An overlay is the paving of a second layer of asphalt over present asphalt. An overlay can be done when the current asphalt is in good state but may have some problem areas. Contingent on the amount of cracking, disintegrating or lower areas, and those areas can be cut out, patched and then a new layer can be paved. An overlay should not be done on a driveway or parking lot that is relentlessly fractured, disintegrating, and curly or has plummeting, soft spots.
The new layer of asphalt will track the old asphalt cracks (deep cracking) and sprays in a very small period of time.
Prior to paving an overlay, a tack coat primer should be used. This is the glue that is used to adhere the new asphalt layer to the existing asphalt. Again, many contractors skip this step and have less than acceptable results.
Thin Asphalt Overlays for Pavement Preservation
Thin asphalt overlays are popular approaches to pavement preservation because of their ability to provide improved ride quality, reduce pavement distresses, maintain surface geometrics, reduce noise levels, reduce life cycle costs and provide long-lasting service. This document provides guidance on when to choose thin overlays, how to select materials and design the mixes, construction and quality control, and what type of performance benefits to expect.