Silica Fume Influence on Behavior of Expansive Soil

In this investigation, silica fume (SF) was used as an additive material to study its influence on the characteristics of expansive soil. The soil used in this research was prepared in a lab by mingling bentonite (50 percent by soil dry weight) with natural soil. According to (USCS), the prepared soil was classified as (CH) with a liquid limit of 67.5 percent and a plastic limit of 29.3%. Expansive soil was mixed with different percentages of (SF), (8, 9, 10, 11, 12, and 13%), and experiments were conducted for treated and untreated soil to examine the impact of (SF) on Atterberg's limits, compressibility, swelling, and shear strength parameters. The outcome of this test shows that the use of silica fume raised Atterberg's limits (L.L, P.L, and P.I) and lowered compressibility and swelling percentage, as well as shear strength parameters (c,φ), were altered by increasing the angle of internal friction (φ), and decreased the cohesion (c). From these results, it is concluded that (SF) has a positive effect as an additive material to enhance the geotechnical properties of expansive soil.