Pavement Scientific International: Recycling Asphalt Concrete for Road Construction

Pavement Scientific International (PSI) is on the cutting-edge of sustainable infrastructure technology. The company is currently developing a project that benefits both the environment and citizens by using recycled asphalt concrete in road rehabilitation.

“Recycled asphalt concrete is used to rejuvenate urban streets and highways that have surpassed their design lives and, as a result, are failing structurally,” says PSI President Curtis Berthelot. He explains that PSI reconstructs damaged roads with “cold in-place” technology. By grinding down to a depth of up to 400 mm, the technology, which uses little heat, recycles the asphalt in its existing location. “Stabilizers are added to the asphalt concrete and a thin layer of asphalt is placed on top,” says Berthelot. “The technology essentially makes the old road into a new road.”

Cold in-place technology is beneficial for both the environment and for area residents. PSI has recently completed a study that reports the technology saves 50 to 70 per cent in emissions. Also, since the technology recycles the existing asphalt concrete, old materials do not need to be discarded. Therefore, heavy loads of old materials are not traveling on other roads in the area. “Cold in-place technology eliminates the damage caused to neighbouring roads that results from conventional road construction methods,” says Berthelot.

Furthermore, the technology developed by PSI conserves aggregates, an important natural resource. Gravel is a non-renewable resource required for a variety of infrastructure and, moreover, for city growth. Cold in-place road construction helps to preserve vital aggregate resources, since it does not use gravel in the rehabilitation process.

The technology also benefits citizens who utilize the roads that are being reconstructed. “There is minimal interruption to local traffic,” explains Berthelot. “With cold in-place technology, the road is still in service, even as the reconstruction is taking place.”

Berthelot says that PSI began designing cold in-place technology 10 years ago. Initially, the designing process involved developing new engineering protocols. Although protocols existed for conventional road construction, new systems were required to apply the new cold in-place technology.

In the summer of 2006, PSI joined with the City of Regina to test and further develop the technology. Harlan Ritchie, Director of Roads and Traffic Engineering with the City of Regina, sees great benefits from the technology. “Over the long-term, the cold in-place technology will result in lower costs. It will have a reduced environmental impact as well as reduced impact on residents and streets adjacent to the projects,” says Ritchie.

PSI has partnered with Communities of Tomorrow (CT) on this and other road construction technologies it is developing. “CT has funded PSI seed projects for engineering system development,” says Berthelot. He adds that CT also assists PSI with research by providing much-needed resources. “PSI is looking forward to working with CT as it brings its cold in-place technology closer to the stage of commercialization,” Berthelot says.