Effect of palm shell ash and phosphoric acid chemical solution on subgrade material towards CBR value

Abstract

Soil stabilization is a process of mixing soil with particular materials to restore engineering properties of soil which is an attempt to change or fix the engineering properties of soil in fulfilling particular technical requirement. The examination result of soil as a subgrade coating conducted in this study is classified as expansive soil. Unfixed subgrade condition may cause various damages on road pavement. Thus, in this study, subgrade repairment was administered by utilizing stabilization method of a mixture palm shell ash (PSA) and phosphoric acid chemical solution. The experiment aims to decrease dependency of cement as stabilization material in regular usage, in order to save cost in economic aspect of infrastructure. This study intends to analyze the effect of palm shell ash and phosphoric acid addition towards CBR value as subgrade construction layer of road pavement. The study outcomes shows several conclusions: (1) the decreasing value of optimal water content, plastic index, and swelling; (2) the increasing value of unsoaked CBR, soaked CBR, and isolated CBR. (3) the stabilization material mixture has been achieved, therefore it can be used as subgrade repairmen on expansive soils for minimum standard of subgrade coating for road pavement.