The Nicollet County (Minn.) Highway Department needed to repair transverse cracks on County Road 13. This two-lane road has annual traffic of approximately 300,000 vehicles, including large tractor-trailers. In addition to traffic, the fluctuating Minnesota weather plays a factor in creating pavement distresses. Nicollet County has temperatures that range from an average high of 84.3°F to an average low of 3.5°F. The area also receives an average of 30.14 in. of precipitation per year, including snow and freezing rain.
In the past, Nicollet County had been treating depressed, transverse, and longitudinal cracks by spraying a tack coat, installing a fine hot mix and compacting. Its normal crew size is approximately eight to 10 people. Its production yield typically was approximately 1 mile per day, full road width. This method is very labor-intensive and time-consuming. The performance duration of the hot mix is sometimes only one year. No other methods or products have been explored—until recently.
On a partly sunny, 60° day, a five-member crew applied Mastic One—a versatile hot-applied, pourable, aggregate-filled, polymer-modified asphalt repair mastic from Crafco Inc.—to a single lane at a time utilizing a mobile operation. There was no prep work performed prior to installation. The Patcher II—a Crafco melter/applicator—was driven down the center of the lane. The Mastic One, which contains selected aggregate to ensure strong load-bearing and skid-resistant characteristics, was placed by first pulling the full drag box from the center of the lane inward to the centerline, returning to the Patcher II for refilling, and then finishing the crack by pulling outward to the fog line.
The County crew quickly realized how much more productive the process was and that it utilizes less manpower and equipment. These benefits, along with increased pavement smoothness and ride quality, essentially sold the product and won the confidence of the Nicollet County Highway Department.