An investigation of nonmagnetic iron slag effect on engineering parameters of expansive soil and its statistical validation

Soil is a surface material formed from the disintegration of rock under physical and chemical processes. Each soil has different characteristics because of the formation process. The soils are classified as cohesive and noncohesive soil based on their characteristics. The soil having more than 50% fine content is called expansive soil. The geotechnical improvement and handling of the expansive soil is challenging for geotechnical engineers. The present research improves the engineering parameters of expansive soil collected from the Talab, Nainwa, Bundi, using nonmagnetic iron (NMI) slag. For that purpose, 5–30% NMI slag was added at a 5% variation to analyze the effect of NMI slag on the engineering properties of soil. The laboratory investigation showed that the specific gravity of soil is increased by 18.36% by adding 30% NMI slag. Conversely, the swelling index of soil is decreased by 76% by adding 30% NMI slag. The plasticity index of soil is decreased by 16.84% with the addition of 30% NMI slag. The standard proctor test results, i.e., optimum moisture content (OMC) and maximum dry density (MDD), showed that the MDD of soil is increased by 18.62% by adding 25% NMI slag. Furthermore, the strength parameters, such as soaked CBR, unsoaked CBR, and unconfined compressive strength of soil, are increased by 57.17%, 105.28%, and 142.75%, respectively. The analysis of results showed a significant improvement in the engineering properties of expansive soil using the NMI slag. Also, it was found that the NMI slag improved the UCS of soil better than the copper slag, steel slag, and ground granulated blast furnace slag. In addition, the experimental results of the NMI slag stabilized soil were validated by statistical clauses of the ANOVA (F > F crit and p-value < 0.05) and T-test (p-one tail < p-two tail < 0.05, T-one tail < T-two tail < t state) and accepted the research hypothesis for this research.