Effect of Lime and Phosphogypsum on the Geotechnical Properties of Dispersive Soil

Dispersive soils are highly erodible and prone to segregation in water, posing significant risks to the soil and structural stability. Traditional stabilization methods using cement and lime are effective but raise sustainability concerns due to the high carbon emissions. This study explored the utilization of phosphogypsum (PG), a by-product of the fertilizer industry, as a sustainable alternative to improve dispersive soils. PG was evaluated both individually and in combination with lime, focusing on its effects on the plasticity, swell, consolidation, compaction, and unconfined compressive strength (UCS) characteristics. Soil samples were treated with varying proportions of lime (2–10%) and PG (2–10%). The results demonstrated that combining 4% lime with 8% PG significantly enhanced the properties of dispersive soil, reducing the swell pressure from 115 kN/m 2 to 72 kN/m 2 and the swell potential by 67%. The UCS increased by 320% after 7 days of curing, while the coefficient of consolidation improved 2.74 times and the compression index decreased by a factor of 8.55. Regression analysis was conducted and validated for UCS prediction. Utilizing PG not only improves the soil stability, but also offers a sustainable solution by recycling industrial waste and reducing the dependence on conventional materials. These findings underscore the potential of PG as an eco-friendly soil stabilizer for dispersive soils.