Integrated Mechanistic-Based Framework for Sustainable “Green Street” Rehabilitation of Urban Low-Volume Roads

Abstract

This research developed a mechanistic-based framework for recycling rubble materials into high-value-added engineered road structural materials for use in urban road rehabilitation. Scientific-based engineering methods were integrated with advanced materials processing, road construction, and nondestructive asset management techniques to explicitly quantify the benefits of recycled material systems using reclaimed asphalt pavement (RAP) and portland cement concrete (PCC) rubble generated within the city of Saskatoon, Saskatchewan, Canada. The ability to process RAP and PCC rubble to meet or exceed conventional granular aggregate specifications with minimal waste was demonstrated. It was found that RAP and PCC aggregates can exceed the mechanistic material constitutive properties of conventional city of Saskatoon granular base aggregates by at least 30%. The mechanistic material property value of unstabilized RAP and PCC was demonstrated in addition to the benefits of various cold stabilization systems using cement and emulsion. Recycled RAP was used as a black base layer and PCC was used as a subbase course or a drainage and stress-dissipation layer, or both, in rehabilitated road structures of nine “Green Street” test sections constructed in Saskatoon. These test sections met or exceeded target structural designs and were validated by using nondestructive heavy-weight deflectometer testing. The use of recycled RAP and PCC rubble materials for urban road rehabilitation had economic, social, environmental, and energy benefits for the city of Saskatoon. Recycled rubble materials were found to provide a technically viable and cost-effective solution for rehabilitating urban low-volume roads relative to conventional granular aggregates.