Bonded concrete overlay

UNDER CONSTRUCTION

Bonded concrete overlays are a type of concrete overlay that can be used as a strategy for preventive maintenance as well as minor and major rehabilitation of existing pavements in good to fair condition. These overlays are a cost-effective solution to add structural capacity and eliminate surface distresses while still utilizing the existing structural capacity of the pavement below.

Bonded concrete overlays are typically between 2-6 in. and act as one monolithic pavement with the existing surface. For this reason, the bonding between the existing pavement and the overlay is crucial. The existing pavement is still utilized to carry a significant portion of the load. Thus bonded overlay projects are designed to maintain the bond between the overlay and the existing pavement.

There are a number of factors that affect the performance of the new structure and they include the structural integrity of the underlying pavement, the effectiveness of the bond, the ability of the two layers to move monolithically to maintain the bond, and the overlay jointing and curing techniques. (still revise)

REVISE: Bonded concrete overlays are relatively thin (2–6 in. [50–150 mm]). Bonded together, the overlay and the existing pavement perform as one monolithic pavement. Bonding between the overlay and the existing pavement is essential. The bond ensures that the overlay and existing pavement perform as one structure, with the original pavement continuing to carry a significant portion of the load. All bonded overlay projects, therefore, are carefully designed and constructed to achieve and maintain a bond between the overlay and the existing pavement.

Factors that affect the performance of the resurfaced pavement include the structural integrity of the underlying pavement, the effectiveness of the bond, the ability of the two layers to move monolithically to maintain the bond, and overlay jointing and curing techniques.

The key to achieving desired performance is to ensure the two structures—the existing pavement and the overlay—behave as one structure. Therefore, it is important to understand movement-related properties, such as expansion and contraction properties, of both the existing pavement and the overlay. For example, for a bonded concrete overlay of an existing concrete pavement, the coefficient of thermal expansion (CTE) of the overlay concrete mixture should be similar to or less than that of the existing concrete pavement.

Most bonded overlay projects are more challenging than unbonded overlay projects. Therefore, it is important to pay close attention to details in this guide.