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!