One of the more difficult paving jobs contractors encounter is paving a circle – in most cases a cul-de-sac. The difficulty arises because the tight radius of the circle does not match up well with the straight and relatively inflexible shape and configuration of the paving screed. That, combined with the need for effective drainage, can create headaches for contractors and property owners alike.
But here’s a “best practices” approach to get that troublesome job done. Where circles often are paved up to gravel or even grass, many are surrounded by concrete curb and gutter so that’s the job we’ll tackle in this article: an asphalt overlay on a cul-de-sac ringed by concrete curb and gutter. The curb and gutter defines the edge, generally provides sewer grates to remove water from the surface – and also creates difficulties for the paver operator and his team.
Drainage Governs Approach
As with any paving job, preparation and planning is 80% of the job’s success and possibly even more important when paving a circle. That’s because the planning of the job involves pie-shaped paving passes instead of just straight pulls.
But first things first: Drainage. As with any paving job you need to identify the way the water flows off the pavement, then you need to mimic that in your overlay. In a perfect world water would flow evenly from the center of the cul-de-sac to the edges in several directions. Sometimes the water flows from the center toward each side, and when paving circles around an island you will likely encounter drainage that sheets the water from the inside if the circle to the outside. Regardless of how the water flows you need to determine that prior to paving your project because the last thing you want is water pooling in the center of the cul-de-sac.
In addition to determining drainage you need to identify the crown, which should basically divide the circle in half from top to bottom and extend into the roadway. Your paving plan should make every effort to construct the crown in the final paving pass as your paver pulls out of the circle into begins paving the road.
Don’t Skip Layout
When paving a cul-de-sac or other circle some contractors like to pave the initial pass against the curb all the way around, then work off that first pass to “fill the pie.” The problem with this is the inside joint of the pass – the joint away from the curb – becomes cold by the time you are back to paving against it.
So a “best practices” approach to paving a cul-de-sac is to pave half the circle at a time. Identify the crown and work half at a time from the outside edge to the center; from the outside on one half to the crown and from the outside to the crown on the other half. That way your final paving path will be on the crown and at full width.
The key to any successful paving job is hot joints. You try to maximize the hot joints and minimize the cold joints because any time you’re paving against a cold joint you are creating compaction issues which eventually will result in pavement failure — cracking, water intrusion and more.
So to maximize the number of hot joints in the job you need to plan it out. The first pass will be against the curb, 8 feet or 12 feet wide depending on your machine, to create a bench or starter mat from which to work. Subsequent passes will be straight, but they will narrow as they reach the opening (bottom) of the cul-de-sac. It’s important to plan this paving out in as few passes as possible, reducing handwork and labor while maintaining the integrity of the mat.
The layout within the circle will depend on the actual width of the circle. So to plan the passes after the starter mat measure the width of the half circle at its widest part and at its narrowest part. Your paving widths will not be uniform (except for the last pull in each half – the center of the circle) and each pass to “fill the pie” will start wide and narrow at the bottom but you should try to maintain wider passes as much as possible.