Experimental Study for the Effect of Additives Silica Fume on the Properties of the Synthetically Contaminated Soil

Abstract

This paper aims at studying the impact of the reaction that occurs between contaminants present in the soil and silica fume added on the chemical, physical and mechanical properties of the soil. The soil samples were contaminated in the laboratory with nickel nitrate (Ni(NO3)2). Silica fume (SF) was added to three different ratios (3%, 5%, and 10%). Several laboratory experiments were conducted to study soil characteristics before and after adding silica fume to the contaminated soil. The results revealed that the increment percentage of liquid and plastic limits was obtained with an increase in the percentage of silica fume additive to the nickel-contaminated soil. Notably, the maximum dried densities were decreased by increasing silica fume ratios to the nickel-contaminated soil, while the optimum water content increased with increasing silica fume ratios to the nickel-contaminated soil. The value of organic matter for soil samples was roughly equal numbers ranging from 3.33% to 4.07% (i.e., no change in the organic matter for soil samples mixed with different ratios of silica fume). The coefficient of consolidation (Cv) increased from 0.0026 in a soil sample that was contaminated with nickel ions at a concentration equal to 750 mg/kg without adding silica fume to 0.0755 in a soil sample contaminated with nickel ions at a concentration of 750 mg/kg mixed with silica fume at a ratio of 5% and then decreased to 0.00531 in a soil sample contaminated with nickel ions at a concentration of 750 mg/kg mixed with silica fume at a ratio of 10%.