Static Mechanical Properties and Microscopic Analysis of Hybrid Fiber Reinforced Ultra-High Performance Concrete with Coarse Aggregate

An orthogonal test was conducted to investigate the effect of hybrid fiber on mechanical properties ultra-high performance concrete (UHPC-CA) with coarse aggregate . It used design and manufacture 144 specimens for compressive strength, flexural tensile static elastic modulus test, SEM microscopic test. Considering mass replacement rate (10%, 15%, 20%, 30%), steel volume (0%, 0.5%, 1.0%, 1.5%), polypropylene 0.05%, 0.10%, 0.15%). The results show that fraction has greatest impact strength followed by substitution aggregate, smallest impact. For under compression, impact, fiber. Based analysis properties, modulus, optimal mix ratio is recommended as follows: 1.5%, 0.10%. Finally, three kinds parameters are predicted based back propagation (BP) neural network system. absolute value relative error between experimental less than 5%, which indicates prediction model proposed in this paper can provide a reference multiobjective optimization proportion concrete.