LEADCAP - Iowa City, IA

On August 15, 2011, City of Iowa City requested warm mix asphalt to be used on a section of Capitol Street. 350 tons of LEADCAP WMA were used to overlay the street at full-width. The existing pavement was milled and replaced with 1.5-inch HMA binder course and 1.5-inch WMA surface course.  A total of 327 tons of a 1 million ESAL 12.5-mm WMA surface mix with 10% RAP was used. The asphalt mixture was stored in a holding container until it was ready to be loaded onto dump trucks at 265°F. It was then driven to the jobsite and placed on top of the binder course at 240°F. The WMA mixture was compacted at a temperature of 230°F. On September 27, 2012, due to the underground utility rehabilitation, a part of the Capitol Street was reconstructed using the 100 tons of the same LEADCAP WMA mixtures.Temperature for both production and compaction was 45°F lower than HMA. LEADCAP additive was used for this mixture at a rate of 1.5% of the total binder content. Traffic was allowed on the new mat as soon as each side was compacted. Field implementation results are summarized in the table below.