Carbon footprint of asphalt road pavements using warm mix asphalt with recycled concrete aggregates: A Colombian case study

The construction of road pavements is an important consumer of natural resources and a major contributor to the human-driven emission of greenhouse gases (GHGs). As increasing attention has been paid to sustainability and natural resources preservation, highway agencies are looking for alternative materials and innovative asphalt mix technologies to reduce the carbon footprint of their pavement construction practices. In this study, a comparative carbon footprint assessment was conducted to evaluate the potential environmental benefits related to the use of recycled concrete aggregates (RCA) as a partial replacement of coarse natural aggregates in the production of Warm Mix Asphalt (WMA). In order to estimate the GHGs emissions associated with the use of these alternative resources in the construction of road pavements in Barranquilla, Colombia, primary data was gathered from companies in the region. The SimaPro software version 8.4.0 was used for modelling the processes analyzed in the case study according to the methodologies proposed in the ISO 14067 standards “Greenhouse gases- Carbon footprint of products- Requirements and guidelines for quantification and communication” and ISO 14040 standards “Environment management- Life cycle assessment- Principles and framework”. The pavement life cycle phases and processes included within the system boundaries were the following: (1) materials production and transportation to the mixing plant; (2) materials processing and mixtures production at the mixing plant; (3) mixtures transportation to the construction site; and (4) pavement construction. Finally, three percentages of RCA replacements were considered in the production of WMA.