By: Roads & Bridges
Interstate-29 runs south from the Canadian border through the Dakotas and Iowa and into Kansas City, Mo. Along the way it connects with important highways like I-94, I-90, I-80 and I-70. The South Dakota DOT (SDDOT) needed to rehabilitate a 15-mile section, and they wanted to see the pavement last a long time. Since the highway’s traffic count and number of trucks had been creeping upward, they planned to use a mix that was highly rut-resistant.
Stone-matrix asphalt (SMA), with its stone-on-stone contact, was the solution. SDDOT officials thoroughly researched SMA before deciding to use it on this important thoroughfare. They designed a mix that included quartzite aggregate and fibers with cellulose and fly ash.
The hot-mix asphalt contractor, Brower Construction, placed a 12.5-mm wearing course on top of the existing pavement, an asphalt overlay over the original concrete. A total of 55,000 tons of SMA was used on the project.
One of the challenges of the job was the quartzite, which is extremely hard. It gives good durability and skid-resistance. The contractor partnered closely with the quarry to make sure the flat and elongated particles in the rock met specifications.
Now, nearly a year after turning loose traffic onto the new pavement on I-29, both Brower and SDDOT are satisfied with the project. “The SMA looks great,” said Joe Feller of SDDOT. “We’ve been very pleased with how it has turned out, and we’re planning to do more projects like it in the future.”
