Can You Put Asphalt Over Concrete?
Remember when you were young and you asked your teacher, “Can I go to the restroom?” Most likely, you got the reply, “I don’t know. CAN you?” We learn pretty early on that “can” is a tricky word. When I’m frequently asked, “Can I put asphalt over concrete?” I always say that the simple answer is, “Yes.” In fact, miles and miles of concrete roads are paved over with asphalt every year, and concrete can be an excellent, stable base material for asphalt pavement. But … it’s not always the best idea to lay asphalt over concrete. If you are thinking about whether or not to put asphalt over your existing concrete pavement, consider the following factors:
Concrete Expands and Contracts.
Unlike asphalt, concrete pavement has expansion joints. These joints are areas designed to allow the concrete to shift, in order to relieve any stresses on the surface in a stable way. It’s important to note that, even with reinforcing measures, if you pave asphalt over concrete, the asphalt is likely to eventually crack at the joint areas. These cracks are not a failure of the pavement, but they will be present and require prompt attention so that they don’t turn into more serious damage.
Concrete May Not be Stable.
Concrete hardens on its own no matter what it is poured over. For this reason, concrete is sometimes poured over an unstable base. If this is the case, the slabs can shift and pivot overtime, as the concrete cracks at the expansion joints. When paving asphalt over concrete, you must ensure that there is a stable base and that the concrete slabs have not pivoted.
The Sub Base Should be Compact
With concrete pavement, compacting the sub base is not usually standard procedure, so there’s really no way of knowing what’s under the concrete until it’s dug up. The sub base may be compact, but it’s likely that the ground underneath the concrete pavement has shifted or sunk in. If you put asphalt over concrete that shifts, cracks will appear in the new asphalt. One way to judge is to see if your concrete pavement is crack-free and no slabs have tilted. With concrete in good condition, the asphalt overlay will work as well or better on it than other sub bases.
How to Put Asphalt Over Concrete
If you decide to lay asphalt over your concrete pavement, there are key steps your asphalt contractor should take:
- Create a uniformly thick base if it doesn’t exist
- Clean and mill (grind) the concrete to ensure the new asphalt overlay will have a good bond to the concrete
- Install paving fabric over concrete expansion joints
- Use proper adhesive and hot mix asphalt
DC Construction Services has the knowledge, experience and expertise to pave and maintain your asphalt pavement to ensure its integrity and longevity. If you are considering putting an asphalt overlay on your concrete pavement, protect your investment and go with a paving partner you can trust. Contact the DCC team.