Avoid common problems, patiently follow the process
By Krystal Strassman
It happens to the best asphalt paved surface…. the dreaded pothole. Potholes are depressions in a paved surface that can vary in size and shape. They are caused by the expansion and contraction of water that gets into the ground under the pavement. When water freezes, it expands.
Think of when ice cubes are made. A tray full of water is put into the freezer, and when removed from the freezer, it is easy to notice that the water has expanded. This same thing happens when water gets into the ground under the pavement. If it has a chance to freeze, it will take up more space under the pavement, and the pavement expands, bends, and cracks, weakening the asphalt pavement. Then when ice melts, the pavement contracts and leaves gaps or voids in the surface under the pavement, where water can get in and be trapped. If the water freezes and thaws over and over, the pavement will weaken and continue cracking.
In warmer climates, not subject to freeze-thaw cycles, the problem begins with heat-caused deterioration. Cracks from the heat allow water in, eroding the sub-surface layers. In either case, an air gap is formed in the sub-base of the pavement.
As the weight of cars and trucks pass over the weak spot in the road, pieces of the roadway material weaken, which will cause the material to be displaced or broken down from the weight, creating the pothole.
How best to repair potholes?
First, be aware of some common problems that may occur during the repair. The asphalt being added to the pothole to make the repair is not the best quality. Some suppliers can make a virgin gravel mix, which is ideal. If that is not an option, make use of a rejuvenator–that is, something that is going to restore some of the oils and glue that have evaporated during the asphalt pavement’s aging process. Finding a mix with smaller rocks or more sand is also helpful for a nice patch repair.
Also, contributing to poor asphalt is overheating the paved area during the repair process. Anyone can set an infrared heater on an area and walk away for a half hour, intending to come back to two- to three-inches of pliable asphalt. However, what frequently happens is the top inch of asphalt is going to be burned to a crisp and whatever oil that was there to work with has vanished in the heat.
To heat deeper, heat the area for four- to five minutes and then scrape a layer off. Then, place the heater back on for another four- to five-minutes.
Another problem is called “push out.” This occurs when a contractor just runs the compactor over the repair area as quickly and as efficiently as possible. What is better for the patch is to pinch the edge or run the compactor around the edge six-inches on the old asphalt and six-inches on the new asphalt (give or take a measure based on the equipment). Pinching the edge deters movement or push out from the new, fresh asphalt.
The key to successful pothole repair is patience. A good patch repair is a process. If a contractor wants things to go quickly and doesn’t care, it will show in the results. If a contractor takes the time and follows the proper process, the result will be a good-looking, stable patch–but first, the contractor needs to care. Once someone cares about what they are doing, they will learn the process and learn the tricks that will allow them to be quick and good!
Krystal Strassman, DRS Paving, Fitchburg, Wis.
