Full-depth reclamation saves money for Minnesota county

The 12.5-mile County Road No. 30 in Wilkin County, Minn., was in need of repair. This aggregate surface roadway required routine blade maintenance in the 1950s and 1960s, and it received its first bituminous surface in the 1970s.

A 3-in. bituminous overlay was applied in 1987. Since then, the roadway has deteriorated to the point of bad alligator cracking. This roadway had also been cut several times for culvert installations, causing very poor rideability.

“We entertained the option for a 3-in.overlay, but the gravel shoulder width would have been too narrow. We could have removed all the bituminous surfacing and the gravel base, followed by total reconstruction to get the required width, but this would be very time consuming and costly to the county,” said Tom Richels, county engineer. “We decided County Road No. 30 was a good candidate for a full-depth reclamation project with the addition of Team Laboratory Chemical Corporation’s BASE ONE Aggregate Base Stabilizer .”

The county used two reclaimers, a motor grader, a sheep’s foot compactor, four rubber-tired rollers and a water truck. The reclaimers milled up the 5 in. of bituminous surface material and 3 in. of the existing aggregate base.

The aggregate base stabilizer was added to the water truck, and this 8-inch lift was treated with the chemical and water mix and compacted with the sheep’s foot compactor. The top few inches were then bladed and rolled to meet the section required. A motor grader and the rollers took care of final shaping and compaction. The bituminous surface was then added.

“This method was a lot less money to the county than removing the existing surface material and doing a grade widening project. We were able to blade out the reclaimed material to get the needed width, and this method was also much quicker,” Richels said.

Adding the aggregate base stabilizer to the reclaimed material provided additional strength to the compacted base and surface, so the roadway was more capable of handling the paving equipment.

The contractor started reclaiming on May 12. The contractors prepared approximately 2 miles of roadway per day. “The contractors received nearly 100% of the incentives for compaction and ride quality,” Richels said.

Wilkin County ended up with a 24 ft wide bituminous surface roadway with 3 ft wide aggregate shoulders. Falling weight deflectometer testing indicated a 10-ton axle load with a 9-ton load design.