Mixture design methods for ultra-high-performance concrete - a review

A highly efficient mixture design should have a good balance among workability, strength, durability, economic efficiency, and sustainability. Ultra-high-performance concrete (UHPC) is a relatively novel composite material with ultra-high strength, high toughness, and superior durability, although new solutions are constantly being developed. Previous mixture design methods for normal concrete and high-performance concrete involve a series of trial tests and empirical analyses, which cannot be directly applied to UHPC without modification. This paper reviews four commonly used mixture design methods, including close packing methods based on dry and wet packing densities, rheology-based method, statistical analysis method, and artificial neural network (ANN) model, according to design principles. The design procedures of these methods and the effect of mixture proportioning on the key performance of UHPC are presented and discussed. The advantages and disadvantages of these methods are finally compared. Depending on the actual production situation and performance requirements, an appropriate method should be chosen to develop UHPC with specified requirements. Integration of two or more methods can serve as a good approach to deal with the complexities of UHPC mixture design by exerting each method's advantages.