Effect of Alkali-Activated Rice Husk Ash on The Strength Improvement of Compacted Koronadal Fine Sandy Loam Using Direct Shear Loading

The establishment of more construction sites in areas with poor ground quality, such as Koronadal City, is therefore unsuitable for large-scale construction. The main idea of this study was to assess the feasibility of using alkali-activated rice husk ash (AA-RHA) to improve the strength and binding properties of the Koronadal fine sandy loam (KFSL). The effects of AA-RHA on the characteristics of KFSL and strength parameters were measured using tests like sieve analysis, specific gravity test, liquid limit test, plastic limit test, soil compaction test, and direct shear test. The sieve analysis suggested that KFSL did categorize as a "poorly-graded" material. The soil indices indicated that KFSL possesses brittleness. The specific gravity reduction of up to 6.6 percent and the decrease in the maximum dry unit weight up to 10.45 percent were attributable to the presence of RHA in the soil mix. The increase in the OMC up to 32.38 percent was related to the higher porosity of soil mixtures with RHA. The abrupt decrease in cohesion was attributable to the inclusion of 5 percent AA-RHA in the soil. However, adding 10-20 percent of AA-RHA showed a gradual increase in cohesion compared to the soil with 5 percent AA-RHA content and higher than the natural KFSL up to 26.73 percent. Although the confined KFSL with 20 percent AA-RHA content recorded the most increased friction angle of 38.957° among the confined specimens after seven days of curing, it was still lesser than the naturally compacted KFSL. There was a gradual increase in the value of cohesion of the natural and confined KFSL with AA-RHA content concerning the curing time. The study also concluded that the value of the friction angle of the natural and confined KFSL with AA-RHA content fluctuated during the curing period. Lastly, the mode of failure of KFSL improved from brittle to ductile with the addition of AA-RHA content. Hence, this study has proven that the addition of AA-RHA was influential in the strength improvement of KFSL.