Effect of Recycled Gypsum on Geo-Environmental behavior of Laterite Soil

Abstract

Approximately 1.6 million tons of gypsum waste plasterboard are produced annually in India. As such, it is essential to find an alternative way to reduce the quantities of this waste material to avoid environmental problems and the high cost of disposal in landfill. This report describes the use of recycled gypsum, which is derived from gypsum waste plasterboard, to improve the strength of laterite soil with taken in consideration environmental impacts. Four different recycled gypsum contents ranging from 0 to 10% was investigated. For this purpose, a series of unconfined compression tests were conducted to evaluate strength performance of treated soil. While a series of environmental tests were conducted to explore pH, solubility concentration of fluorine, boron, and hexavalent chromium in the untreated and treated soil specimens. The early curing days for soil-gypsum mixture had a significant effect on strength performance compared to the later days. The use of recycled gypsum within the investigated limits had no adverse effect on pH value. As well, the solubility concentrations for fluorine, boron, and hexavalent chromium were found within the permitted standard limits up to adding 10% of gypsum content.