By: Keith Browning, P.E.
Keith Browning, P.E., director/county engineer of Douglas County in Lawrence, Kan., watches over about 600 miles of county road. Only 33 miles have an aggregate surface.
The county had plans to stabilize a 1-mile section of gravel road with an aggregate base stabilizer. The job was set for Sept. 12, 2010, but due to some utility issues the project was postponed and the county was unable to stabilize that roadway on the scheduled date.
Browning and his crew were ready and the chemical was present, so they decided to go forward with an alternate project they were considering. The county had a chip-sealed road 1.5 miles long that had developed some soft spots in the base, which caused some potholes and alligator cracks in the wheel tracks.
Douglas County owns a 4-ft-wide Asphalt Zipper machine, which is mounted on the front end of the loader. This machine was capable of pulverizing the 1-in.-thick chip seal and base material. The county decided to repair only the damaged sections of the roadway and incorporate Team Lab Chemical Corp.’s Base One Aggregate Base Stabilizer to add additional strength and performance.
A pressurized water truck, with the base stabilizer and water mix, was attached directly to the Asphalt Zipper machine with a 100-ft 2-in. hose with a ball valve on it to control the volume of liquid.
The chip seal and AB 3 base material was pulverized to a 4.5-in. depth while injecting the stabilizer at the recommended rate. The pulverized material and chemical mix was then removed and placed on the roadway. A Bobcat was used to remove material on the shorter patch areas (100 ft or less) and a motor grader was used on the longer areas.
The material was then placed back in the problem area in two lifts. Each lift was packed with a roller. The patched areas were left unsurfaced for approximately 30 days to allow for the chemical mix to cure. An asphalt-patching machine was used to apply a 1-in. lift of bituminous on the problem areas.
This process was a very economical way to repair the problem areas in this 1.5-mile section.
To date, the road looks great and remains stable.
