Potholes in the road come from cracks in the roadway that fill up with water, freeze and thaw. When you don't roll or compact asphalt properly, these cracks can occur, along with severe rutting from the weight of vehicles. One way to keep these surface problems at bay is to follow the proper way to roll asphalt during installation.
Fill the water tanks on the rollers if they are not already full. The water tank on the pneumatic roller, or rubber tire roller, needs a release agent mixed into it to keep the hot asphalt from sticking to the rubber tires.
Position a 12-ton to 15-ton vibratory double drum roller behind the asphalt paver. Use the roller in static mode if the asphalt is tender, or made with small aggregate, and the mat depth is 2 to 3 inches. Use the roller in vibratory mode when the asphalt is less tender, made with large aggregate that produce a 4 to 6-inch thick mat.
Break down the hot asphalt with the double drum roller. You can back away from the paver slightly to let the asphalt cool somewhat before you begin to roll it. If the asphalt is too hot, the roller will push the asphalt rather than compacting it.
Tighten the scrapers to the drums as much as possible. Turn on the water pump and wet the entire drum -- this keeps the asphalt from sticking to the drums.
Follow the breakdown, double drum roller with a pneumatic or another double drum roller. Continually wet the drums on the rollers and use the water and release agent mix to keep the hot asphalt from adhering to the drums and rubber tires of a pneumatic roller until the tires get hot.
Roll the asphalt behind the mid roller, pneumatic or double drum, with another double drum roller until all marks are out of the pavement and the asphalt cools to 79.4 degrees Celsius. This finish roller takes the lines out and finishes the mat with a smooth appearance.
Position a 2-ton to 5-ton double drum roller behind the asphalt paver.
Compact the asphalt with one roller, unless it cannot keep up with the paver and the mat temperature drops below 79.4 degrees C without a 95-percent compaction.
Finish the rolling with another small double drum roller to remove lines and smooth the mat.
- Asphalt comes out of the screed at a compaction of 75 to 85 per cent, depending on the size of the paver. The initial breakdown roller will compact the asphalt most of the way to reach about 90 per cent compaction range. The mid roller and finish roller compact the mat to a desired or required compaction of up to 96 per cent, per governmental highway and roadway stipulations.
- You need to complete the rolling of asphalt while the mat is above 79.4 degrees Celsius.
- Some small driveway applications only need one roller to properly roll asphalt.
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