Experimental investigation of binder based on rice husk ash and eggshell lime on soil stabilization under acidic attack.

This study evaluates the use of rice husk ash (RHA)-eggshell lime (ESL) and RHA-commercial lime (CL) as alternative binders for clayey soil stabilization, as well as the performance of soil-binder mixtures under acidic attack. A central composite design was carried out to analyze the reactivity by batch tests with a sulfuric acid solution. Physical and mechanical behavior was evaluated by compaction test and unconfined compressive strength (UCS). Reactivity tests demonstrated better neutralization of contaminant acidity for mixtures with ESL. The highest compressive strength, reactivity and partial encapsulation of toxic elements are associated with application of 30% RHA and 6% ESL in the soil. A C-S-H gel is observed in poorly crystalline phases through the XRD pattern. The application of RHA-ESL in soils exposed to acidic attack has environmental feasibility. Analysis of RHA grinding processes combined with the mixture strength over time, and its application tests in impermeable barriers, in landfills, are recommended.