Feasibility Study of Development of Ultra-High Performance Concrete (UHPC) for Highway Bridge Applications in Nebraska
Date of this Version
Mendonca, F., El-Hhier, M. A., Morcous, G., and Hu, J. (2020). Feasibility Study of Development of Ultra-HIgh Performance Concrete (UHPC) for Highway Bridge Applications in Nebraska. NDOT Research Report SPR-P1(18) M072.
Ultra-high performance concrete (UHPC) is a new class of concrete that has superior mechanical, durability, and workability properties that far exceed those of conventional concrete. To achieve these properties, a specific mix design with a very dense internal structure, fiber reinforcement, and low water-to-binder ratio (w/b) is commonly used. The goal of this research is to develop a non-proprietary UHPC mix with constituent materials that are readily available in the state of Nebraska for bridge construction applications. In developing this mix, the particle packing model is used, and an experimental study of the impact of various design parameters on the key properties of UHPC is conducted. Multiple series of UHPC mixtures are investigated with different types and quantities of aggregate, fibers, cement, supplemental cementitious materials (SCMs), high range water reducer (HRWR), w/b, total binder content, and mixers. Mix design with type I/II cement, 8% of silica fume (by mass of binder), and 30% of slag (by mass of binder) is recommended. The developed mix exhibits sufficient flowability and stability to ensure the successful implementation in bridge components and connections. A comprehensive evaluation of mechanical properties demonstrated that the mix exhibits excellent mechanical properties, including compressive strength, modulus of elasticity, Poisson’s ratio, flexural strength, splitting tensile strength, direct shear strength, slant shear strength, and bond strength. The developed mix also exhibits excellent durability properties, including mass loss of less than 1% based on freezing/thawing resistance test, very low chloride ion penetration based on surface resistivity test, and no cracking based on restrained shrinkage test. The unit cost of the developed mix is approximately $682 per cubic yard, which is approximately one-third of the current commercial products. The batching, handling, placing, and curing of the developed mix was demonstrated in a field-scale panel connection casting, which resulted in a satisfactory performance.