The soil improvement is one of the basic requirements for preparing the in situ soils for appropriate strengthening, stiffness and stability in civil engineering designs and applications.The modification technique which involves mechanical, thermal and chemical approach requires monitoring techniques to determine their efficiency and suitability. This study examined the geotechnical improvement of clay soils using the lime pile technique on a laboratory scale model. With this view, the clay-lime physicochemical reactions resulted from cation exchange was examined through basic experimental analyses. In addition, electrical conductivity measurements were determined on the selected treated soils to examine variations in their electrical properties. Remolded compacted clay soil blocks were carefully prepared in circular steel test tanks with lime piles installed in them. As such, the treated soil block properties were investigated as a function of radial lime pile distances and curing periods. It has been observed that there are significant changes in the Atterberg limit, linear shrinkage, compaction characteristics and strength of the treated soils due to the clay-lime reactions. The results indicated that these reactions have remarkable effects on the electrical properties of the lime pile treated soil and produced strong inter-particle bond and unconfined compressive strength of the soil. This is attributed to the migration of Ca 2+ and Mg 2+ ions from the lime piles into the soil, flocculation of particles and pozzolanic reactions. The significant changes in the electrical property and shear strength values suggested that their correlative changes can be used as a monitoring technique to determine the improvement in the geotechnical properties of chemically treated soils.

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This study attempted to synthesize and characterize engine oil additives from plastic waste, i.e., low density polyethylene, high density polyethylene, and poly propylene for the purpose of improving the viscosity index and pour point of engine oils. To do this, the starting polymers were reacted with maleic anhydride in a chain growth addition polymerization. The reactions took place in a muffle furnace at 230°C. The product poly (alkenymaleic anhydride) was then reacted with a glycerol at 140°C in a step growth addition polyesterification in the presence of xylene and nitrogen. The product formed, i.e., monoester acid, was then reacted with diethylene triamine in a step growth condensation polyamidation to produce the additive. The results obtained showed that the utilization of the additive produced from poly propylene as an additive on the base oils, i.e., SN150, SN500, BS 150 and commercially available oil (YT3513), gave the best results. The optimum blending concentration of 60 g/dl was achieved for the base oils except BS 150, which was 50 g/dl. Results also indicated that the optimum weight percentage of the blended additives was 3 wt%, while the optimum viscosity index was 162, 160, 159, and 186 corresponding to an increment of 80, 64.42, 36.76, and 36. 76% for SN150, SN500, BS150, and YT3513, respectively.

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Electrokinetic (EK) treatment is an innovative, cost-effective in situ ground modification technology. The EK treatment uses a combination of low-voltage direct-current, electrodes, and ionic solutions across problematic soil to improve the ground conditions. This study aims to model the effect of changing electrode length (le) on the performance of the EK treatment on the engineering properties of fine-grained problematic soils. The consideration of the changing electrode lengths (le), varying soil depths (ds), and lengthwise anode to cathode distances (dA↔E), in the soil block samples, is in the form of the laboratory model test tank. The significant performance of the experimental tests was with changing electrode lengths of 0.25le (7.5 cm), 0.50le (15.0 cm), 0.75le (22.5 cm), and 1.0le (30.0 cm). The study analyzed the test data obtained from the Atterberg limit and one-dimensional swelling tests at different extraction points of the EK treated soils in the test tanks. Furthermore, the study carefully analyzed the effect of changing electrode length (le) on the performance of the EK treatment. The results of the Design of Experiment (DOE) model analysis revealed that the effect of changing electrode length (le) on the plasticity index (PI), and swelling potential (SP) of the EK treated soils, was significant. For a specific soil depth (ds), the electrode lengths (le) of 0.50le and 0.75le were significantly effective in reducing the PI, and the SP of the EK treated soils. Unlike other studies in the literature, the use of DOE analysis in the present study enabled the detection of the significant input factors and their interactive effects on the PI and the SP, thus, enabling the practicing engineers to navigate accurate design models for large in situ applications.