Compacted black cotton soil treated with cement kiln dust as hydraulic barrier material

Abstract

Laboratory tests were conducted on black cotton soil treated with up to 16% Cement Kiln Dust (CKD) by dry weight of soil to assess its suitability for use in waste containment application. Specimens were prepared at molding water contents -2%, 0%, +2% and +4% of the optimum moisture content at the compactive energy levels of British Standard Light (BSL) and West African Standard (WAS). Index properties, hydraulic conductivity (k), volumetric shrinkage strain (VSS) and unconfined compressive strength (UCS) tests were carried out. Results obtained showed slight changes in index properties. Hydraulic conductivity values recorded at both BSL and WAS produced satisfactory results that met the regulatory 1x10 -9 m/s requirement at all treatment levels. The UCS values after 4% CKD treatment especially at WAS compactive energy level met the minimum regulatory value of 200kN/m 2 for shear strength. VSS values recorded met the regulatory requirement of less than 4% volumetric shrinkage strain at 16% CKD content for BSL and 12 and 16% CKD contents for WAS energy level. The overall acceptance zone for CKD treated black cotton soil was achieved at 12 and 16% cement kiln dust content for specimen prepared at molding water content range of 16.7-21.6% and 17.2-19.3 % respectively.