"Once they saw how well it worked both organizations embraced it," Knipfing says.
It's easy to see why. Where traditional repair methods always leave cold seams that can allow water to penetrate into the base and subbase, the infrared process essentially results in a seamless pavement repair.
"Infrared repair is the only method currently available that will return the road to its 'as before' condition,"Knipfing says. "Once it's installed properly, it's an integral part of the pavement and fused together with the surrounding pavement."
Knipfing estimates that his four crews have repaired some 20,000 utility openings-including one 1.8-mile long trench-in the eight years his contracting company has been using infrared process. And he says there is no trick to using the infrared process to repair utility cuts.
"It's the typical infrared operation and process—only the application is different," he says.
Once the utility has completed its work, it replaces and properly compacts the fill material. It then places stabilized 3/4-inch base asphalt to grade, and properly compacts it. After 90 days Knipfing Asphalt Solutions goes to the jobsite and conducts the final step in the process.
The crew uses the infrared equipment to heat up both the repair and the surrounding pavement and then removes a percentage of the 3/4-inch base asphalt. They replace what they take out with 3/8 inch wear course asphalt, rake and lute it to grade, then compact the patch, working from the outside edges in toward the center.
"It's important that once the fill and base material is put in place that it is left untouched for 90 days. This allows adequate time for both materials to fully settle and compact," Knipfing says. "The amount of settlement varies. Sometimes it's none and sometimes it's as much as almost two inches. It all depends on how well the compaction was done on both the fill and the asphalt base."
He says that if the final infrared repair is done the same day the utility's work is completed, further settlement will most likely occur, creating a depression in the pavement.
"As the asphalt settles it causes the repair to separate from the surrounding road, enabling water to enter and almost guaranteeing the patch will fail,"Knipfing says. "By waiting 90 days you are virtually eliminating that problem. The 90-day period is key."
Knipfing says the size of the patch determines the amount of hot mix asphalt he has to add during the final repair. A patch can require as little as two shovels full or as much as wheelbarrow full.
"It just depends on the compaction, the settling and the size of the patch," he says.
He says current infrared equipment is ideal for this type of pavement work because most units can be configured in a variety of ways, enabling the contractor to select the configuration that best fits the size of the patch.
"It creates a sound repair far better than any other conventional method," he says.
Knipfing says it's difficult to quantify the costs or even cost savings when comparing infrared repair to standard utility cut repairs because there are so many variables, including size of the repair, to consider. He says the up-front cost of the process is typically more expensive than conventional means," but when you factor in the reduced call-backs it's essentially a wash.
"A significant benefit to the utility company is that the municipality that owns the street is thrilled to have it returned to 'as before' condition. This removes one of the largest headaches faced by underground utility companies 'keeping the municipality happy.'"
Knipfing says the infrared process is equally effective on utility cuts that were previously repaired by conventional methods and have subsequently failed. In the past, failed utility cuts were repaired with skin patches, which didn't last long, or by removing the entire patch and replacing it the same way it was done initially.
"But you can use the infrared process to repair these failed utility cuts. It's kind of like repairing a pothole using infrared," he says. "You follow the same approach."