Environmental Benefits of In-Situ Recycling of Pavements

Cold in-place recycling (CIR) is an innovative pavement rehabilitation method that typically processes up to 125 mm of an existing hot mix asphalt (HMA) pavement, sizes it, mixes in additional asphalt cement, and lays it back down without off-site hauling and processing. A recent development in CIR technology is the use of expanded (foamed) asphalt, rather than emulsified asphalt to bind the mix. In this new process, hot asphalt cement is pumped through an expansion chamber on the cold recycling unit, where a small amount (1%) of cold water is injected and immediately vaporizes. This creates thousands of tiny bubbles within the hot asphalt cement causing it to rapidly expand. The expanded asphalt is then mixed with the reclaimed asphalt pavement. This combination of CIR and expanded asphalt technologies is termed Cold In-Place Recycled Expanded Asphalt Mix (CIREAM). The Ministry of Transportation has an active CIR and CIREAM program that is strongly promoted and monitored. This submission outlines the impact CIR/CIREAM has had on the environment compared to a traditional mill and overlay treatment, its cost effectiveness and how the MTO promotes and monitors this technology. This project was nominated for the 2006 TAC Environmental Achievement Award.