Improvement of strength characteristics of lateritic sub-grade soil with shredded polyethylene waste

This paper presents the results of investigation of the behavior of pavement subgrade soil stabilized with shredded polyethylene waste. Shredded high density polyethylene High Density Polyethylene Waste of maximum size 20 × 25mm was used for the improvement of lateritic soil at various percentages which are; 1%, 2%, 3%, 4%, and 5% respectively. Series of laboratory tests such as, Compaction and California Bearing Ratio (CBR) were conducted to determine the influence of polyethylene waste on the lateritic soil. The results reveal that addition of polyethylene waste to the soil increased the optimum moisture content (OMC) but, reduced the maximum dry density (MDD) from 2338.60kg/m3 to 1941.64kg/m3. A decrease in the dry density of soil sample shows that low comparative energy would be required for the soil to attain its maximum dry density; as a result the cost of compaction is significantly reduced. Improvement in CBR values was also observed for laterite-polyethylene mixture; resulting in maximum CBR value of 13.18% under soaked condition. This value falls within the range of 10% to 25% CBR value specified for sub grade soils by the AASHTO standard and the Nigerian Highway Design Manual, Federal Ministry of Works and Housing. An increase in the California Bearing Ratio value can significantly reduce the total thickness of the pavement; hence, the total cost involved in the project. The strength of Lateritic clay subgrade soils can be improved with the addition of five percent (5%) Shredded high density polyethylene (HDPE) Waste of maximum size 20 × 25mm.Keywords: Lateritic soil, High density polyethylene (HDPE) waste, Pavement thickness, Sub-grade soi

NIGERIAN LATERITIC CLAY SOILS AS HYDRAULIC BARRIERS TO ADSORB METALS. GEOTECHNICAL CHARACTERIZATION AND CHEMICAL COMPATIBILITY

The suitability of using lateritic clays from Aviele and Igarra has been investigated both in the Northern part of Edo state, Nigeria as liners of an engineered landfill and to adsorb metals in leachates. Geotechnical characteristics, pH, and elemental composition for the lateritic clay samples were determined. The chemical composition, pH, total dissolved solids and electrical conductivity were determined for leachates collected from two dumpsites. The capacities of the lateritic clay soils to adsorb heavy metals in the leachates were determined using the batch equilibrium adsorption technique. The unconfined compressive strength (UCS) of soils were found to be sufficient to resist damage. By both the standard and modified Proctor compaction tests, it was found that the coefficients of permeability for the soil samples were lower than 1×10–9 m/s that is widely recommended for soils that are to be used as landfill liners. Pb2+, Zn2+ and Cr2+ were the heavy metals in the leachates. The sorption selectivity order for tested soils depended on the soil type and properties