Better concrete mixes for rapid repair in Wisconsin : research brief.

The Wisconsin Department of Transportation (WisDOT) uses high early strength (HES) portland cement concrete in its rapid-repair CIP operations. The mix has a high cement content, accelerators, superplasticizers, air entraining admixtures and other mixture constituents that give it high strength gain and a fast curing time but also makes it more susceptible to high shrinkage and inadequate air void systems. This repair strategy costs less up front than precast patches but has a potentially shorter service life if the CIP is not optimal. The goal of this research was to identify strategies to reduce life-cycle costs by evaluating the performance of existing rapid-repair pavements and identifying mixtures with longer service lives capable of withstanding Wisconsin’s punishing freeze-thaw climate. Methodology Wisconsin concrete suppliers were surveyed to obtain information on rapid-repair mix designs, challenges and approaches. A field review of 12 recent rapid-repair pavement projects in Wisconsin evaluated field performance. Based on information from the field reviews and informal survey, 13 rapid-repair mixture candidates were proposed, made and tested in the lab.