Effect of metakaolin and silica fume on the engineering properties of expansive soil

Abstract

Abstract Characteristics of the expansive soil should be studied due to the effects and problems of this soil on the structures that build on it, also, its spread in large areas in the world. Some of these problems are the cracks and large damages on the structures due to the differential settlement of the soil. These problems occur due to the swelling and shrinkage characteristics of the soil when it is affected by changeable water content. The need for the stabilizers to overcome these problems appears due to a large amount of loses money caused by the expansive soil’s problems. This study used silica fume and metakaolin which considers stabilizer agents that used to treat the expansive soil. Silica fume is an industrial material obtained by condensation operation to the smoke that produced from the production process of the ferrosilicon metal. While metakaolin is a a pozzolanic material obtained from the burning of kaolin rock to (700-800) °C. The soil used in this study classified as CH soil. The treated samples were prepared by mixing the soil with (5%, 10%, and 15%) of the two additives. From the results, it was found that Atterberg limits were increased with the adding silica fume and decreased with Metakaolin. Specific gravity decreased with silica fume while it is increased with Metakaolin. The maximum dry unit weight decreased, and the optimum water content increased with silica fume and the opposite occur with metakaolin. The results showed that the swelling present improved with both additives.