A stretch of roadway in Milaca laid in October will have to be addressed again in the spring.
County Road 4, which is also 85th Avenue in Milaca, had a roughly 5-mile stretch of asphalt put down, with the northernmost point at 140th Street and the southernmost point at 90th Street.
General contractor W.M.D. Scepaniak, out of Holdingford, worked with paving contractor Knife River Corporation, out of Sauk Rapids, to lay the asphalt in October.
Unfortunately for all parties involved, the asphalt is not up to standard.
Mille Lacs County disapproved of the asphalt quality that was laid.
Though it is still safe to drive on, Mille Lacs County Engineer Bruce Cochran assured, “Some remedial work will have to be done in the spring.”
“We are pursuing corrective action,” Cochran said.
Mille Lacs County is in negotiations with the original contractors to address the entire length of the project in the spring. The contractors have not been paid in full.
Cochran said the reason the work isn’t up to standard is the asphalt is too porous, which is caused by segregation of the hot-mix asphalt.
According to an article appearing in Roads & Bridges Magazine, asphalt segregation can happen at multiple points before the laydown process, from the time the mix is loaded into storage silos at the plant or when it is loaded onto the trucks that haul it to the destination.
Segregation happens when a top-grade aggregate and a low-grade aggregate mix with little to no medium-grade aggregates, where the smaller stones gather together and the larger stones gather together, creating a gap-graded mix.
Often, the source of the issue is when the hot-mix asphalt is stored in the silos or loaded onto trucks, the larger aggregate will fall to the bottom and congregate along the edges of the pile while the pieces of smaller aggregate remain in the center of the pile.
From there, if the hot-mix asphalt has experienced any level of segregation, it will also be transferred to the paver screed as it comes off the dump truck.
Once the segregated asphalt has reached the construction site, there’s not much that can be done to save the altered mix.
With the harsh Minnesota weather conditions, water ponding and freezing become a major issue and Cochran said the road will start to deteriorate from the top down from the weak spots in the asphalt.
Segregation can lead to road failure and a premature breakdown in the road’s aggregate materials, which in turn hampers the road’s life expectancy.
Sometimes, the deterioration isn’t seen for a few years after the asphalt has been laid, but Cochran noted he was made aware of the issue immediately.
Cochran estimated that the current lifespan of the 5-mile stretch in Milaca has been cut short between five and seven years