Aug 22, 2022
Best Practices for a Smooth Mat on Your Overlay
Whether your crew must perform the “fill” portion of a mill-and-overlay or the county is only paying for a 1-inch overlay atop a suspect pavement, getting the basics right is what contributes to your success and full pay. Here we go.
Auger height affects the head of material, of course. To get the head of material right, the paver operator will set the paver speed and auger rotation so that mix reaches the center of the augers as it feeds under the tractor. Your mat depends on getting the head of material right. That means you want to train the crew to set up the augers for success; train them to get the center of the augers in the right space.
They have to start with a tape measure and the job specs. They need to know the depth they’re paving and the height of the pavement they’re matching. They need to know which part of the paver is the auger, and they have to understand which part of the auger is the head of its curl. These things are a given to you and me; make sure you point them out to new members of the crew so no one has to feel “behind the eight ball” asking what they are.
When you feel confident in your crew’s knowledge of the equipment, have them set the screed down and pull ahead of the pavement they’re going to match. Then have one of the screed operators measure from the augers to the ground with a tape measure. Is the bottom of the auger sitting 6 or 7 inches off the ground? That’s too high and the crew will end up fighting with too much mix as they pave. Instead, teach them to go with the rule of thumb that augers should be 2 inches above the existing mat. If they have a 2-inch mat to match, they want the bottom of the auger to be 4 inches off the ground. They should measure and set the bar appropriately.
Also teach them to measure from the head of the auger curl to the pre-strikeoff. This area/length should be 5 to 6 inches. If the augers have worn too much, the worker will see a larger space in there—6 to 7 inches—which will create the over-feeding problem as well. That’s one of the reasons it’s important to check the condition of the augers for thickness and wear.
Also remind your workers of the importance of cleaning the box, giving equipment a proper wash-down so the area isn’t dropping chunks of old, cold material into the hot, tested mix.
The training you give the crew before the overlay project starts will set them up for success and full pay at the end.