There was a time when concrete was more popular than asphalt for constructing pavements of all types, including parking lots. Concrete is a strong, long-lasting material that can support heavy loads and high traffic for decades. However, a concrete parking lot is more time-consuming and costlier than a comparable asphalt parking lot. Furthermore, when a concrete lot fails, the demolition and reconstruction can also be relatively slow and expensive. Therefore, some property managers and owners wonder whether they can have a contractor place asphalt paving on top of the concrete. In many cases, an asphalt contractor can indeed pave over concrete. Most contractors refer to this procedure as an asphalt overlay. However, overlays are not suitable for all concrete pavements, and there are certain consequences that you should consider.

What Is an Asphalt Overlay?

When a paving company installs asphalt over an existing pavement, the contractor will refer to it as an overlay. Depending on the specific pavement, an overlay is typically between two and three inches deep. When contractors install overlays on existing asphalt pavements, they usually mill the pavement first. This means that they grind away the asphalt pavement to a depth that corresponds to the depth of the overlay. One reason for milling the existing pavement is to retain curbs, drainage grates, and other features at their original elevations. However, when placing asphalt paving on Houston concrete pavements, contractors cannot mill the existing pavement. Therefore, the overlay will increase the thickness of the pavement, and this will affect the elevation of features. Sometimes, the asphalt paving company can remedy the issue, but it will likely increase your cost if it is even possible.

What Qualities Must a Concrete Parking Lot Possess for an Asphalt Contractor to Install an Overlay?

First and foremost, the existing pavement must have a stable, strong foundation. Otherwise, the concrete can shift underneath the overlay, creating cracks or breaking the bond. The problem is that contractors providing concrete paving in Houston often do not pay much attention to the foundation. Unlike asphalt, concrete can bridge any instability in the subgrade without affecting its ultimate hardness. Furthermore, the alignment of the individual concrete slabs must be relatively correct. Slabs that shift in either the horizontal or vertical direction will damage the overlay.

What Are the Potential Consequences of Having an Asphalt Company Pave Over a Concrete Parking Lot?

Besides the issues discussed in the previous sections, the most significant consequence is the potential for reflective cracking. If you look at your concrete parking lot, you will notice that there are expansion joints between the slabs. Expansion joints allow the slabs to expand and contract in extremely cold or hot weather. These joints will still be functional underneath the overlay, and the expanding joints could be reflected in the asphalt as cracks. Reflective cracking could also occur at other spots in the concrete pavement that have incurred damage.

To Learn More, Contact the Concrete and Asphalt Experts at Marathon Solutions Group

We are a leading paving company offering both asphalt and concrete paving services to clients throughout Houston and Harris County. Our paving services include asphalt overlaying and paving, concrete installation, asphalt and concrete pavement repairs, asphalt milling, parking lot striping, bollard installations, asphalt crack repairs, parking lot signs, thermoplastic markings, asphalt sealcoating, and marking removal. Our reputation for craftsmanship, service, integrity, and professionalism is exemplary. If you would like to request a free job quote, submit the form online, call 800-879-1147, or email