Flexural behavior of environmentally friendly ultra-high-performance concrete with locally available low-cost synthetic fibers

Abstract

Due to its low porosity and high particle packing density, ultra-high-performance fiber reinforced concrete (UHPFRC) is a material with superb mechanical and durability properties in comparison with conventional and fiber-reinforced concretes. The addition of fibers to the matrix allows the development of adequate behavior to direct tension and bending. However, their main back drawn is its high initial cost and its high carbon footprint. To address those issues this research aims to analyze the behavior of a previously optimized eco-friendly recycled glass ultra-high-performance concrete under flexural stress by using locally available low-cost synthetic fiber reinforcement. Besides, high-strength steel fibers were used to establish a comparison. The experimental program involved 34 dosages of UHPFRC. The results showed that, contrary to what happens with the high strength fiber, no one of the synthetic series with 1% of fiber volume fraction achieved the deflection hardening condition. However, several synthetic fibers series achieved that condition with a 2% of fiber volume fraction. Furthermore, the results also showed that the polypropylene fibers, the polypropylene/polyethylene fibers, and the hybrid combination of PVA and polypropylene/polyethylene fibers, outperformed the high strength steel fibers regarding the cost-benefit analysis for the toughness of a UHPFRC with 2% total volume fiber.