Physiomechanical of Residual Soil Contaminated with Zinc Heavy Metals

Abstract

The rapid industrialization and radical development that has taken place in today's modern society, be it agriculture, construction, industry, soil degradation or heavy metal contamination of soil, is one of the most serious ecological and environmental problems, which continuously poses a serious threat to sustainable development. Heavy metals may change the geotechnical properties of soils, making it difficult to reconstruct buildings on those sites because the parameters of the contaminated soil are unknown. Contamination by heavy metals will lead change soil’s structure, pore characteristics and behaviour, resulting in changes in soil permeability, plasticity, compressibility, in terms of strength and eventually affecting the structural integrity. The main objective of the present investigation is to enhance the understanding of the impact of the significant and hazardous heavy metal, zinc (Zn), on the geotechnical properties. The residual soil was subjected to Compaction Test and Atterberg Limit Test for each analysis, which was assigned a number up to six samples, one of which was left uncontaminated. The remaining samples were combined with a ZnSO4 solution, with values ranging from 0 mg/L to 4000 mg/L and increased by 500 mg/L intervals. The findings reveal that as the penetration increases in liquid limit test, moisture content also increases where at the same time, plasticity index increases proportional to concentration of zinc contaminant producing soil with high plasticity. This outcome is in contrast with the increasing of concentrations where the pattern is more likely to shift to a lower value of moisture content. Based on the findings, the presence of heavy metal contaminants in soils leads to degradation of geological properties, including changes in mechanical behaviour and geotechnical properties based on the double diffuse layer theory. Increased zinc heavy metal concentrations lead to reduced water adsorption capacity of soil particles.