Effect of Silica Fume Addition on the Behavior of Silty-Clayey Soils

Abstract

The aim of this research is to investigate the effect of silica fume addition on the behavior of soil subgrades which has inadequate natural stability. Natural silty-clay soil and silty-clayey soil-silica fume mixtures were compacted at the optimum moisture content and subjected to various laboratory tests. The test results showed a significant improvement in swelling pressure and compressive strength of composite samples with silica fume. The swelling pressure decreased by 87% with increasing silica fume contents from 5% to 15% for all samples and the compressive strength of clay samples increased by 4% with increasing silica fume contents from 5% to 10% and after that, it decreased. It is observed that the permeability of soil increased with increasing silica fume content. The coefficient of permeability increased by 100% with increasing silica fume content to 15%. Also, the results show that the silica fume decreases the development of cracks on the surface of compacted clay samples by reducing crack width by 75%. The investigation showed that silica fume is a valuable material to modify the properties of soil subgrade to make them suitable for construction.