Improvement of Subgrade Characteristics Using Waste Plastic Bottle

Abstract

The need to improve the strength and durability of subgrade soil in recent times has become imperative using stabilizing materials that can be sourced locally at no/or very low cost in other to reach their design life span before a major repair is required. This necessitates the improvement that could be achieved by stabilizing subgrade soil along Ede-Abeere road in Ede, Osun State with the Waste Plastic Bottle (WPB). The soil samples were collected at 1m depth at different portions along the road and stabilized with varying percentages of WPB. Laboratory tests conducted were sieve analysis, natural moisture content, specific gravity, Atterberg limit, compaction, California Bearing Ratio (CBR), and Unconfined Compressive Strength (UCS) Test. The CBR of the stabilized soil ranges from 1.28% to 12.20% with 2.5% WPB having the highest CBR value of 12.20% meeting the recommended value for unsoaked CBR of subgrade soils. However, the statistical model reliably adjudged that there is a significant relationship between the CBR values of subgrade soil-WPB mixture obtained. Thus, it is recommended that WPB at 2.5% can serve as a stabilizing material as it increases the CBR of the subgrade soil and as an effective method of disposing of WPB.