Effect of Oil Contamination on Lime Stabilized Soil

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

Assessment of Bagasse Ash Effect on the California Bearing Ratio of Used Oil Contaminated Lateritic Soils

This study was carried out to evaluate the effect of bagasse ash 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 (1990) and BS 1924 (1990) respectively. Treated specimens were prepared by mixing the soil with bagasse ash in 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 weight of dry soil. The preliminary laboratory investigation carried out on the natural lateritic soil shows that it falls under Silt-Clay material of Group A-6 using AASHTO classification and inorganic clay material of low to medium plasticity CL according to Unified Soil Classification System (USCS).  The specific gravity of the soil samples decreased from 2.61 for the natural soil to 2.48 at 8 % bagasse ash content and to 2.16 and 2.11 at 6 %oil / 0 %BA and 6 %oil / 8 %BA contents respectively. The liquid and plastic limits increased from 36.32 and 21.30 % respectively to peak values of 38.00 and 21.54 % at 2 % bagasse ash content for all oil contents. The maximum dry density (MDD) of the soil increased from 1.48 Mg/m3 for the natural soil to peak value of 1.49 Mg/m3 at 8 % bagasse ash content for all oil contents. The Optimum Moisture Content (OMC) increased from a value of 18.5 % for the natural soil to 19.0 % at 2 and 4 % bagasse ash contents and then after decreased. The unsoaked California bearing ratio values from 4 %BA content and above met the minimum CBR value of 30% specified by (BS 1990) for materials suitable for use as base course material when determined at MDD and OMC. However, the highest CBR value of 62 % recoded at 8 % BA content failed to meet the 80 % CBR value recommended by the Nigerian general specification (1997) for cement stabilization. Oil contamination resulted in reduced CBR values (strength) in lateritic soils.http://dx.doi.org/10.4314/njt.v34i2.

Cement stabilisation of crude-oil-contaminated soil

© 2016, Thomas Telford Services Ltd. All rights reserved. Crude-oil-contaminated soils are usually considered unsuitable construction materials for earthworks. This paper presents an experimental investigation of the effects of applying Portland cement on the plasticity, strength and permeability of a crude-oil-contaminated soil in order to ascertain its suitability for use as an earthworks construction material. Series of specific gravity, Atterberg limits, compaction, strength and permeability characteristics were determined for a natural soil, the soil after being artificially contaminated with crude oil and the contaminated soil with varying proportions of added cement. It was found that the geotechnical properties of the soil became less desirable after contamination with crude oil, but the application of cement to the contaminated soil improved its properties by way of cation exchange, agglomeration and cementation. Cement stabilisation of crude-oil-contaminated soil provides a stable supporting structure, as well as a capping layer, that prevents the crude oil from interacting with the construction materials above. Thus, instead of disposing of contaminated soils, creating unnecessary waste and incurring costs, stabilisation with cement – which is practically feasible to undertake on site – makes such soils useful for supporting structural foundations or road pavement structures