SUSTAINABLE STONE COLUMNS: PERFORMANCE ASSESSMENT OF JAROSITE AND COAL MINE WASTE IN SOFT SOIL STABILIZATION

The sustainable management of industrial byproducts is a growing necessity in geotechnical engineering. This study investigates the feasibility of utilizing coal mine waste (CMW), jarosite waste (JW), and natural aggregates (CA) in combination for constructing stone columns aimed at ground improvement in weak clayey soils. Three mix ratios—M1 (30% CMW, 20% JW, 50% CA), M2 (40% CMW, 30% JW, 30% CA), and M3 (50% CMW, 30% JW, 20% CA)—were prepared and treated with lime and fly ash to mitigate acidity and enhance pozzolanic reactions. Laboratory and field-scale tests, including modified Proctor compaction, plate load testing, California Bearing Ratio (CBR), and triaxial shear tests, were conducted to evaluate compaction characteristics, load-bearing capacity, and settlement reduction performance. Results showed that the M2 mix achieved the highest performance, with a 2.3-fold increase in ultimate bearing capacity, 52% settlement reduction, and a two- to three-fold improvement in CBR compared to untreated soil. Strength enhancements were attributed to the synergistic effects of granular interlock from coal mine waste, binding properties from stabilized jarosite, and structural integrity from aggregates. Environmental leaching analyses confirmed that lime and fly ash treatment effectively immobilized heavy metals, making the material safe for geotechnical applications. the research highlights that the engineered use of jarosite and coal mine waste, under controlled stabilization, enables the development of sustainable and high-performance stone columns, reducing reliance on natural aggregates.