Performance of Lime-Treated Sandy Soils after Sustainable Reinforcement Using Waste Plastic Fibre

Abstract

Subgrade soil is a natural formation utilised as a foundation for pavement layers, which means that it must be strong enough to support the pavement system. Subgrades such as loose sand, clay and silt soils thus need to be stabilised in order to improve in-situ performance. Several different geotechnical techniques have been utilised for soil stabilisation, and in this research, experimental work was carried out to examine the use of hydrated lime and waste plastic fibre as sustainable additives to enhance the characteristics of loose subgrade sand. The hydrated lime was added at several different percentages (4, 6, 8, and 10% by dry weight of soil), and the laboratory tests results revealed that adding 8% lime to the soil provided the best strength characteristics. The optimum lime-treated sandy soil was then reinforced by the addition of waste plastic fibre with lengths ranging from 5 to 20 cm added at three percentages (1, 2 and 3% by dry weight of soil). The dynamic behaviours of the reinforced stabilised soil in terms of surface deflection and dynamic modulus were evaluated using a light weight deflectometer test (LWD). The results illustrated that adding 10 cm waste plastic fibre at 3 wt.% content led to an increase in the dynamic modulus of 28.12% and a decrease in the surface deflection of 21.35% as compared to natural subgrade soil.