O’Brien County Open House is a Hot Ticket

On a cold and blustery day in NW Iowa, nearly fifty county, city and consulting engineers came to see the hottest ticket in Portland concrete cement (PCC) road rehabilitation, the asphalt interlayer. An Open House hosted by O’Brien County, Tri-State Paving and the Asphalt Paving Association of Iowa (APAI) was held on Friday, October 10 on county Road B-14, approximately five miles north of Sheldon, IA. “I’m excited by the amount of interest in the asphalt interlayer,” said Jeremy Anderson, General Manager of Tri-State Paving. “This is our first time designing and placing this material, none the less, the mix design process went smoothly, the asphalt looks great and the paving operation is the same as traditional hot-mix asphalt (HMA), except that you only static roll the mat.”

The asphalt interlayer is a one-inch, polymerized hot-mix asphalt with target voids between 0% - 2%. Typical asphalt cement content ranges from 8% - 10%. The asphalt interlayer is overlaid with 3”-4” of traditional HMA. The result is longer-lasting rehabilitations of failing PCC pavements. The Iowa DOT has a Developmental Specification (DS-12054) in place for agencies interested in using this unique material. The asphalt interlayer provides an impermeable, highly-flexible membrane over the existing PCC roadway to help retard the reflective cracking through the HMA overlay.

“We are thrilled with the initial appearance and ride of the asphalt interlayer,” said Tom Snyder, O’Brien County Engineer. “B-14 is a 1970’s PCC road that we have patched extensively and was by far the worst road in the county. We believe the asphalt interlayer will give this road long-lasting performance, and with the additional three inches of HMA we should have an extremely smooth ride. This is going to make the residents along B-14 very happy.”

The use of the asphalt interlayer continues to proliferate through city, county and IDOT projects (see APAI story Build It and They will Come”). “It works,” said Scott Schram, IDOT Bituminous Engineer. “The one-mile test section we placed on I-35 north of Mason City last year developed 65 reflective cracks in the non-interlayer lane and 16 cracks in the asphalt interlayer lane. We are going to continue to monitor this section, but initial results are extremely positive.”

Tri-State paving was able to place the 5200 tons of asphalt interlayer over the seven mile stretch in just two days. “At one inch thick, it goes down fast,” said Anderson, “you are almost at a brisk walk next to the paver. With another two lifts of HMA, this road could be an APAI Smoothness Award winner.”

Specials thanks to all of our attendees, to Tom Snyder and the O’Brien Co. Engineering Staff and Board of Supervisors; Jeremy Anderson, Brian Heger and the Tri-State paving crew and Doug Schrader and his Staff at Ziegler NW for the coffee, tour and hat!

If you are interested in more information on the asphalt interlayer, or other cost-saving rehabilitation methods, contact the APAI at 515-233-0015 or [email protected]

Click here to see the O'Brien County Open House Slide Show.

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