A Time to Mill and a Time to Scrub
While a mill and fill application can produce satisfactory results, it was not the most economical solution for this particular project. By applying a scrub seal on SR 82, leveling the roadway and adding a HMA surface (as opposed to milling out four inches of bad mix and replacing 440 pounds per square yard of plant mix), GDOT would save approximately $200,000.
One Clean Sweep
Ergon A&E’s eScrub is a rejuvenating emulsion that not only seals mass cracks, but also, due to its high levels of polymer modification, restores quality and durability to the road. In the scrub seal process, emulsion is sprayed onto the distressed road surface via distributor truck with a mechanized scrub broom attached to ensure emulsion is forced into the cracks. Aggregate is then spread over the road and compacted using pneumatic tired rollers. GDOT agreed to try scrub sealing the distressed section of SR 82 with eScrub to see if it would in fact be the solution to fix their cracked up situation.
Taking Care of Business
eScrub was applied at a shot rate of approximately 0.35 gallons per square yard followed by the spreading of #7 aggregate (or stone) at 20 pounds per square yard. GDOT leveled the scrub-sealed course with 9.5 mm HMA applied at 75 pounds per square yard, approximately ½ inch. This was nearly a two-week process. A few months later, as scheduled, the leveling course was topped with an inch of 12.5 mm HMA for the final riding course.
Eleven months after application, with the treated section of SR 82 safely guarded with a polymer modified, rejuvenating scrub seal and topped with up to 1½ inches of HMA, there are no signs of cracking. GDOT has plans to duplicate this treatment on over 50 centerline miles of state roadways, continuing to employ a versatile treatment while deferring the costs of more intrusive measures.
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