Warm Mix Asphalt and Recycled Asphalt Shingle Demonstration Draws a Crowd

The Asphalt Paving Association of Iowa (APAI) along with Manatts, Inc., Wendling Quarries and the Iowa Dept of Transportation (IDOT) sponsored a demonstration open house on Friday, Oct. 15th, 2010 showcasing the use of Warm Mix Asphalt and Recycled Asphalt Shingles on the Highway 61 project between Muscatine and Blue Grass.

Warm Mix Asphalt (WMA) is the use of chemical additives to asphalt cement or foaming device attachments on asphalt plants that allow the production of traditional Hot Mix Asphalt (HMA) at temperatures 50-100 degrees Fahrenheit below normal HMA production temperatures. WMA was introduced from Europe nearly 10 years ago but has seen a surge in use in the US over the past three years. Warm Mix Asphalt reduces plant fuel costs from 15%-30%, reduces volatile organic compound emissions (already under EPA limits) by 50%-90%, eliminates fumes and smell, improves compactability, dramatically improves asphalt worker conditions and may actually increase the life of asphalt pavements by decreasing the oxidation of asphalt cements during mix production.

The use of recycled asphalt shingles (RAS) is new to the asphalt industry and seems to have an extremely high benefit ratio. RAS has four components beneficial to asphalt mixes: 1. High asphalt binder content, roughly 30% by weight 2. High grade frictional aggregate 3. Fiberglass fibers that promote flexibility in the asphalt mixes and, 4. Lime dust that is a natural anti-strip for asphalt aggregates. The best and greenest aspects of using recycled shingles in asphalt are the savings in landfill waste and the new cottage industry that the recycling has created. Brian Seals, Operations Manager of the Waste Commission of Scott Co., said,” Our shingle recycling program is continuing to gain momentum and we currently have nearly 50 roofing contractors bringing clean loads for recycling; RAS is a win-win for everyone, since 2004 we have diverted 22,000,000 lbs from our landfill.”

The demonstration project was attended by over sixty-five people interested in how the use of WMA and RAS could decrease the amount of virgin asphalt cement needed to make the 1M ESAL asphalt mix. Attendees included contractors, IDOT personnel, county engineers, and a group of engineering students from the University of Iowa. The Hwy 61 project is one of several test projects by the IDOT this year studying the use of RAS, and in this case, the interaction with WMA. Scott Schram, IDOT Bituminous Engineer, says “These two technologies complement one another. Performance testing will help us evaluate the benefits while understanding the limitations of both of these materials. Eventually this project will help us develop permissive specifications.”

The Highway 61 project used three mix designs over the 21,000 ton project: 21% virgin asphalt cement replacement using 20% Recycled Asphalt Pavement (RAP), 5% RAS plus 13 % RAP to equal 30% virgin cement replacement, and the final mix design was 7% RAS with 6% RAP to equal 30% virgin asphalt cement replacement, all the mixes used the Evotherm 3G warm mix additive. Dave Schau, Quality Control Supervisor for Wendling Quarries and mix designer for Manatts, Inc. on the project said, “The mix designing for WMA is the same procedure as HMA except for the temperature, 250 degrees F. The challenge was to figure out how much RAP was needed to be added to the mix to achieve a 30% replacement of virgin binder. “

The demonstration began with a welcome from Tony Manatt, President of Wendling Quarries, followed by Scott Schram describing the project and the WMA / RAS study that was being conducted by the IDOT through a joint Iowa State and University of Iowa research project. Dr. Chris Williams, Associate Professor of Engineering at ISU, spoke about the tremendous advantages of using RAS is asphalt mixes with the “green” advantages and the benefits to the mix itself and Don Moors, of MeadWestvaco, producers of the Evotherm 3G warm-mix additive, followed Dr. Williams, discussing the decrease in greenhouse gas emissions, easier compaction and higher densities on the grade and the decrease in plant fuel by 30% during production. The final speaker was Dave Schau who spoke on the challenges of designing the three mixes and the excitement of watching the hard work come to fruition. “…the WMA is much easier and more pleasant to work with in regards to the temperature and odor. This was a very interesting project with such high quantities of recycled material and I was delighted to have been chosen to do the mix designs.” he said.

Following the lecture, the group went through the Manatts’ plant site and the attendees were able to see and touch the recycled shingles that are ground to the consistency of black sand. The tour continued to the Wendling Quality Control Lab and finally to the project itself. Manatts and Illowa were placing new asphalt shoulders along the existing stretch of Hwy 61. The construction train included a milling operation removing the existing rock shoulders, placement of a four inch asphalt base course and a final two inch surface course, with production averaging three miles per day. The tour finished with a furnished lunch in Blue Grass.

Final thanks to all of our attendees, special thanks to Tony Manatt and Dave Schau of Wendling Quarries, Scott Schram and Jeff Schmitt of the IDOT, Donn Edie and the production and paving crews of Manatts, Randy Soedt and Brian Armstrong of Illowa, Don Moors of MeadWestvaco, Brian Seals of the Waste Commission of Scott Co., Larry Mattusch, Royce Fichtner and Minnie Coree of APAI, Dr. Chris Williams of ISU and Dr. David Lee and his students at the U of Iowa.

Click here to view photos.