Utilizing expansive soil treated with phosphogypsum and lime in pavement construction

Abstract

This study investigated the use of phosphogypsum (PG) in the long term as a construction material, especially in pavement structures. This study aimed to investigate the effect of increasing PG percentages on the geotechnical parameters of Expansive Soil. Extensive laboratory tests were conducted on both natural and PG-stabilized soil mixtures to examine their compaction properties, consistency limitations, swelling and linear shrinkage, pH values, and unconfined compressive strength (UCS), California bearing ratio (CBR), scanning electron microscopy (SEM), and X-ray Diffraction (XRD). The results showed that the PG addition would significantly reduce soil plasticity, linear shrinkage, and swell potential. Despite these improvements, the study concluded that treating the soil using PG only did not affect its physical properties sufficiently to be considered as a pavement subbase. As an alternative, lime was supplemented to the soil-PG mixture and noticed that a blend of 30% PG and 4% lime significantly improved soil strength, thereby rendering it appropriate for utilization as a pavement subbase layer. The Mechanistic-Empirical Pavement Design Guide (MEPDG) was utilized to assess the performance of pavement sections formed with PG-treated and untreated soils. As a result, this study contributes to the development of an environmentally sustainable PG waste management system while also demonstrating its potential uses in roadway construction.

Keywords

• California bearing ratio (CBR)
• Expansive soils
• Mechanistic-empirical pavement design guide (MEPDG)
• Phosphogypsum (PG)
• Soil stabilization
• Sustainable construction materials