Now that prices for cement and asphalt have leveled off, thanks in part to skyrocketing oil prices-which basically puts both materials in a dead heat-infrastructure managers are rethinking their approach to overlay projects.
The latest edition of the "Guide to Concrete Overlay Solutions,"published by the National Concrete Pavement Technology Center at Iowa State University, is expected to be released by the end of the year. The new edition expands on the earlier edition, released in January 2007, which provides key elements of six major types of concrete overlays (both bonded and unbonded resurfacing of concrete, asphalt, and composite pavements).
The updated guide includes a flow chart and details the key elements of those overlays, taking readers from the initial visual inspection all the way through construction. It's designed to help infrastructure managers in the process of choosing the best types of pavement for their individual projects.
"We want to show the cost-effectiveness of concrete overlays both in the medium term and long term," says R. Scott Haislip, director of streets and roads for the American Concrete Pavement Association (http://www.acpa.org), which distributes hard copies of the guide. "We've always been able to compete with asphalt on a life-cycle cost basis, but only now are we able to compete at first cost."
Concrete's annual maintenance costs per lane mile are about 1/12 of those of asphalt, but only in the last several years have rising oil prices brought the materials costs in line for asphalt and concrete. In Michigan, for example, 20-year-life concrete was priced at about $16.50/square yard in 2003 but rose only slightly by less than $2 in 2007. By comparison, asphalt prices have jumped 70% in the last five years.
"Our advice to public works directors is to build a concrete overlay to see the value they're going to get out of it. It will eliminate the perception that (concrete overlays) are too hard to construct."
- Michael Fielding
Session: Optimization of Pavement Overlay Systems
Director Streets & Roads, American Concrete Pavement Association
Sun., Aug. 17, 2007