Effect of Curing Age on the Prospect of Used Plastics to Enhance Engineering Properties of Road Pavements within a Development and Property Agency Estate in Benin City, Edo State, Nigeria

Abstract

This study investigated the effect of curing age on the possibility of using plastic powder to enhance the engineering properties of subgrade for road pavements. The soil samples utilized for the study were collected from four distinct locations within the Edo Development and Property Agency estate in Benin City, Edo State, Nigeria using appropriate standard methods. They were stored in airtight polythene bags and taken to the University of Benin Geotechnical Laboratory for testing. Polyethylene terephthalate (PET) plastics sourced from recycled soft drink and bottled water containers were pulverized and added to the soil in various proportions of 2%, 4%, 6%, 8% and 10% by weight of the soil. The resulting mix was subjected to various tests such as Atterberg limits, compaction and California Bearing Ratio (CBR). The results showed that the addition of the PET plastic powder led to substantial transformation in the soil’s properties. There was a reduction in the liquid limit, plastic limit and plasticity index, as the proportion of the plastic powder increased. The maximum dry density (MDD) and the optimum moisture content (OMC) was also seen to increase and decrease correspondingly as the proportion of the plastic powder was increased in the soil. The results also showed that as proportion of the plastic powder in the soil was increased, the CBR of the soil also increased. This increase in the soil strength was also observed as the curing age of the CBR samples increased from 0 to 14 days. This shows that a combination of extended curing periods and a larger proportion of plastic powder can significantly improve the load-bearing capacity and saturation resistance of the soil. This study underscores the considerable potential of plastic powder stabilization in elevating the engineering properties of subgrade materials, thereby conferring notable benefits to the domain of road pavement construction.