Use of Phosphoric Acid and Rice Hulk Ash as Lateritic Soil Stabilizers for Paving Applications

Phosphoric acid (H 3 PO 4 ) is a product that can be used as a stabilizing additive for tropical soils in an exploratory manner by the construction industry. For the drying process of this grain, its husks are used as fuel for ovens, generating rice husk ash (RHA), which is considered an environmental liability if not reused. In this sense, this paper aimed to evaluate the resilient behavior and the simple compressive strength, at different curing ages, of the use of rice husk ash and phosphoric acid in a simple and combined mixture for the stabilization of lateritic soil. The lateritic soil was mixed with different contents of RHA, H 3 PO 4 , and water and compacted in intermediate and modified Proctor energies. Fractured soil samples in the mechanical compressive strength tests were analysed by scanning electron microscopy and X-ray diffraction. The results show the potential for stabilization of the lateritic soil in question in terms of resilience and simple compressive strength through the addition of RHA and H 3 PO 4 at different curing ages. The insertion of only H 3 PO 4 produced the most satisfying resilient behavior. By adding RHA, the strength properties were improved, and good mixtures were obtained for use in paving.