National Concrete Pavement Technology Center

Project description

Recent research supported by the Wisconsin Department of Transportation (WisDOT) concluded that concrete produced with reduced cementitious materials content had an adequate durability; however, tested mixes frequently demonstrated poor workability. As a result, a need was identified for a multi-faceted approach to optimize the mixture proportions for low-slump concrete in pavements in order to realize the benefits related to reduced cementitious material content. The reported approach includes the use of supplementary cementitious materials (SCMs), optimized aggregate gradations, and the use of superplasticizers (high-range water reducing admixtures). Current WisDOT practice minimizes the use of portland cement through replacement with SCMs, but does not address the use optimized aggregate gradation or superplasticizers. Therefore, additional research was conducted to support the development of specifications inclusive of these factors to improve the performance and sustainability of concrete paving mixtures used in Wisconsin. This research project evaluated the feasibility of expanding current specifications to incorporate the optimized superplasticized concrete in sustainable concrete paving applications. Furthermore, the goal of the reported study was to produce the guidelines for optimizing concrete mix design by evaluating the performance of a range of concrete mixtures. The performance evaluation of optimized concrete included the workability (slump), air content, compressive and flexural strength, freeze-thaw resistance, and rapid chloride permeability in accordance with the relevant AASHTO or ASTM standards. Finally, the reported research recommended the selection of aggregate gradations and superplasticizing admixtures in low-slump concrete with reduced cementitious materials intended for paving applications.