Impact Assessment of the Mechanical Properties of High-Flowability Steel Fiber Reinforced Concrete Altered by Compaction Approaches

With the potentially oriented distribution of the steel fiber in high-flowability steel fiber reinforced concrete (SFRC), the isotropic properties of conventional SFRC have been altered by compaction approaches of fresh mix especially in the construction of pavements and overlays of roads, bridge decks, ground panels and building floors, bring a doubt of rational assessment of high-flowability SFRC by existing methods specified in codes for conventional SFRC. To clarify this issue, an experimental study was carried out for fifteen sets of high-flowability SFRC to assess the effects of three compaction approaches including the existing standard approach, the semi-imitating approach, and the highly realistic forming approach. The characteristic strength of concrete matrix was 30 MPa, 40 MPa and 50 MPa, and the mass content of ingot-mill steel fiber varied from 15 kg/m³ to 90 kg/m³. Results show that steel fibers trend to increasing distribution in horizontal from top to bottom in relevant sections of specimens with the increase of steel fiber content, which becomes more obvious in large plate specimens compacted with highly realistic forming approach. By inducing a compaction impact factor determined by different compaction approaches for high-flowability SFRC, the assessments are made on compressive strength, splitting tensile strength and flexural tensile strength, letting them more suitable for the design of plate elements. Additionally, the study evaluates the double-punching performance, the proportionality limit and residual flexural strengths of high-flowability SFRC. The findings of this study contribute to filling the gap in quantifying the impact of compaction approaches on the mechanical properties of high-flowability SFRC.