Doo Yeol Yoo

TL;DR: In this paper, the early-age strength development and mechanical properties of hardened UHPFRC were reviewed, and the effects of the curing conditions, coarse aggregate, mineral admixtures, fiber properties, specimen size, and strain-rate on the mechanical performance of UHP FRC were specifically investigated.

TL;DR: In this paper, the authors investigated the mechanical properties of ultra high performance fiber reinforced cementitious composites (UHPFRCC) with four different fiber volume fractions within an identical mortar matrix.

Abstract: For investigating the effect of fiber content on the material and interfacial bond properties of ultra high performance fiber reinforced concrete (UHPFRC), four different volume ratios of micro steel fibers (Vf = 1%, 2%, 3%, and 4%) were used within an identical mortar matrix. Test results showed that 3% steel fiber by volume yielded the best performance in terms of compressive strength, elastic modulus, shrinkage behavior, and interfacial bond strength. These parameters improved as the fiber content was increased up to 3 vol.%. Flexural behaviors such as flexural strength, deflection, and crack mouth opening displacement at peak load had pseudo-linear relationships with the fiber content. Through inverse analysis, it was shown that fracture parameters including cohesive stress and fracture energy are significantly influenced by the fiber content: higher cohesive stress and fracture energy were achieved with higher fiber content. The analytical models for the ascending branch of bond stress-slip response suggested in the literature were considered for UHPFRC, and appropriate parameters were derived from the present test data.

TL;DR: In this article, 10 large ultra-high-performance concrete (UHPC) beams reinforced with steel rebars were fabricated and tested, and the experimental parameters included reinforcement ratio and steel fiber type.

TL;DR: In this article, the effect of fiber length and placement method on the flexural behavior, tension-softening curve, and fiber distribution characteristics of ultra-high-performance fiber-reinforced concrete (UHPFRC) was investigated.