The effectiveness of silica fume and calcite in improving the shear strength of clay soil

This study addresses the challenges associated with clay soils that have high plasticity and low shear strength in infrastructure development. It investigates an alternative soil stabilization method using a mixture of silica fume and calcite. The objective of the research is to evaluate the effectiveness of combining various concentrations of silica fume (6%, 8%, 10%, and 12%) with a fixed 5% concentration of calcite to enhance the shear strength of soft clay from Cihampelas, West Bandung. A series of laboratory tests, including triaxial shear tests, Atterberg limits, and compaction tests, were conducted with curing periods of 0, 3, 7, and 14 days. The results showed that the mixture containing 12% silica fume and 5% calcite, after 14 days of curing, provided the most significant improvement, with a cohesion value of 1.757 kg/cm² and an internal friction angle of 35.31°. In comparison, the untreated clay had a cohesion of 0.826 kg/cm² and an internal friction angle of only 9.90°. These findings demonstrate that the synergistic interaction between silica fume and calcite strengthens the bond between soil particles and significantly improves the soil's microstructure density. The research provides valuable insights for geotechnical engineering, particularly in the design of foundations and road pavements in areas with problematic clay soils.