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Asphalt overlays are typically used to extend the life of continuously reinforced concrete pavement (CRCP) because they can be placed in one or more layers while traffic uses the adjacent lane and can be opened to traffic in a short time. Hydraulic cement concrete overlays have also been used to extend the life of CRCP but have often not been considered an alternative to asphalt because of the higher cost and longer curing time.
In 2012, the Virginia Department of Transportation rehabilitated a 4.8-mi section of the westbound lanes of a CRCP on U.S. 58 in Southampton County using a 4-in-thick bonded concrete overlay and a 7-in-thick unbonded concrete overlay with a 1-in asphalt separation layer. The four-lane, divided primary highway is an 8-in-thick CRCP placed over a 6-in cement-treated aggregate layer. Saw cutting was used to form joints at 6 ft by 6 ft panels for an unbonded overlay, and tie bars were used along the centerline of the pavement and along both shoulders. A concrete overlay was placed on the shoulders of the unbonded overlay, and asphalt was placed on the shoulders of the bonded overlay.
Two layers of asphalt with a total thickness of 5 in were placed on a 9.75-mi section of the eastbound lane of U.S. 58, which provided cost information that was used to compare the alternatives. Since traffic management was very different for the two projects, definitive conclusions on the total cost of asphalt versus concrete overlays could not be drawn. On the basis of material costs alone, concrete and asphalt can be competitive options for extending the service life of CRCP.
Construction of the concrete overlays was successfully executed on time. The concrete was of high quality with good strength and low permeability. The bonded overlay is well bonded. The ride quality was much better than for the original pavement. Using the initial cost of materials in-place, the cost of the bonded and unbonded overlays was approximately the same, at an average of $36 to $38 per square yard. The unit cost of patching concrete pavements is approximately 6 times the cost of the bonded concrete overlay and approximately 4 times the cost of an unbonded overlay.
VDOT’s Materials Division should consider the use of bonded concrete overlays to extend the life of CRCPs that are in good condition and need little patching (<10%) prior to placement of the overlay and should consider the use of unbonded concrete overlays as an alternative to patching to extend the life of CRCP that needs more than 10 percent patching. Further, the Materials Division should advertise overlay projects allowing alternate designs using stone-matrix asphalt and hydraulic cement concrete to determine if they are competitive alternatives. VDOT’s Traffic Engineering Division should explore innovative traffic management plans for pavement rehabilitation to reduce maintenance of traffic costs.
Authors: Michael M. Sprinkel, P.E., Celik Ozyildirim, Ph.D., P.E., M. Shabbir Hossain, Ph.D., P.E., Mohamed K. Elfino, Ph.D., P.E., Chung Wu, Ph.D., P.E., and Affan Habib, P.E.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=”1/1″][button new_tab=”yes” icon_position=”left” special_style=”no” border_radius=”2″ three_d=”no” size=”default” color=”default” title=”View Report” link=”http://www.virginiadot.org/vtrc/main/online_reports/pdf/14-r16.pdf”][/vc_column][/vc_row]