With a little help, longer than you think. We just took a look back at a road that was chip sealed nine years ago and it looks great!
Okay, let’s come clean a little. First, it was a double shot of chip seal and second, it was assisted with a geotextile fabric layer. But still, this old concrete road was showing a lot of wear and with some extra care, it is well on its way to a record service life.
In June 2012, Cecil County (Maryland) Roads Division treated Basil Avenue with some patching, followed by geotextile and a double shot of chip seal as a pavement preservation method to extend the roadway’s useful life. We filmed the operation at that time and it has gotten a lot of airplay on three different YouTube channels, including our Delaware T2/LTAP Center channel.
Basil Avenue (18-20′ width) was an existing concrete roadway with approximately 2″ asphalt overlay. The surface exhibited oxidation and some cracking in 2012. Cecil County performed some sealing of the distressed/cracked asphalt with an AMZ machine, but the surface was not crack sealed. Most of the reflective cracking due to transverse joints were not sealed. Some asphalt patching (~2″ thick) of the existing surface and some thin lift repairs (~1″ thick) preceded the chip seal and fabric treatment. Our video shows the June 27, 2012 application of PG-64 binder and Mirafi MPV 500 polypropylene non-woven fabric followed by two layers (“shots”) of chip seal, using 0.4 gal/SY CRS-2 emulsion (second layer used 0.37 gal/SY) and #8 stone at 17 #/SY (both layers).
Optimal performance expectations for chip seal are 7-10 years (https://roadresource.org/), whereas average performance is typically 3-5 years. The goal with this modification was to hedge against time and produce a wearing surface that would perform well. It would appear that the treatment to Basil Avenue is on a trajectory to enjoy a much more extended service life than had chip seal alone been applied.
Nine years later, the surface exhibits only minor cracks, with no apparent reflective cracking to date. The underlying concrete road normally would send reminders to the surface within a few years in the way of reflective cracks. But in Basil Avenue, this has not happened thus far and the roadway has captured our attention as a case study. It is likely that we’ll be making our way back every year or two to check in on the wearing course. It certainly looks like it will outperform, so now it is becoming more of a question of by how much. It’s nearby for us, so look for us to check back on it in a couple years.
The Delaware T2/LTAP Center’s Municipal Engineering Circuit Rider is intended to provide technical assistance and training to local agencies and so if you have pavement management questions or other transportation issues, contact Matt Carter at matheu@udel.edu or (302) 831-7236.
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