Asphalt Over Concrete

The unprepared sub base.

Asphalt over concrete.

Unfortunately when asphalt driveways are poured over concrete resting on an unstable base the resulting asphalt pour is prone to instability. This will most commonly occur during expansion and contraction due to heat and or freeze thaw cycles. Concrete itself is very stable and strong so no matter what it is poured over the slab is going to be solid when it hardens. It will however require a little more maintenance than a typical asphalt overlay.

Does concrete provide a solid base. Concrete is a great base material because it is stable and allows for excellent compaction of the asphalt above. An asphalt overlay is cheaper to install than replacing concrete and can provide a smooth ride over deteriorating concrete. Asphalt paving contractors frequently use asphalt over concrete on interstates state highways and city streets concrete provides an excellent base for the asphalt which must have a well compacted stable foundation to yield superior results.

Therefore concrete is often used as a bridge over unstable ground. To save time and money many states and municipalities use a road repair technique known as whitetopping the process of pouring concrete over asphalt rather than removing the existing asphalt. When concrete deteriorates it draws and holds moisture. Asphalt lasts 20 25 years while concrete lasts 30 40 years.

The truth about asphalt over concrete. Homeowners can benefit from this whitetopping technique to reduce labor costs and time when replacing worn asphalt driveways. In addition you do have an alternative paving method that may surprise you. But there are issues as you might expect.

Laying asphalt over concrete creates two layers to worry about. Asphalt requires a well prepared stable subbase otherwise the resulting pavement will be subject to instability and cracking. Blacktop can be successfully installed over concrete. If something is wrong with either of these layers it will show through the asphalt.

Applying an asphalt overlay to a concrete surface is a common practice. In fact many miles of concrete roads are paved over with asphalt every year. However it is important that you understand there are potential side effects and things to watch out for when paving over concrete. Asphalt overlay is an option for some asphalt surfaces that are in disrepair but paving asphalt over concrete comes with some catches.

How do brick and stone pavers compare to concrete. One positive aspect of installing blacktop over concrete is the concrete provides a firm base for the flexible asphalt paving. Laying asphalt over concrete will likely lead to this new asphalt forming cracks in the same spots that the concrete expansion joints have cracked below.