Papers by Author: Thomas Stephen Ijimdiya

Abstract: This paper presents the results of an evaluation of lime treated oil contaminated soil for use in waste containment systems. Soil samples were treated with up 6 % lime contents. Specimens were prepared at optimum moisture content and compacted using British Standard Light (BSL) or Standard Proctor (relative compaction = 100%) to evaluate its effectiveness when used in waste containment applications. The hydraulic conductivity values increased with higher lime contents but were less than 1 x 10^-9 m/s required for a liner material.

Abstract: Oil contaminated soils (PCS) was treated with up to 6% rice husk ash (RHA) by dry weight of soil. Specimens of treated soil compacted at the energy of the standard Proctor (relative compaction = 100%) were subjected to compaction, unconfined compressive strength (UCS) and California bearing ratio (CBR) tests. The results of laboratory tests show that properties of the treated soil improved with RHA treatment. Peak unconfined compressive strength value of 410kN/m2 was obtained at 2% oil/ Applying the conventional evaluation criteria reveals that soil-oil RHA mixture containing 2% oil/4% RHA, 4% oil/4% RHA and 6% oil/4% RHA yields optimum CBR values of 4.6, 4.4 and 3.5% which does not satisfy the minimum required CBR of 15% for use as a subgrade material in road foundation.

Abstract: Large quantities of oil contaminated soils result from pipeline vandalization, onshore and offshore oil spills every year in Nigeria. An extensive laboratory program was carried out to determine the effect of varying compactive efforts on the hydraulic conductivity behaviour of oil contamination lateritic soils. Hydraulic conductivity tests were carried out on both the natural and oil contaminated soil samples at the Reduced British Standard Light (RBSL), British Standard Light (BSL), West African Standard (WAS) and British Standard Heavy (BSH) compaction energies. Contaminated specimens were prepared by mixing the lateritic soil with maximum 6 % oil concentration by weight of dry soil. The results obtained indicated a decrease in the hydraulic conductivity of the contaminated soil samples with increasing compactive efforts.

Abstract: This paper presents the results of a laboratory study on the effect of oil contamination on the particle size distribution and plasticity characteristics of lateritic soil. The soil was artificially contaminated with a maximum 6 % oil content by weight of dry soil. The results show that there was a substantial reduction in the amount of fines content with higher amounts of oil in the soil matrix. The percentage of fine fraction in the natural soil was 86.9 % and on contamination with maximum 6 % oil content by weight of dry soil at optimum moisture content (OMC) the fine fraction reduced to 1.4 %. The plasticity index decreased from 16.0 to 8.5 % when contaminated with 6 % oil content by weight of dry soil. The plasticity modulus (PM), plasticity product (PP), the shrinkage modulus (SM) and the grading modulus (GM) decreased with increasing amounts of oil content.

Abstract: Laboratory studies to investigate the effect of Bagasse Ash (BA) admixture on the engineering properties of lime treated black cotton soil was carried out. Black cotton soil is classified as A-7-6 or CH respectively. Bagasse ash is obtained from burning the fibrous residue from the extraction of sugar juice from sugarcane. The results obtained show that the moisture density relationship follows a trend of increasing optimum moisture content (OMC)/decreasing maximum dry density (MDD) at the Standard Proctor compaction energy. California bearing ratio (CBR) values obtained are lower than the 80% CBR criterion for untreated base course materials. The peak CBR value obtained was 31% at 8 %lime/ 4%BA. This value meets the recommended criteria for subgrade materials. The Unconfined compressive strength (UCS) at 7 days is lower than the 1034.25kN/m2 evaluation criterion for adequate lime stabilization. On the basis of the soaked CBR and durability values, it is recommended that black cotton soil can be stabilized for road construction using a 8 % lime/ 4 % BA blend of admixture at standard proctor compaction. However, due to the relative high cost of lime and large quantity that shall be required to achieve stabilization, further study and consideration should therefore be given to the use another additive such as cement to augment and lower the percentage of lime and thus the cost of stabilization.