Resurfacing concrete pavements improves the quality of the riding surface and can increase the traffic-carrying structural capability of a roadway. Concrete and asphalt commonly are used for concrete paving resurfacing treatments.
A concrete overlay is a layer of concrete laid over an existing concrete pavement. For pavements in good structural condition, a “bonded overlay” is a layer of concrete pavement placed directly on top of the existing concrete pavement. In other situations, an “unbonded concrete overlay” is constructed with a thin layer of material, like asphalt pavement, that separates the concrete layers and reduces cracking.
In an asphalt overlay, a layer of asphalt is placed over the concrete pavement. Some agencies place a geotextile fabric over the concrete prior to asphalt paving to minimize the cracks and joints in the concrete pavement from reflecting up into the asphalt pavement.
Concrete and asphalt overlays effectively extend the useful life of concrete pavements. The Illinois Department of Transportation reports several interstate highway concrete overlay projects that performed well for more than 20 years before requiring major rehabilitation. IDOT also determined the useful life of an asphalt overlay of concrete pavement is about 10 to 12 years.
Selection of the appropriate overlay treatment requires an engineering assessment of the existing concrete, including the thickness and condition of the pavement and the severity of cracks and rutting. An engineering economic analysis of the life-cycle cost of each pavement overlay alternative is typically performed. During construction, close attention to surface preparation and the positioning of joints in a concrete overlay are critical to the success of the resurfacing project.