Abstract

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This study examines the influence of compactive efforts on the geotechnical properties of compacted black cotton soil treated with metakaolin (MTK) to assess its suitability for use as a barrier material in waste containment application. Black cotton soil treated with up to 10% MTK (obtained from calcinations of kaolin) by dry weight of soil was used. The natural soil classifies as A-7-6(22) and Clay with high Plasticity CH according to American Association of State Highway and Transportation Officials AASHTO and Unified Soil Classification System USCS respectively. The laboratory result obtained showed that there was a significant improvement in some of the geotechnical properties of the soil. The liquid limit and plastic limit decreased from 50 and 27.38% for the natural soil to 47.1 and 16.7 % when treated with 10 % metakaolin while the plasticity index increased from 22.59 % for the natural soil to 30.93% when treated with 10 % metakaolin content The hydraulic conductivity value decreased from 1.91 x 10-8 , 1.81 x 10-8 and 1.72 x 10-8 to 0.38 x 10-8 , 0.66 x 10-8 and 0.66 x 10-8 cm/sec for the three compactive efforts of British Standard Light (BSL), West Africa Standard (WAS) and British Standard Heavy (BSH) respectively. It was recommended that MTK treated black cotton soil could be used as a liner or cover material in waste containment facilities.

Keywords: metakaolin treatment, black cotton soil, hydraulic conductivity, compactive efforts.