Bouncing often leads to these impact marks. Bouncing sometimes occurs when a crew tries to reduce the thickness of the asphalt layer by making numerous, slow vibratory passes. The compactor can only reduce the thickness of the layer so much. When the layer becomes dense, the drums will begin to bounce and leave impact marks.
If you begin to feel drum bouncing, or if you begin to see impact marks in the surface of the asphalt layer, you should adjust one or more of the following variables:
- Check the working speed to make sure you are operating in the range that produces 26 to 46 impacts per meter (8-14 impacts per foot).
- Switch to a lower amplitude setting.
- If available on the machine, switch to a higher frequency.
- Operate with one drum vibrating and one drum static.
- Operate in the static mode.
Eliminating bouncing, and overcoming other problems, are keys to successful compaction — and healthy bonus checks that boost your bottom line.