Last Updated on Thursday, 02 September 2010 07:56 Written by Brandon Milar Thursday, 02 September 2010 07:46

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.

Last Updated on Sunday, 18 July 2010 10:02 Wednesday, 07 July 2010 10:57

Bonded Wearing Course:  Serving Sacramento for 7 years

As new technologies are introduced to Contractors and Agencies, the Engineers always say, “I need to see it perform”.  In 2003, the first Bonded Wearing Course (BWC) was constructed by Windsor Fuel Company (WFC) for the City of Sacramento.  The City identified three locations that would be suitable for the BWC treatment.  The locations included Front Street from north of N Street to Ramp Way, 24th Avenue from Broadway to Donner Way, and V Street from Stockton Boulevard to 57th Street.  These streets have various types of traffic which include truck traffic to fuel storage terminals on Front Street, residential traffic along a collector, and traffic associated with a hospital on V Street.  The City utilized the BWC as a way to address immediate pavement distresses until a more permanent solution could be constructed.   The distresses were significant on all three streets and included moderate to high severity fatigue cracking, high deflections based on falling weight deflectometer testing, and failed trench patching.   Except for a section of Front Street (V Street to Ramp Way), the City did not treat the existing cracks.

                            BEFORE (MAY 2003)                                                            AFTER (DEC 2009)                                    

WFC utilized an integrated spray paver to construct the BWC.  The paver applied a special polymer modified tack coat (0.2 gal/yd2) and applied the polymer modified gap-graded HMA mix over the tack coat.  This single pass operation was followed by two steel wheeled rollers that compacted the mix.  Mix was placed and compacted to a thickness of ¾”. 
In April of 2010, the City reviewed the current Pavement Quality Indices and these sections ranged from the low 70’s to the low 90’s.  Mr. Dmytrow, Mr. Milar, and Mr. Lara from Telfer oil Company conducted a review of these streets in June of 2010.  They reported back that the roadways were in good condition.  On Front Street, areas with high severity fatigue cracking, near O Street, exhibited good surface texture with low to moderate reflective cracking.  Both 24th and V Street were in good condition with minimal reflective cracking.
In general, the BWC has exceeded the City’s expectations for longevity.  The polymer modified asphalt binder and tack coat assists in mitigating reflective cracking while the gap graded HMA provide a durable surface for various amounts of traffic conditions.   While Engineers ask the question does a BWC perform in the urban environment, the answer is a resounding YES!