Becca Lane

Sustainable Pavements: Environmental, Economic, and Social Benefits of In Situ Pavement Recycling

The Ministry of Transportation Ontario, Canada, is committed to using technologies to help build a more sustainable transportation system that supports todays needs while protecting the environment for future generations. Cold in-place recycling (CIR) is an established pavement rehabilitation technology that processes an existing asphalt pavement, sizes it, mixes in additional asphalt cement, and lays it back down without off-site hauling and processing. The added asphalt cement is typically emulsified asphalt. A recent development in CIR technology is the use of expanded (foamed) asphalt, rather than emulsified asphalt, to bind the mix. This combination of CIR and expanded asphalt technologies is termed cold in-place recycled expanded asphalt mix (CIREAM). Both CIR and CIREAM technologies support the philosophy of a sustainable transportation system. More specifically, CIR and CIREAM meet the criteria for a sustainable pavement: safe, efficient, economic, environmentally friendly pavement that meets the needs of present-day users without compromising those of future generations.

Pavement Preservation: A Solution for Sustainability

The Ministry of Transportation of Ontario, Canada (MTO), is dedicated to maintaining quality roadways in a sustainable manner. In recent years, MTO has implemented pavement preservation strategies to maximize cost savings in repair operations and to maintain pavement condition. Pavement preservation treatments are considered sustainable because they improve pavement quality and durability and extend pavement service life, while reducing energy consumption and greenhouse gas (GHG) emissions. Pavement preservation is a proactive, planned strategy that extends the life of the pavement and provides a cost-effective solution for pavement management. This paper outlines the various pavement preservation treatments used by MTO to achieve sustainability. These preservation treatments include crack sealing, slurry seal, microsurfacing, chip seal, ultrathin bonded friction course, fiber-modified chip seal, hot-mix patching, and hot in-place recycling. With use of the PaLATE software, pavement sustainability is quantified by comparing the energy consumption and GHG emissions generated for various pavement preservation strategies against typical rehabilitation and reconstruction treatments. This paper presents the benefits of pavement preservation by considering the service life of each treatment and calculating the associated energy consumption and GHG emissions per service year. Results indicate that pavement preservation strategies provide a significant reduction in energy use and GHG emissions when compared with traditional rehabilitation and reconstruction treatments. Although pavement preservation has been proved to be a cost-effective solution, there are numerous challenges and barriers to overcome. Some of the challenges and solutions as well as the strategies to promote pavement preservation for sustainability are presented in the paper.

Implementation of Cold In-Place Recycling with Expanded Asphalt Technology in Canada

Cold in-place recycling (CIR) is a pavement rehabilitation method that processes an existing hot-mix pavement, sizes it, mixes in additional asphalt cement, and lays it back down without off-site hauling and processing. The added asphalt cement is typically emulsified asphalt. A recent development in CIR technology is the use of expanded (foamed) asphalt rather than emulsified asphalt to bind the mix. This combination of CIR and expanded asphalt technologies is termed cold in-place recycled expanded asphalt mix (CIREAM). The Ministry of Transportation Ontario (MTO) constructed a CIREAM trial section on Highway 7 in July 2003. The 5-km CIREAM trial section was constructed adjacent to an 8-km section on which conventional CIR was performed. CIREAM placement resulted in a smooth, hard, uniform surface that provided an excellent platform for paving operations. The CIREAM placement progressed in a continuous and efficient manner, with 5 km placed over a 3-day period. Indirect tensile strength testing was carri...

Ten-Year Performance of Full-Depth Reclamation with Expanded Asphalt Stabilization on Trans-Canada Highway, Ontario, Canada

In 2001, the Ministry of Transportation Ontario, Canada, constructed its first stabilization project involving full-depth reclamation with expanded (foamed) asphalt on the Trans-Canada Highway, south of Wawa, Ontario. The project involved three mix designs, two with corrective aggregate and one without corrective aggregate. A control section of full-depth reclamation with the same thickness of hot-mix overlay (without expanded asphalt stabilization) was placed in the middle of the project. The project has been monitored annually for the past 10 years. Analysis of roughness data and pavement distress data indicated a significant difference between the test sections with expanded asphalt stabilized base and the control section. The expanded asphalt stabilization has delivered superior performance compared with the conventional full-depth reclamation with hot-mix overlay. Performance curves for the treatments on this project were compared with the ministrys average performance curve for full-depth reclamation (reconstruction) projects and with the performance of treatments on two adjacent projects. This project demonstrated the exceptional performance of the expanded asphalt mixes through 10 years of proven superior pavement condition and ride.