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.

This research examines the shear strength of Sisal Fibre Reinforced Concrete (SSFRC).Sisal Fibre (SSF) addition was at 1% by weight of dry constituents, this is considered the upper limit for workable mixes in the absence of water reducing agents. Beams of various grades of concrete (20N/mm 2 to 40N/mm 2 ) were tested and they all failed in shear. Experimental results of beams were compared with modified versions of the BS 8110 formula for shear strength in concrete, to determine the best fit. The inclusion of SSF at 1% addition increased the compressive strength of the concrete mix by an average of 16.9% and the shear strength by 16%. However, the shear strengths of the SFRC are only greater than those of normal concrete of corresponding compressive strengths by 9.5%. The equation proposed may be used to estimate the shear strength of SSF reinforced concrete at this level of fibre addition.

Organisms or chemicals introduced into soils for soil improvement tend to make such soil reactive and this may affect the parameters that are used to determine the engineering and other properties of the soil. In this study, the electrical resistivity of Bacillus pumilus microbial-induced calcite precipitate-treated lateritic soil at different compactive effort was evaluated; lateritic soil was treated with stepped densities of B. pumilus suspensions of 0/ml, 1.5 × 10 8 /ml, 6.0 × 10 8 /ml, 12 × 10 8 /ml, 18 × 10 8 /ml and 24 × 10 8 /ml, respectively, and compacted with three compaction energies, namely British Standard Light (BSL), West African Standard (WAS) and British Standard Heavy. The treated soil samples were cured for 7, 28 and 56 days to also see the effect of the curing period on the resistivity of the treated lateritic soil. The resistivity test result shows an increase in resistivity value with an increase in B. pumilus suspension density and also with an increase in compactive energy. Though there is a marginal increase between BSL and WAS compactive effort. The peak resistivity value was obtained at 2.4 × 10 9 cells/ml of B. pumilus suspension density for all compactive effort considered. The effect of curing days indicates that beyond 28 days there is only a marginal increase in resistivity value because there is little or no increase in the resistivity values obtained.

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