Enhancement of the Strength and Permeability Properties of an Expansive Soil Using Chopped Basalt Fibers and Silica Fume

Clays are soils that display plastic behaviors, have substantially lowered strength at high water content values, and can show significant subsidence. To construct on these soils, the engineering properties of the ground need to be improved. The engineering properties of clayey soils can be improved using chemical additives such as cement, lime, silica fume, and fly ash. Additionally, in recent years, the number of studies on the use of fibers in soil improvement has been increasing. In this study, the effects of basalt fiber and silica fume additives on the strength and permeability properties of problematic soil were investigated. For this purpose, varying values of basalt fiber length (6–24 mm), basalt fiber content (0–1.5%), curing time (1–56 days), and silica fume content (0–15%) were selected. Experiments were conducted using the Taguchi method with an L16 orthogonal array with 4 parameters and 4 levels. Specimens that were prepared at the optimum water content and maximum density values were subjected to unconfined compression, splitting tensile, and permeability tests. According to the results of the statistical analyses, the optimum parameters for the unconfined compressive strength and splitting tensile strength experiments were determined as a basalt fiber length of 18 mm, a basalt fiber content of 1%, a silica fume content of 10%, and a curing time of 56 days. As the length and content of basalt fibers increased, the permeability coefficient of the material also increased. On the other hand, the permeability coefficient of the material decreased when the silica fume content increased.