Thi Thi Thi This s s s study wa study wa study wa study was carried out to evaluate the effect of bagasse ash s carried out to evaluate the effect of bagasse ash s carried out to evaluate the effect of bagasse ash s carried out to evaluate the effect of bagasse ash on the California bearing ratio of lateritic soil. on the California bearing ratio of lateritic soil. on the California bearing ratio of lateritic soil. on the California bearing ratio of lateritic soil. Laboratory tests were performed on the natural and bagasse ash treated soil samples in accordance with BS 1377 Laboratory tests were performed on the natural and bagasse ash treated soil samples in accordance with BS 1377 Laboratory tests were performed on the natural and bagasse ash treated soil samples in accordance with BS 1377 Laboratory tests were performed on the natural and bagasse ash treated soil samples in accordance with BS 1377 (1990) and BS 1924 (1990) respectively. Treated specimens were prepared by mixing the soil wi (1990) and BS 1924 (1990) respectively. Treated specimens were prepared by mixing the soil wi (1990) and BS 1924 (1990) respectively. Treated specimens were prepared by mixing the soil wi (1990) and BS 1924 (1990) respectively. Treated specimens were prepared by mixing the soil with th th th bagasse ash in bagasse ash in bagasse ash in bagasse ash in steps of 0, 2, 4, 6 and 8 % by weight of dry soil steps of 0, 2, 4, 6 and 8 % by weight of dry soil steps of 0, 2, 4, 6 and 8 % by weight of dry soil steps of 0, 2, 4, 6 and 8 % by weight of dry soil and contaminating it with used oil in steps of 0, 2, 4, and 6 % by and contaminating it with used oil in steps of 0, 2, 4, and 6 % by and contaminating it with used oil in steps of 0, 2, 4, and 6 % by and contaminating it with used oil in steps of 0, 2, 4, and 6 % by weight of dry soil weight of dry soil weight of dry soil weight of dry soil. The preliminary. The preliminary. The preliminary. The preliminary laboratory laboratory laboratory laboratory investigation carried out on the natural lateritic soil shows that it investigation carried out on the natural lateritic soil shows that it investigation carried out on the natural lateritic soil shows that it investigation carried out on the natural lateritic soil shows that it fall fall fall falls under Silt s under Silt s under Silt s under Silt-Clay material of Group A Clay material of Group A Clay material of Group A Clay material of Group A-6 using AASHTO classification and inorganic clay material 6 using AASHTO classification and inorganic clay material 6 using AASHTO classification and inorganic clay material 6 using AASHTO classification and inorganic clay material of low to of low to of low to of low to medium plasticity medium plasticity medium plasticity medium plasticity CL according to Unified Soil Classification System (USCS). The specific gravity of the soil samples CL according to Unified Soil Classification System (USCS). The specific gravity of the soil samples CL according to Unified Soil Classification System (USCS...

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A reddish-brown lateritic soil obtained from Zaria; Nigeria was treated with up to 2.5% nano-silica. Consolidation properties (i.e. Pre-consolidation pressure, compression index, coefficient of volume compressibility and coefficient of consolidation) of treated specimens were assessed using one dimensional consolidation test. The permeability property of treated soil was also evaluated. The results obtained showed that the pre-consolidation pressure generally increased with increasing percentage of nano-silica content and curing time. The compression index (Cc) increased steadily with higher percentage of nano-silica contents up to 2.5% treatment for 7 and 14 days of curing, but decreased after 28 days curing period. The recompression index (Cr) on the other hand generally increased with increase percentage of nano-silica content and curing period. The coefficient of volume compressibility (Mv) did not follow any definite trend, but at 2.5% nano-silica content, the Mv decreased for all curing periods considered. The coefficient of consolidation (Cv) also, did not give a definite trend with increase in nano-silica content, suggesting that increasing the amount of nano-silica content in the soil has little or no impact on the time rate of settlement. The coefficient of permeability (k) decreased as the soil was treated with nano-silica especially beyond loading pressure of 40kN/m2. This study showed that nano-silica (up to 2.5%) can be used to stabilize lateritic soil to improve its consolidation properties.

This study was carried out to evaluate the effect of spent oil contamination on the strength of lime stabilized soil. Laterite soil was stabilized with lime in percentages of 0, 2, 4, 6, and 8% of the dry weight of soil. Specimens were prepared for UCS and CBR. The specimens for UCS were cured for 7, 14 and 28 days; while the specimens for CBR were cured for 4 days. Contamination of the specimens was achieved by soaking in spent oil medium in a plastic bowl for 48 hours after the respective curing periods. The uncontaminated soil and the contaminated soil were both tested for UCS and CBR. The results obtained show that the strength of lime stabilized soil decreased when contaminated with oil. The value of the UCS decreased by about 46, 23 and 13% on the average for soil-lime mixture cured for 7, 14 and 28 days, respectively. Similarly, the CBR of the soil-lime mixture reduced by about 35%. It was also observed that the resistance to loss in strength increased with lime content and curing period. This results show for all practical purposes that a lime stabilized pavement structure exposed to oil contamination is susceptible to failure as a result of reduction in strength and bearing capacity due to oil contamination.

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