Compressibility of Residual Soil with Different Zinc Concentrations

The presence of heavy metal in soil poses major threats to the environment and integrity of structures. Rapid industrialization further increases the rate of contamination of heavy metal in soil. The presence of heavy metal contaminants in soil changes the geotechnical properties of soil, which will affect the structure atop the contaminated sites. Changes in mechanical properties of soil could alter the compressibility behaviour of soil. The purpose of this research is to determine the compressibility behaviour of zinc contaminated residual soil with different concentration levels of zinc. A total of thirty samples including a control sample were prepared with ZnSO4.7H20 concentrations of 0 mg/L, 500 mg/L, 1000 mg/L, and 2000 mg/L with curing period of 0 days, 7days, and 28 days. The samples were tested for One- Dimensional Consolidation Oedometer test, pH test, and Electric Conductivity test. The results show a decrease in compression index value, void ratio, and coefficient of consolidation as the concentration of zinc increases. Compression index value decrease to the lowest value of 0.143 under 2000mg/L concentration at 28 days curing period. Void ratio achieves the highest value with 500 mg/L concentration at 7 days curing period while the control sample shows the lowest void ratio value. As for coefficient of consolidation, the highest value is achieved for sample with 500 mg/L at 7 days curing period where the control sample shows the lowest value. The pH value of soil declines to acidic value from 5.82 to 3.84 under concentration of 2000 mg/L at 28 days curing period while electric conductivity increases from 156 μs/cm to 2990 μs/cm at 0 days curing period.