The Kosciusko (Indiana) County Highway Department undertakes improvement projects on 50 to 100 miles of roadway annually and, like many counties across the U.S., faces constant pressure to contain costs in the face of decreasing budgets. Although resources are limited, county residents and businesses still have high expectations for road quality and timely attention to seasonal maintenance and necessary repairs.
In 2012, county road officials concluded that implementation of more effective methods of stabilizing base gravel in problem roads would satisfy budgetary constraints while meeting the road quality expectations of taxpayers. Maintenance and repair costs would be reduced and taxpayer satisfaction would improve by making the roads more durable and reducing the frequency of disruptive repair and maintenance operations, according to county officials.
Earlier road base stabilization projects in Kosciusko County relied on compaction and weathering effects to stabilize road bases. Specialty stabilizer materials incorporated into the road base gravel during some projects did not significantly improve results. County officials were especially unhappy with the length of time required to stabilize road bases, the poor durability of the roads and the inconvenience road deterioration and subsequent repair and maintenance requirements imposed on motorists and local residents.
To identify a better solution, Kosciusko County road personnel talked to officials from neighboring counties who face similar challenges with sub soils, gravel and climate conditions. They also discussed their concerns with Great Lakes Chloride Sales, Inc., Kosciusko County’s source for calcium chloride used for road dust control.
County officials gathered input from neighboring counties that had used Liquidow liquid calcium chloride, produced by Occidental Chemical Corporation (OxyChem) and provided by Great Lakes Chloride. This encouraged Kosciusko County officials to implement a pilot test on a one-mile section of gravel road that was prone to deterioration and required frequent blading and other repairs.
“We’ve been using liquid calcium chloride for dust control for a long time, but this was the first time we used it for road base stabilization,” said Scott Tilden, Kosciusko County Highway Department Superintendent.
The section of County Road 600 East involved in the pilot project was plagued by potholes and washboarding, which made driving uncomfortable and had the potential to damage or accelerate wear on vehicles. Constant deterioration also kept county crews busy making spot repairs and performing maintenance blading, consuming man and equipment hours as well as budget dollars.
The stabilization process began with the addition of three inches of new aggregate to the road surface. The mixture of fine and coarse material was bladed into the existing road base to remove washboards and potholes. The road was then shaped to a 3.5% crown. The new surface and six inches of the underlying road base were ground to loosen and mix the material and allow uniform penetration of liquid calcium chloride.
Following behind the grinder was an application truck from Great Lakes Chloride, which injected three quarters of a gallon of a 38-percent concentration of the product per square yard of road surface. A 12-ton vibratory pad roller following the tank truck compacted the rehabilitated road base in a single pass, completing the stabilization operation.
The road was then bladed again and reshaped to a 2.5-percent crown to prepare it for a hard surface finish. A final treatment was applied at a quarter gallon per square yard to limit any residual dust issues and help further stabilize the road base.
Six weeks after stabilization, road crews returned to County Road 600 East and applied two chip and seal treatments, creating a two-inch thick hard road surface that completed the project.
As a result of the project, Kosciusko County plans to expand its use of liquid calcium chloride to stabilize other roads.
“We expect that, by using the liquid form of calcium chloride as part of an improved stabilization process, the need for periodic surface blading and gravel replacement will be significantly reduced,” Scott Tilden, Kosciusko County Highway Department Superintendent, said. “That will help conserve budget dollars and reduce traffic disruption on our county’s 120 miles of gravel roadway.”