Time-dependent performance of soil mix technology stabilized/solidified contaminated site soils.

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Wang, Fei 
Wang, Hailing 
Al-Tabbaa, Abir 

This paper presents the strength and leaching performance of stabilized/solidified organic and inorganic contaminated site soil as a function of time and the effectiveness of modified clays applied in this project. Field trials of deep soil mixing application of stabilization/solidification (S/S) were performed at a site in Castleford in 2011. A number of binders and addictives were applied in this project including Portland cement (PC), ground granulated blastfurnace slag (GGBS), pulverised fuel ash (PFA), MgO and modified clays. Field trial samples were subjected to unconfined compressive strength (UCS), BS CN 12457 batch leaching test and the extraction of total organics at 28 days and 1.5 years after treatment. The results of UCS test show that the average strength values of mixes increased from 0-3250 kPa at 28 days to 250-4250 kPa at 1.5 years curing time. The BS EN 12457 leachate concentrations of all metals were well below their drinking water standard, except Ni in some mixes exceed its drinking water standard at 0.02 mg/l, suggesting that due to varied nature of binders, not all of them have the same efficiency in treating contaminated soil. The average leachate concentrations of total organics were in the range of 20-160 mg/l at 28 days after treatment and reduced to 18-140 mg/l at 1.5 years. In addition, organo clay (OC)/inorgano-organo clay (IOC) slurries used in this field trial were found to have a negative effect on the strength development, but were very effective in immobilizing heavy metals. The study also illustrates that the surfactants used to modify bentonite in this field trail were not suitable for the major organic pollutants exist in the site soil in this project.

Field trials, Modified clay, Novel binders, Soil stabilization, Aluminum Silicates, Clay, Construction Materials, Industrial Waste, Magnesium Hydroxide, Magnesium Oxide, Metals, Heavy, Soil, Soil Pollutants, Waste Management
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J Hazard Mater
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Elsevier BV
This paper was written to support the SMiRT (soil mix remediation technology) project, the funding for which was supplied by the UK Technology Strategy Board with 16 industrial partners (Project TP/5/CON/6/I/H0304E). The project website is at http://www-g.eng.cam.ac.uk/smirt. The authors are grateful to Schlumberger Foundation for its financial help of the PhD studentship for the first author, and many thanks to the proofreading by Fei Jin and David O’Connor.