Potential Use of LDPE and Crumb Rubber Waste in Asphalt Binders

Recently, great attention has been given to the environmental impact of greenhouse gas emissions as well as the impact of non-biodegradable waste materials on the environment. Asphalt road production is a huge source of carbon dioxide emission both during the production of asphalt cement and the paving process. The rapid growth of the automobile industry and the worldwide dependence on vehicles have led to a massive increase in rubber tire waste. On another hand, Low-Density Polyethylene (LDPE) such as plastic bags and food packaging plastic containers are a major source of non-biodegradable waste. This research studies the incorporation of these waste materials into the asphalt binder without compromising its function. Replacing a portion of the asphalt binder may help reduce carbon dioxide emissions during the production process. Additionally, incorporating waste material into the asphalt mix minimizes the amount of waste material reaching landfills. The aim of this research is to incorporate waste materials, sourced in Egypt, into asphalt binder to improve road quality. The research compares non-modified asphalt binders, crumb rubber-modified asphalt binders and LDPE-modified asphalt binders using the Superpave technique. Waste tire rubber and second-grade LDPE plastic bags were processed into powder and incorporated into asphalt binder separately at varying percentages using the wet method. It was found that both modifiers led to significantly better performance grades of the asphalt binders. A combination of rubber and LDPE modified asphalt was also examined with respective percentages of each modifier selected according to their individual performance. The 5% LDPE modified binder was found to be the best performing asphalt binder when compared to the rest of the modified binders. The 5% LDPE and 7% CR modified asphalt were found to have PG of 76–28 and PG 70–28, respectively. The improved performance of the modified asphalt binder was evaluated against the required PG of Egyptian roads and it was found that adding 5% of either CR or LDPE will substantially enhance the virgin Egyptian asphalt binder to the point of meeting the regional Egyptian asphalt requirements of PG 70–10 and PG 76–10, respectively.