About Spray Patching
Because most people have never heard of spray patching, we thought it might be best to give you some information on it.
History in Virginia
Spray patching has been around since the early 1980’s. However, it was not until the late 90’s that it was utilized in Virginia. We started patching in 1997 and VDOT purchased a truck that is used in the western part of the state in 1998. Since then, it has become a common tool for addressing potholes and other pavement repairs in several VDOT districts.
How it works
The spray patching process combines two materials, emulsified asphalt (tar) and stone. Spray patching equipment is either mounted to a trailer or a truck chassis. The truck mounted units which we have, carry both materials on one truck in separate compartments. From the cab of the truck, the operator controls a boom positioned on the front to do the following:
- Initially the repair area is blown clean of dust and debris. This is done by the truck’s high volume blower conveying air through the boom and down onto the pavement.
- Once the area is blown clean, a layer of tar is applied to the road surface.
- This tack coating seals the area and bonds the patch to the road.
- Next, stone is conveyed through the aggregate line. As it is sprayed out of the boom it is coated with tar.
- The repair is filled until it is level with the surrounding area. The tar is then turned off and the patch is covered with dry stone.
Advantages
The spray patching process provides many advantages. Some are as follows:
- The stone we use is small. This allows us to patch shallow spots as well as deep repairs.
- The tar tack coat is applied to the pothole and also the surrounding area. This seals the hole and any cracked and broken area around it. .This prevents water from reentering the patch.
- Many types of pavement problems are repairable with spray patching. Repairs range from something as thin as cracks to deep shoulder erosion. We can patch potholes, surfacing raveling, alligator cracking, sunken cross pipes, utility cuts, tapering onto and off of bridges, shoulder drop offs. Basically, any repair you might fill with plant mixed asphalt, concrete, stone, or a surface treatment we can repair with spray patching.
- Patching can be done successfully at all temperatures. Yes, we prefer 75 degree days, but we know we can patch successfully at 8 degrees.
- Minimal disruption to traffic flow - one operator fills the holes from the cab.
- No job is too small, our materials are stored separately and combined as used.
- Patches last a long time – We see patches that were done prior to 2001. In that year, we started purchasing our stone from a new vendor. The color of the stone is different, which makes patches before 2001 easy to identify.
Disadvantages
Our equipment doesn’t dig holes. Some repairs, due to base problems, need to have the road material extracted and the base fixed before the area can be repaired. If you walk or drive on an area and it pushes down on one side and comes up on the other, you have a need we can only cover up, not properly fix. However, once this area stops moving, basically dries out, we can patch it. This will level it and stop additional water from penetrating the base.
