Performance Evaluation of Rice Husk Ash and Phosphogypsum in Stabilizing the Problematic Expansive Soil

Abstract

Various remedial measures adopted to overcome the problems posed by expansive soils like soil replacement, moisture control, prewetting, and lime stabilization have been practiced with varying degrees of success. However, these techniques suffer from certain limitations with respect to their adaptability. Stabilization using solid wastes is one of the emerging techniques to improve the engineering properties of expansive soils to make them suitable for use in construction. This paper presents an attempt made to study the influence of two wastes, rice husk ash (RHA), an agro-waste, and phosphogypsum (PG), an industrial waste from fertilizer industry, in different percentages, as stabilizing materials to improve the properties of problematic expansive soil. The percentage of phosphogypsum (PG) was varied from 0 to 8% with an increment of 2% in combination with 0, 5, and 10% percentages of rice husk ash (RHA). Different tests in the laboratory were conducted to evaluate the characteristics of treated expansive soil. The analyzed results clearly depict that the combination of 10% RHA + 6% PG had significantly improved the soaked CBR value and unconfined compressive strength (UCS) by about 3 times and 96%, respectively, when compared to that of virgin expansive soil. The parametric evaluation summarizes that the combined effect of waste materials phosphogypsum (PG) and rice husk ash (RHA) had shown promising influence on the strength characteristics of expansive soil, thereby giving a twofold advantage in improving problematic expansive soil and also solving a problem of waste disposal.