Fiber alignment and its effect on mechanical properties of UHPC: An overview. (16th August 2021)

• Record Type: Journal Article
• Authors: Huang, Huanghuang; Gao, Xiaojian; Teng, Le
• Is Part Of: Construction & building materials. Volume 296(2021)
• Publication Date: 2021-08-16
• Subjects: Fiber alignment -- Functional properties -- Mechanical properties -- Structural applications -- UHPC; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.123741
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Better fiber alignment is achieved by optimizing mixture flows and electromagnetic field. Image analysis and CT scan can be used to quantitatively evaluate fiber alignment. Fiber alignment can enhance dynamic and quasi-static mechanical properties of UHPC. Fiber alignment can reduce electrical resistance and improve self-sensing of UHPC. Abstract: Ultra-high performance concrete (UHPC) is attracting increasing interests worldwide due to its excellent mechanical properties and durability. Securing fiber alignment corresponding to the direction of principal tensile stress can greatly enhance the mechanical performance, especially flexural and tensile properties of UHPC. In this paper, an overview on fiber alignment and its effect on mechanical properties of UHPC is presented. The changes in flow patterns of mixture and the assistance of electromagnetic field during casting can lead to a higher improvement in fiber orientation (up to 80%) compared to other fiber alignment methods. Quasi-static flexural strength, toughness, and tensile strength can be enhanced by 10%-80%, 20%-100%, and 30%-90%, respectively, for UHPC with fiber alignment compared to those with random fiber orientation. This can enable up to 2% reduction in fiber volume needed to secure a similar mechanical performance. Such fiber alignment can increase the dynamic compressive strength and flexural strength by up to 20% and 50%, respectively. Moreover, fiber alignment can lead to the reduction of electrical resistance and improvement of self-sensing ability of UHPC due to the formation of a more complete conductive network. To promote the research and application of fiber alignment in UHPC, the alignment of flexible fibers that can bend in mixtures and the alignment of fibers in mixtures containing coarse aggregates where fiber alignment can be interfered should be further investigated. Furthermore, practical applications of fiber alignment in UHPC structural elements should be advanced.