Potholes, cracks, and loose gravel on the surface of your asphalt parking lot are all worrying signs. The good news is that often these damages are no more than surface deep, so you may not need to replace the paving just yet. Instead, an asphalt overlay can repair the damages and make the parking lot look and perform like new again.
Cleaning and Repair
All overlay jobs begin with cleaning and repair. The entire lot will be cleared of loose debris. Steam sweeping may also be used if there are lots of oil and fluid stains that need to be removed, but generally, the main focus is on removing loose gravel, blown-in debris, and weeds that are growing in the cracks.
Next repairs are made. Surface cracks are ignored, but cracks or potholes that penetrate beyond the top inch or two of asphalt will require full patching. Generally, this is done with a hot mix asphalt patching compound. The hot mix bonds better with the existing asphalt that surrounds the patch to create a repair with maximum stability.
Once the repairs are completed, the surface of the asphalt must be prepared for the overlay. This involves grinding down the surface of the paving, usually by a few inches depending on the existing thickness as the asphalt must not be ground down to the base material. Grinding doesn't just make room for the overlay, it also creates a rough surface that the fresh asphalt can better adhere to.
A tack course is applied over the surface after grinding. This is an asphalt and adhesive mix that is designed to help the asphalt overlay adhere more fully to the existing paving. A thin leveling course of asphalt may be applied over the initial tack course if it's necessary to smooth out any uneven areas in the old paving. In this case, a second tack course is applied over the leveling course.
Finally, the overlay is applied. This is usually a thick layer of asphalt, often several inches deep. After application, it's smoothed and leveled. The new asphalt overlay usually requires one to two days for the initial cure. During this time it can be walked upon but shouldn't yet be driven on.
After the initial cure, parking lot striping can be painted on and the lot is again usable. It takes a few months for asphalt to cure appropriately, after which time it can be seal coated to protect it from weathering damage.
Contact a professional paving service to learn more about the overlay process.