Iowa WMA Demonstration Highlights National Research

Sep 14, 2011

From the Asphalt Paving Association of Iowa…. A warm mix asphalt (WMA) open house was held on Wednesday, September 8, east of Creston, IA on US Highway 34 to highlight the strong steps that WMA has taken both in Iowa and across the nation.  The demonstration project was part of a national NCHRP 9-49 study being led by Washington State University and Texas Transportation Institute to study the moisture susceptibility and long term performance of WMA.  Norris Asphalt, of Ottumwa, IA is paving the project for IDOT District 4.  The study is comparing both the Evotherm chemical additive and the Sasobit wax additive against a control section of traditional hot-mix asphalt (HMA).  The study will take cores from the project during production, at 100 days and at 300 days to determine if the properties of the WMA change over time. 

“This is a great opportunity to include an Iowa pavement constructed with Iowa materials in a national study.  We hope to learn more about the behavior of WMA as the test sections are evaluated over time.  Nationally, over thirty two million tons of WMA have been placed, with no failures reported.  In Iowa, we have placed over 300,000 tons, with great results.  We will be moving to a permissive specification for next year’s projects, allowing the contractor to choose whether to use WMA or HMA,” said Scott Schram, IDOT Bituminous Engineer.

Brady Meldrem, President of Norris Asphalt saw the advantage of WMA another way, ”Yes, there is a fuel cost savings at the plant; yes, there are some environmental advantages of using WMA, but the deciding factor for us was the better environment for our employees to work in.  The drop in temperature of 50-100°F, no fumes or smell, is better for our employees, and that is what matters to us.” 

Over thirty attendees witnessed the benefits of WMA first hand.  The asphalt was produced at approximately 260°F, a drop of roughly 50 degrees below HMA production temperatures and compacted behind the paver at 245°F.  Previous studies of WMA have found that WMA takes less compaction effort to achieve density of the new pavement.  “We are looking at the use of WMA as a win-win situation for both the IDOT and the contractors,“ continued Scott Schram.  “Equivalent or better quality is being provided by contractors with the added benefits of a friendlier work environment and a reduction of greenhouse gases.  We are able to rely on WMA during cold weather operations as well as provide an added value at a reduced cost to tax payers.”

The Evotherm team was honored to be included in the study and looks forward to contractors in Iowa enjoying the energy savings and environmental benefits of warm mix asphalt.