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As jointed concrete pavements age, they typically experience panel cracking, joint or crack faulting, and surface distress. To maintain user satisfaction and safety, the agency or owner must identify the causes of the distress and consider types of feasible repairs, if any. These repairs range from partial to full-depth concrete repairs for spalled or cracked panels, to load-transfer and ride-quality restoration schemes for faulted cracks and joints. Retrofitting dowel bars into a distressed and faulted concrete pavement has become a proven technique for restoring or improving the capacity of jointed concrete pavements. The backfill materials and installation techniques used in retrofitting dowel bars must, however, be carefully designed. Numerous field and laboratory trials have been carried out in Minnesota in the recent past, allowing engineers and contractors to refine the installation techniques and materials necessary to produce long-lasting and effective projects. This paper provides a history of the development of best practices for retrofitting dowel bars into jointed concrete pavements located in the extreme climate of Minnesota. The performance of field test sections, up to 13 years old, are discussed in relation to dowel bar location, long-term load transfer capability, and durability of backfill materials. Implemented design changes based on results from accelerated loading laboratory studies are discussed. An effective installation method and materials testing process, required of contractors before constructing retrofit projects in Minnesota, is described. Retrofit dowel bar installation, in conjunction with restoration of the surface through diamond grinding, has been proven to significantly extend the capacity and serviceable life of many concrete pavements in Minnesota.

The Minnesota Department of Transportation (Mn/DOT) began building high performance concrete pavements (HPCP) under the FHWA TE-30 program in 2000. Since that time, Mn/DOT has adopted HPCP as the standard design for most high volume urban highways in Minnesota. This study describes the design features incorporated into high performance concrete pavements in Minnesota, and provides a history of changes that have evolved since 2000. A list of recent high performance concrete pavement projects and their unique design features are provided. Performance monitoring results, including ride quality, joint load transfer efficiency, and surface texture, are given for recent HPCP projects. While it is too early to predict the future performance of recently constructed HPCP projects in Minnesota, potential causes for reductions in the serviceability of 60-year design HPCP projects are discussed.