Environmental analysis of asphalt pavement maintenance using modified binders in developing countries: case study in Bogotá, Colombia

This study presents an environmental analysis of four maintenance alternatives for a case study to be conducted in Bogotá, Colombia. The study involves a conventional hot-mix asphalt (CHMA), a polymer-modified hot mix with styrene butadiene styrene (PM-SBS) and two crumb rubber asphalt mixes, asphalt rubber dense-graded (AR-DG), and asphalt rubber gap-graded (AR-GG). This paper presents an analyzes of the environmental impacts of these maintenance options by using the Eco-indicator99 as a life-cycle inventory -tool (LCIT). The analysis is complemented by estimations of the global-warming potential (GWP) index and energy consumption of each option. Two scenarios and their environmental impacts were considered: using 1) heating oil (HO) or 2) natural gas (NG) as fuel for drying and mixing in an asphalt plant. Also, the binder transportation was analyzed with the consideration that, in Colombia, there are only two national refineries with binder production to cover the country demand. The impacts of a polymer-modified plant (PMP) and the tire-shredding process were considered as well. The results showed that the production of materials contributed roughly 55% to 65% of environmental load (EL), and heating aggregates contributed almost 29% of EL. Maintenance conducted using AR-GG was considered the more eco-efficient option with the lowest EL, on the other hand AR-DG, and PM-SBS showed to have similar EL.