Fiber Synergy in Fiber-Reinforced Self-Consolidating Concrete

Abstract

Self-consolidating concrete (SCC) was developed to respond to the need for concrete that can improve durability while eliminating the need for compaction and vibration work. SCC can compact itself into complicated formwork and congested structural elements under its own weight without the need for mechanical vibration. Thus, SCC decreases construction time, labor, and equipment needed on construction sites; makes the construction of heavily congested structural elements and hard-to-reach areas easier; reduces noise and injuries related to vibration work of concrete; and helps achieve higher-quality finish surfaces. Fiber reinforcement can extend the technical benefits of SCC by also providing crack bridging ability, higher toughness, and long-term durability. This article reports on a study of the potential synergistic effects in SCC incorporating different steel and synthetic polymer macro- and microfibers in various hybrid (single, binary, and ternary) combinations. The study included a total of 31 SCC mixtures, with combinations of fibers in varying proportions from 0.25 to 1.0%. The fiber length varied from 30 to 50 mm for the macrofibers, while microfibers were approximately 12 mm long. Each mixture was evaluated using the slump flow and L-Box flow tests, compressive strength tests, flexural toughness, first-crack strength in bending, and post-first-crack behavior. Results of this study show that fibers can have rheological and mechanical synergistic effects. The authors conclude that optimized fiber combinations can better increase toughness and flexural strength while maintaining adequate flow properties for fiber-reinforced SCC.