But how do you determine whether infrared is a viable option? Kieswetter says make sure the pavement surface is relatively flat.
"As long as there's not a significant change in grade elevation we try to repair with infrared first to reseal the surface. It's a cheaper way to maintain it," Kieswetter says. "As soon as you get the surface rolling up and down where you can see the subgrade has been affected by water then you probably want to try a different approach. But as long as the pavement is not severely changed in grade we'd try to reheat it and repair the surface with infrared."
Kieswetter says a number of industrial and commercial clients are requesting an infrared repair be tried first because it's a better maintenance process, it's quicker, and less costly than a remove-and-replace effort.
"In the correct circumstances infrared repair is a great option for pothole patching," Groh says. "It's one of the best applications for infrared technology."
"Remove and replace" improves pavement
Sometimes the tried-and-true remove-and-replace approach is still the best option. While more time consuming, more labor and equipment intensive, and more expensive, this approach will yield some of the best results and actually improve the overall quality of the overall pavement.
The following steps will result in a successful pavement restoration repair.
- First, because the remove-and-replace approach involves a crew and takes longer, it's important to set up traffic control around the worksite. Contractors working on-road can consult the American Traffic Safety Services Association for appropriate traffic control setups. Contractors working on parking lots and low-volume streets can establish their own traffic control by paying close attention to traffic flow and pedestrian traffic and redirecting people and vehicles away from the worksite. Workers also should wear appropriate high-visibility clothing.
- Mark out the area to be removed, either with spray paint or chalk. Marked out edges should be straight sided and most research indicates a rectangular or polygon shape works best.
"It's important to exceed the limit of damage so the cuts and repairs extend go into stable pavement," Groh says. "One of the most common causes of failure of a restoration repair is not extending the cut into pavement that is stable. When you cut out too small an area you are leaving damaged pavement to surround your patch, and that damage will work its way into the repair you've just made."
- Remove the existing damaged pavement. Groh recommends milling, sawcutting, or using an air hammer (in that order) as ways to remove the pavement and create clean edges. Using an air hammer is the least preferable option because the action of the hammer itself can create cracks in what had been stable pavement.
- Excavate to a stable grade, making sure to remove all damaged or wet material of the base and subbase. "A lot of restoration patches fail because not a lot of attention is paid to the subbase material," Groh says. "It's essential that any wet or otherwise damaged material be removed from the hole before going on."
- Replace base aggregate as necessary.
- Tack vertical edges of the repair to improve adhesion.
- Install asphalt in two lifts. Groh recommends no less than 4 inches total of hot mix asphalt.
"Two lifts is essential because sometimes you think you are working in a stable area but after you place the mix and begin compacting it settles and you realize the area was not as stable as you thought," Groh says.
In those cases you are left with a very thin lift to place on top just to level the pavement surface or you are creating a depression if you don't add mix. To avoid the problem place a first lift and then compact that.