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Published: 2010

Total Pages: 20

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As the US Highway system ages and available funding diminishes, transportation agencies are looking for effective methods for preserving and extending the life of existing pavements. These agencies are also being encouraged to minimize construction times and reduce the impact to the traveling public. Currently, the most common method of rehabilitating an existing roadway surface is through an HMA overlay; however, high oil prices have caused designers and agencies to consider other methods. One alternative to the traditional HMA overlay is a concrete overlay. The Iowa Department of Transportation (Iowa DOT) and Iowa counties and cities have completed about 1,000 miles of concrete overlays that are in use and are serving the traveling public today. Despite the completion of hundreds of projects, some agencies are reluctant to use concrete overlays, believing that they are expensive, difficult to build, and have limited application. To address these concerns, the National Concrete Pavement Technology Center at Iowa State University developed a guide document to assist engineers in concrete overlay design and construction. The Guide to Concrete Overlays was published in September 2008 and includes detailed information on evaluating existing pavements as concrete overlay candidates, selecting and designing the appropriate type of concrete overlay, and guidance on concrete overlay construction. Since the publication of this guide, the need has arisen to develop methods to improve concrete overlay efficiency utilizing current technology, investigate innovative materials for use as bond breakers, and reduce the inconvenience to the public with improved methods of traffic control and increased opening time.