Introduction to Overlays

Thin concrete overlays have been successfully used in the United States for extending the life of existing concrete, asphalt, or composite pavements. These overlays can accommodate a variety of needs, such as extending performance lives by as much as 15 to 20 years, meeting rapid construction requirements, and conforming to any specific traffic management constraints (Tayabji et al. 2009). In addition, a properly designed and constructed concrete overlay requires little maintenance over its service life, resulting in reduced life-cycle costs. Concrete overlays less than 6 inches (152 mm) thick are commonly identified as “thin” concrete overlays, while the term “ultra thin” is sometimes used to refer to overlays less than 4 inches (102 mm) thick.  These thin overlays  also  feature  smaller slab sizes, with 6 ft by 6 ft (1.8 by 1.8 m) panels commonly used. This course provides a review of thin concrete overlays, and is supplemented with a summary of four case studies to illustrate the range of applications for thin concrete overlays.