Experimental study and prediction of uniaxial compression behavior of the novel UHPC reinforced with BFRP minibars

In order to gain the stress–strain relationship of ultra-high performance concrete (UHPC) reinforced with basalt fiber reinforced polymer (BFRP) minibars under uniaxial compression, nine kinds of UHPC mixtures with BFRP minibars were designed. In addition, other three kinds of UHPC mixtures were designed to study the effect of fiber modulus on uniaxial compression behavior, the UHPC which were reinforced with no fiber, polypropylene (PP) fibers and steel fibers, respectively. The flowability, porosity, elastic modulus, compressive strength and toughness of UHPC were systematically tested and analyzed. Based on the test results, BFRP minibar significantly enhance the uniaxial compression behavior of UHPC, the stress–strain relationship was gained and it was expressed by a classical model with a good agreement, resulting in a promotion of the structural design for UHPC structures. The compressive strength increased with fibers modulus, content, aspect ratio, and bonding strength between UHPC and fibers. A semi-empirical model with a relative error rate less than 15% was proposed for compressive strength prediction, the model which was based on fibers modulus, content, aspect ratio, and bonding strength. The findings based on this research could enrich the technical basis for the performance design of UHPC in practical applications.