A review of the mechanical and leaching performance of stabilised/solidified contaminated soils

Stabilisation/solidification (S/S) technology, which basically involves chemical fixation and immobilisation of contaminants, mainly metals, in the matrix of cementitious binders, is widely used for treatment of contaminated soils. This paper presents a critical review of the performance of commonly used blended binder systems in S/S technology. The binders considered are Portland cement, and cement-fly ash, cement-slag, lime-slag and lime-fly ash blends. This work compares and evaluates the performance of contaminated soils treated by the binders in terms of commonly used mechanical and leaching properties, including unconfined compressive strength (UCS), bulk density, hydraulic conductivity and leachability. The long-term performance of S/S treated soils is also reviewed. It was observed that the inclusion of slag in a binder blend gave superior performance compared to fly-ash. Generally, the leachability of common contaminants in soil can be reduced to acceptable levels with about 20 35% dosage of the different binders. The UCS was observed to be optimum around the optimum water content for compaction. The hydraulic conductivity generally fluctuated around 10 m/s over time. Long-term performance of treated soils showed consistent effectiveness over a period of 5 14 years with the occurrence of fluctuations in mechanical and leaching behaviour owing to the complex nature and variability of S/S treated soils. This is an author-created version of an accepted manuscript (post-print). A definitive version was subsequently published in the journal, Environmental Reviews. The full citation can be obtained using the article DOI: http://dx.doi.org/10.1139/er-2013-0004 A review of the mechanical and leaching performance 1 of stabilised/solidified contaminated soils 2 3 Reginald B. Kogbara 4 5 1 Geotechnical and Environmental Group, Department of Engineering, 6 University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK. 7 Present Address: Mechanical Engineering Program, Texas A&M University at Qatar, 8 P.O. Box 23874, Education City, Doha, Qatar. 9 *Email: [email protected] 10