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

Pozzolanic reactions of rice husk ash (RHA) entirely depend on controlled burning condition. The current study illustrates the effects of controlled burn RHA on the geotechnical properties of A-2-4 soil as per the American Association of State Highway and Transportations Officials (AASHTO) classification. The compactibility, bearing capacity, compressive strength, shear strength, and scanning electron micrographs were investigated as the important geotechnical properties of soil with 0%, 5%, 10%, and 15% of RHA admixtures considering the 7-day moist curing. The test results showed that the optimum moisture content increased, but maximum dry density reduced with the increment of RHA content. Soil with 5% RHA showed the increased percentage of California bearing ratio (39.5%), unconfined compressive strength (6.0%), modulus of deformation (56.3%), cohesion (11.8%), and angle of internal friction (6.3%) compared to untreated soil specimen which indicated that the application of burnt RHA at a controlled temperature enhanced the geotechnical properties of soil. Scanning electron microscopy image on soil with 5% RHA also observed the best microstructural development, which recom- mends that soil with 5% RHA can be used as a construction material for rural roads and pedestrian roads.