Physical–Mineralogical–Chemical Characterization of Carbide Lime: An Environment-Friendly Chemical Additive for Soil Stabilization

Abstract

Increased use of industrial residues for soil stabilization is a necessary practice for sustainable geotechnics. The present study investigates carbide lime, the residue resulting from the production of acetylene gas, for its potential use as a substitute for commercial lime in soil stabilization. Carbide lime obtained from a plant in southern Brazil was characterized for its physical properties and morphology based on grain size distribution, specific surface area, scanning electron microscopy and energy dispersive X-ray spectroscopy, mineralogy based on X-ray diffraction analysis and thermogravimetric analysis, and chemical composition by X-ray fluorescence spectrometry and wet chemical analysis. The total and leachable toxic heavy metals concentrations were also determined by the U.S. EPA acid digestion and ASTM water shaking standard procedures. The improvement in mechanical behavior with an increase in the carbide content and curing period was demonstrated by increased unconfined compressive strength. Carbide lime consists predominantly of portlandite [Ca(OH)2] mineral and possesses characteristics similar to commercial lime, and is also nonhazardous. Overall, results from this study show that carbide lime possesses excellent physical, mineralogical, and chemical characteristics and is environmentally benign for use as an alternate low-cost, effective amendment for soil stabilization.