Behaviour of Lime-stabilised Lateritic Soil Reinforced with Plastic Waste

The increasing demand for sustainable infrastructure development has intensified research into the use of alternative and waste-derived materials in geotechnical engineering applications. Lateritic soils are widely used as subgrade and subbase materials in tropical regions; however, their engineering properties are often inadequate for heavy traffic loading without stabilisation. Lime stabilisation has been extensively adopted to improve the strength and durability of such soils, while the incorporation of waste plastics offers an environmentally sustainable solution to the growing challenge of plastic waste disposal. This study therefore investigates the behaviour of lime-stabilised lateritic soil reinforced with plastic waste, with particular emphasis on strength.
To achieve the aim of the study, lateritic soil samples were collected from two selected borrow pit. Thee soil samples were subject to preliminary and geotechnical tests, using standard procedure. The soil samples were then treated with varying proportions (2 %, 4 % and 6 % by weight of dry soil) of hydrated lime and subjected to California Bearing Ratio (CBR) test. The soil-lime composition that gave the highest CBR values was subsequently reinforced with shredded plastic waste (SPW) in proportions of 1 %, 2 % and 3 % by weight of dry soil-lime material, and subjected to CBR test. Results showed that 6 % lime stabilisation gave the best improvement in the strength of tested soils. Reinforcement of soil-lime composition with SPW led to further improvement in the strength of stabilised soils, with the highest SPW proportion yielding the highest CBR values; that is, the optimum SPW proportion was not attained in the study. The study concludes that reinforcement of lime-stabilised soil with SPW does not adversely affect the strength; rather, it leads to further improvement in soil strength.