Stabilization of expansive soils using nontraditional chemical additives

Abstract

The aim of this study is to analyze the stabilization effects of an expansive soil using three different nontraditional chemical additives, in this case: white cement and nano-silica as admixture, waste granite dust, and a new liquid polymer soil stabilizer (i.e. liquid granite). The engineering properties such as soil consistency, linear shrinkage and soil swelling behaviour of a bentonite treated with these stabilizing agents were investigated. Furthermore, the bearing capacity of the stabilized bentonite was analyzed through the California Bearing Ratio test (BCR) and a laboratory foundation model. The experimental program consisted of three series of tests. In the first series, the tests were performed on an expansive soil reinforced with 2%, 4%, 8%, and 10% of white cement combined with 2% of nano-silica. Another series of tests consisted of samples mixed with different percentages of granite powder (5%, 10%, 15%, and 20%). In the third series, liquid granite as a soil stabilizer was blended with soil specimens at various concentrations (1%, 2%, 3%, and 4%). For all admixtures, the results showed a marked improvement in soil consistency, an important decrease in linear shrinkage, a considerable reduction on the expansion index, and a significant improvement of CBR and soil bearing capacity. Moreover, two empirical correlations were proposed between the bearing capacity parameters (i.e. CBR and Improvement factor) and the expansion index.