Reconstruction and Rehabilitation Options for Asphalt Pavements
Having an asphalt pavement maintenance plan is crucial to maximize the life of your pavement. Yet, all great maintenance plans must come to an end. Eventually cracksealing, sealcoating, and patching will not adequately repair the distresses on your asphalt pavement. There are many options for reconstruction or rehabilitation of your pavement. Depending on the current condition, however, some of these options may not perform as well as others.
Asphalt Pavement Overlay
An asphalt overlay is a rehabilitation method by which 1.5 to 2.5 inches of new asphalt pavement is placed over the existing pavement. If the pavement has curbs, the existing pavement should be edge-milled to allow for the overlay to match the existing curb. Overlays are recommended for pavements approximately 12 years old and still performing well. Overlays are susceptible to reflection cracking, which are cracks that reflect upward from the existing pavement (below the overlay). Areas with fatigue (alligator) cracking or potholes should be corrected with asphalt patching prior to an overlay.
Milling the Pavement Surface and Overlay
This rehabilitation method uses an asphalt pavement milling machine to remove 1.5 to 2.5 inches of the entire existing pavement surface. Next, the milled surface is overlaid with new asphalt pavement. A mill and overlay is recommended for pavements approximately 12 years old and still performing well, but milling also allows for the correction of drainage or asphalt deformation issues. A mill and overlay is also susceptible to reflection cracking. Areas with fatigue (alligator) cracking or potholes should be corrected with asphalt patching after the milled surface is cleaned and inspected, prior to the overlay.
Removal and Replacement of Asphalt Pavement
Remove and replace is a reconstruction method that removes the existing asphalt pavement full depth leaving behind the aggregate base layer. New asphalt pavement is used to replace the removed section. Asphalt pavements that are very old and deteriorated but also have the proper aggregate base strength are ideal for remove and replace. Remove and replace completely removes the asphalt distresses; therefore, the new pavement is not susceptible to reflection cracking. Additional depth of aggregate base may be removed to correct drainage issues or allow for a thicker (stronger) asphalt pavement to be replaced.
Full Depth Reclamation (FDR)
Full depth reclamation is a reconstruction method where the existing asphalt pavement is pulverized and blended with the aggregate base and some of the subgrade soils to create a new base material. FDR is typically performed on the top 8 to 12 inches of the pavement structure. Some of the newly created base material may need to be removed to make room for the new asphalt pavement layer. FDR is a sustainable choice, as it greatly reduces the amount of trucking that is required.
Stabilized Full Depth Reclamation (SFDR)
Stabilized full depth reclamation is performed similarly to normal full depth reclamation, but cement or asphalt emulsion is introduced into the blend to stabilize and strengthen the new base materials. Grading of the stabilized base materials must be performed quickly before it is allowed to harden, and the final stabilized product is a much stronger base for the asphalt pavement. Stabilized reclamation is recommended for pavements with poor subgrade soils or drainage issues below the pavement.
Full reconstruction is the excavation of all asphalt pavement, aggregate base, and subgrade soils to a depth that is equal to the thickness of the new pavement design. The new pavement structure is then rebuilt by placing the new aggregate base and asphalt pavement layers. Full reconstruction is recommended for pavements that were originally under designed and didn’t last to its expected service life.