Influences of Specimen and Fiber Sizes on the Direct Tensile Resistance of Ultra-High-Performance Fiber-Reinforced Concretes

Ultra-high-performance fiber-reinforced concrete (UHPFRC) is a new class of concrete material that produces superior compressive strength (more than 150 MPa). In addition, UHPFRC shows significant improvements in post-cracking strength, strain capacity, and specific work to fracture based on the strain hardening behavior under tension. Thus, UHPFRC is expected as a potential material for civil infrastructure although several of its properties have not been published yet. This study aims to evaluate influences of specimen and fiber sizes on the tensile performance of UHPFRCs. Two sizes of specimen and two sizes of smooth and twisted fibers were used in the production of UHPFRCs. From the experimental test results, the tensile behavior of UHPFRC could change from strain hardening behavior to softening behavior as the specimen size increased, whereas the increase of fiber size did not alter the strain hardening behavior of UHPFRC. The tensile performance of UHPFRC was highly dependent on the fiber size and specimen size. The post-cracking strength increased, but the strain capacity significantly reduced with increasing the specimen size. On the contrary, the post-cracking strength decreased, but the strain capacity marginally enhanced with increasing the fiber sizes.