Amelioration Effect of Fly Ash and Powdered Ground Steel Slag for Improving Expansive Subgrade Soil

Abstract

The utilization of fly ash (FA) and powdered granulated steel slag (PGSS) as additives in soil stabilization plays a crucial role in environmental, economic, and weak soil property improving advantages. In this study, the combined effect of FA and PGSS in improving expansive subgrade soil was investigated. The materials used for this study were expansive soils, FA, and PGSS. The study has applied an experimental research method. For this investigation, the index properties, Free Swell Index (FSI), unconfined compressive strength (UCS), optimum moisture content (OMC), California bearing ratio (CBR), and scanning electron microscope (SEM) tests were done for treated and untreated expansive soils. The findings indicated that as the mixture of FA (0 to 12.5% at 5% increment) and PGSS (0 to 25% at 5% at 2.5% increment) is added to the untreated expansive soils, the index properties, FSI, and OMC of the soils were significantly declined. The CBR values of expansive soils containing 20% FA and 10% PGSS mixture were 13.8% and 16.21%, respectively, which improved the quality of the soils by 85.43% and 84.82%, respectively. While the untreated expansive soils have a UCS value of 0.34 kg/cm2, the treated soil comprising 20% FA and 10% PGSS mixture has a UCS value of 13.42 kg/cm2, indicating that the soil strength is enhanced by 97.47%. The results of the studies demonstrate that adding FA and PGSS to expansive soil improves its stability and strength. The study concluded that disposals such as FA and PGSS might be effectively used in enhancing the characteristics of construction materials and used for the construction.