A typical day in California includes sunshine and blue skies, unless you are near the Golden Gate.  The iconic bridge that connects San Francisco to Marin served as the backdrop for a paving project that utilizes the latest asphalt innovation, Evotherm®, the premier warm mix asphalt (WMA) technology.  Ghilotti Brothers Inc., Dutra Materials, and Telfer Oil Company proposed the use of Evotherm WMA to the Central Federal Lands Highway Division (CFLHD) of the Federal Highway Administration (FHWA) for use on a Golden Gate National Recreation Area paving project.  The project included the reconstruction of East Road with 4 inches of hot mix asphalt (HMA) over aggregate base.  The Contractor utilized Evotherm to achieve the required in-place density during the cool paving temperatures of summer.  

Ghilotti Brothers paved East Road on August 10th and 11th in cool conditions.  As anticipated, the ambient conditions were not ideal for HMA paving.  The high temperatures ranged from 58°F-62°F and were accompanied by fog, drizzle, and wind.  As a result of the cool ambient conditions, the breakdown rolling operations started after the pavement surface temperature dropped below 210°F.  The Evotherm improved the workability of the mix at the lower temperatures which resulted in core densities between 92% and 95% (minimum required was 91%).  

The CFLHD had not constructed a WMA pavement prior to this project.  They were concerned with rutting and moisture sensitivity of the HMA.  Telfer Oil provided several research reports and project information from Caltrans projects that addressed their concerns.  Research included data from the first two phases of the WMA Heavy Vehicle Simulator (HVS) by the University of California Pavement Research Center (UCPRC).  The UCPRC concluded that the WMA pavement performed similar to or better than the conventional HMA pavement.  Telfer also provided information from Caltrans projects that included work on I5 in Orland, CA1 in Point Arena, and US101 in Scotia.  

The ability to achieve density in less than ideal conditions demonstrated an important benefit of Evotherm in asphalt mixes.  Evotherm mixes can also be produced at significantly lower temperatures that will result in a reduction in energy, emissions, and odors associated with asphalt mix production.  Please contact Telfer Oil for more information.