There are some challenges when paving the narrow end of each pie piece and we’ll cover those later. But for now determine how many passes you will need to get to the final pass on the first half of the project. This final pass should be 8 feet or 12 feet wide (basically it should match up with half the width of the road entering the cul-de-sac). That final pass should create a butt joint at the bottom of the circle from which you can start paving the road that leads in to the cul-de-sac.
Getting Hot Mix Into the Hopper
So you’ve got the plan, you’ve done the layout, and you’re ready to pave your starter mat. The only question you have left is “How are you going to fill the paver hopper?” Getting the material to the paver is one of the most difficult challenges when paving in a circle, especially on the first pass, because you can’t have the truck-paver interface on a tight radius.
If you have a material transfer vehicle and the job is big enough to warrant hauling it to the site, your problem’s solved: use it. But most contractors don’t have one and don’t have access to one so the options are either moving the paver to the truck so the truck can dump mix into the hopper, then driving the paver back to continue paving, or to use some type of loader to haul material from the truck to the paver while the paver stays in place.
Experience and testing has shown it is always better to leave the paver in line where it’s paving and bring the mix to it. Each time you move the paver, lifting the screed from the surface, you create a bump in the finished mat; You also create the potential for a cold joint at the point where the screed was lifted and set back down.
By far the best process is to leave the paver in place and keep the hopper filled using a bucket machine or skid steer loader. This way even if you have to stop paving to wait for mix, which in this type of job you probably will, you can leave the screed on the surface, eliminating the cold joint and eliminating or at least significantly reducing any bump in the mat.
Paving the Starter Mat
To begin paving start at the top, opposite the road entering the circle, and pave one paver width along the curb to the road opening (Figure 1). This first pass is the starter mat, or bench.
Because of the way pavers are built the operator can’t see the curb over the front of the machine so he can’t use that as a guide to steer. It helps the paver operator if hash marks are sprayed onto the pavement marking the inside of the pass because he can see those marks and steer by them, keeping the radius on track and not bumping against the curb.
Also, the shape of the paver and its screed require that the paver be 12 to 24 inches from the curb as it moves along the radius. This gives the screw man at the back an opportunity to work the extensions and depth to make sure a quality mat is placed along the curb. You need to maintain enough distance from the curb to allow the screw man to make up that distance while allowing the paver operator to complete the pass – all without scraping the concrete curb.
“Filling in the Pie”
You’ve planned out the job, used stringline or paint to mark the passes on the pavement, and you’ve placed your starter mat and compacted it to within a few inches of its edge. Now fill in the half circle by following the passes you’ve marked out (Figure 1).
The difficulty here isn’t getting the material into the hopper, it’s producing a quality mat in a process where the width of the paving changes significantly over a very short distance. It’s a challenge because you’re paving pie-shaped pieces and when the screed gets to a point where there’s not enough material the screed will drop, resulting in an uneven pavement and poor quality job. Drainage also could be affected.
So it’s important to maintain correct width with head of material to prevent the screed from dropping. The most-effective way to do that is to lock up one of the screed lift cylinders. This essentially prevents the screed from floating and enables you to maintain uniform depth from side to side of the screed as you pave.
Another option is to overlap your paving passes but that creates issues with the mix and generally results in a poor-looking job. (Some contractors opt to pave by hand, but when paving by hand you can never get the same density or quality. Basically anything done by hand is inferior to what a screed can do.)