A first in Canada!Alberta Transportation tests an aramid-reinforced asphalt mix to address reflective cracking on Edmonton’s Hwy. 16
In early June 2024, the Alberta Transportation Agency made asphalt pavement history by placing an innovative asphalt mix reinforced with aramid fibers in between the road base and the surface layer of the pavement. The first of its kind reflective crack relief asphalt interlayer (RCRI) was placed just east of Edmonton, Alberta, on a section of Trans-Canadian Highway 16. RCRAI is not new but rather a proven interlayer technology that has been used in the U.S. since 1998 and even earlier in France.
Alberta Transportation decided to test Surface Tech's ARMI interlayer solution, an effective moisture barrier introduced in the U.S. in 2019 that provides five to 10 times greater crack resistance than standard asphalt mixes. It can be hot-mixed and hot-laid, using normal hot mix asphalt equipment, saving time and expense compared to typical third-party fabric interlayer installations.
The test area of Highway 16 is subject to severe thermal cracking caused by extreme low temperatures that penetrated to the base materials. Alberta Transportation worked with Phillip Blankenship of Blankenship Asphalt Tech & Training (BATT) on the interlayer specification and was put to tender in early 2024. Lehrmann was awarded the contract and worked with BATT to optimize the 8.8% PG 64-34 mixture design comprised of a 4.75 nominal maximum size aggregate (NMAS) utilizing balanced mix design (BMD) components specifically tested for the interlayer using Hamburg Wheel Tracking and IDEAL-CT.
BATT has repeatedly found that a thick (25mm) stress-absorbing, fiber-reinforced asphalt interlayer and a complementary, well-designed surface, can combat reflective cracking properly.
“The interlayer can absorb about 80% of the crack movement and relies on the surface to handle the rest based on research studies from the early 2000’s.” said Blankenship. He has worked on the development, testing, and multiple placements of the interlayer since 1998.
On the morning of June 4 all parties assembled, along with Alex Snell from Surface Tech, who worked with Lehrmann to ensure an accurate dosing (131g/tonne) of aramid fiber. Lehrmann placed a test strip of the interlayer followed by the surface layer on the 200 tonne trial section with no problems. During placement, Alberta Transportation sampled the mixture along with BATT for as-built properties. The agency, along with BATT and Surface Tech, will periodically monitor the road section over time and compare it to the performance of the agency’s typical overlay in Edmonton’s harsh, freeze-thaw climate.
Alberta Transportation and Lehrmann Construction Co. deserve special recognition for creating this historic project for Canada. They play a vital role in testing advanced solutions to address a complex pavement problem. Later in 2024, additional sections were placed in Ontario and New Brunswick, continuing the creation of interlayer trials across Canada’s harsh winter climate.
Ready to take on reflective cracking in your asphalt pavements? Contact BATT for more information on ARMI interlayers and for additional asphalt mix design services that can extend the life of your pavements.
