National Concrete Pavement Technology Center

Project description

Ultra-high-performance concrete (UHPC) represents the next generation of concrete, with a strength 3-4 times greater than traditional concrete (100-120 MPa as opposed to 30-40 MPa). However, most of the commercial UHPC mixes are proprietary and expensive. In this project, the authors document the development of nonproprietary, cost-effective UHPC mixes primarily using locally sourced or pre-qualified materials in Illinois. The research utilizes the modified Anderson and Andreasen packing model to establish a new parameter: “packing factor” that has a significant influence on the design and performance of multi-binder UHPC mixes. Initially, 19 UHPC mixes without fibers are analyzed for their rheological, mechanical, and durability properties, demonstrating promising results. Specifically, the authors obtain self-flowing capabilities with minimal high-range water reducer (HRWR) usage (<1% by wt.%), a turnover time of 7–10 minutes, and a significant reduction in cement content (47% Type IL and the remaining 53% supplementary cementitious materials (SCMs) by volume) while maintaining superior compressive strengths (~120–150 MPa, 17.2–21.8 ksi @ 28 days). Then, optimal mixes, particularly M18 and M19, are evaluated with fibers, achieving compressive strengths exceeding 150 MPa (21.8 ksi) at 28 days and exhibiting open porosity under 2%, and have shrinkage rates below the target threshold (<800µξ @ 91 days). Finally, effective particle packing resulted in UHPC mixes costs of ~$400/m³ (~$308/yd³) without steel fibers and ~$590/m³ (~$454/yd³) with steel fibers, enabling cost-effective, optimal UHPC for deployment by the Illinois Department of Transportation.