The application of polymer coated aggregates in flexible pavement

The road construction industry in Mauritius has experienced a boom continuously for the past five to eight years to date. Moreover, since existing roads need maintenance and rehabilitation; these indeed result in costly investment. From literature, it has been found that for bituminous pavements, polymer can be added in the bituminous mix of the wearing and base courses either as Polymer Modified Bitumen Binder (PMBB) or as Polymer Coated Aggregates (PCA) in order to improve performance of the road and achieve longer life-span. Since only around 4% of plastic wastes in Mauritius are being recycled annually, an investigation on the use of recycled Low Density Poly-Ethylene (LDPE) to pretreat aggregates for use in flexible pavement construction in the form of PCA was carried out. Different percentages of the polymer by weight of the same aggregates were tested for their strength properties using the i) Aggregate Crushing Value (ACV), ii) Aggregate Impact Value (AIV); and the iii) Los Angeles Abrasion (LAA) Test. It was found that the use of recycled LDPE as PCA improved the strength properties of the aggregates, giving higher resistance to loads, impact, and abrasion. As a solid waste management strategy, it was found that by using 2% polymer by weight of aggregates, approximately 7.8 tonnes of LDPE could be used in a road 1km long x 3.75 m x 55 mm thick wearing/base course(s). There would be an insignificant increase in the price of the pavement cost as a proportion of the project cost, due to the aggregate-polymer processing.