Improvement effect of steel fiber orientation control on mechanical performance of UHPC. (10th November 2018)

• Record Type: Journal Article
• Authors: Huang, Huanghuang; Gao, Xiaojian; Li, Linshan; Wang, Hui
• Is Part Of: Construction & building materials. Volume 188(2018)
• Page Start: 709
• Page End: 721
• Publication Date: 2018-11-10
• Subjects: Ultra-high performance concrete (UHPC) -- Flow control -- Fiber orientation -- Mechanical properties; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2018.08.146
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: One flow controlling method was developed to manufacture UHPC specimen. Fiber orientation number and coefficient in UHPC were significantly improved. Flexural strength, toughness and sMOR were increased by 64.3%, 65.1% and 77.1%. Abstract: In order to improve mechanical properties of ultra-high performance concrete (UHPC), one L-shape device with a narrow horizontal channel was developed to control the flow of fresh mixture and then the orientation of steel fibers was significantly improved. Mixtures with water-to-binder ratios of 0.20, 0.22 and 0.24 were prepared by introducing steel fibers with 1%, 2%, and 2.5% of the total volume respectively. Three fiber orientation parameters (fiber orientation angle, fiber orientation number and fiber orientation coefficient) were quantitatively evaluated by the image analysis method. Based on experimental results, mechanical properties (compressive strength, flexural strength, toughness, deflection at modulus of rupture and maximum deflection) were notably increased with the higher dosage of steel fibers. Compared with specimens prepared by a direct cast, this flow control method improved fiber orientation number and fiber orientation coefficient from 0.6 to 0.7 and 0.4–0.6 to 0.7–0.9 and 0.6–0.8 respectively. The best improvement on flexural strength, toughness, deflection at modulus of rupture and maximum deflection reached 64.3%, 65.1%, 77.1% and 14.9% respectively. Based on experimental results, linear relationships were regressed for fiber orientation parameters and mechanical properties of UHPC. Therefore, a potential method was developed to improve the reinforcement effect of steel fibers in UHPC.