtures. In addition, the condition to obtain the highest strength and stiffness was evidenced in the combination of higher dry unit weight, binder content, curing period, and lower molar ratio. The alkali-activated system was shown to be a promising binder agent for soil stabilization for both strength and stiffness. Finally, two calcium aluminosilicate hydrate structures were identified in the soil-binder mixtures, soulunite and jaffeite, indicating ideal structures for the composition of cement hydrates.