Concrete Overlays for Pavement Rehabilitation (ACI 325.13R-06)

Description

Hydraulic cement concrete overlays are used as a rehabilitation technique for both existing concrete and asphalt pavements. Concrete overlays offer the potential for extended service life, increased structural capacity, reduced maintenance requirements, and lower life-cycle costs when compared with hot-mix asphalt overlay alternatives .Concrete overlays have been used to rehabilitate existing concrete pavements since 1913 and to rehabilitate existing asphalt pavements since 1918 (Hutchinson 1982).

Beginning around the mid-1960s, many highway agencies began to search for alternative means of rehabilitating existing pavements, and the use of concrete overlays increased significantly (McGhee1994). In the 1990s, there was an even higher increase in the use of concrete overlays, spurred by improvements in concrete paving technology. For example, the use of zero-clearance pavers, fast-track paving concepts, and high-early-strength concrete mixtures greatly increased the ability of concrete overlays to serve as a viable rehabilitation alternative. Parallel with the increased use of concrete overlays, significant research aimed at advancing the state of the knowledge of concrete overlays was conducted.

One impetus for this research was the Intermodal Surface Transportation Act (ISTEA) of 1991, which included a provision under Section 6005 allocating designated funding for the assessment of thin bonded concrete overlays and surface lamination technology. The goals of the assessment were to evaluate the feasibility, costs, and benefits of the techniques in minimizing overlay thickness, initial laydown costs, and time out of service, and also to maximize life-cycle durability. As part of this effort, the Federal Highway Administration (FHWA)participated in funding 12 test-and-evaluation projects throughout the country (Sprinkel 2000).