Engineering Properties of Heavy Metal Contaminated Soil Solidified/Stabilized with High Calcium Fly Ash and Soda Residue

Both high-calcium fly ash and soda residue are the industrial by-products generated during the combustion of coal for energy production and sodium carbonate production, respectively. Previous studies suggested that both high-calcium fly ash and soda residue can be used to treat heavy metal contaminated soils. Therefore, a series of laboratory experiments were performed to investigate the strength and leaching properties of Pb-contaminated soils solidified/stabilized by high calcium fly ash and soda residue. The results presented that adding high-calcium fly ash to the contaminated soils can significantly improve the soil strength and reduce the Pb2+ amount released out. The specimens treated with soda residue got a higher strength, but a relatively lower chemical stability than that of fly ash. SEM results confirmed that Ca(OH)2 and CSH was the main products that improved the engineering properties of the stabilized contaminated soils.