Flexural behavior of HPFRCC: Enhancing post-crack strength and toughness by magnetic alignment of the reinforcement

This paper presents an investigation on the effect of magnetic orientation of steel fibers on the physical-mechanical and electrical properties of a High Performance Fiber Reinforced Cement Composite. A simplified magnetic circuit was proposed to align the reinforcement within the cementitious matrix. X-ray Computer Tomography was employed to qualitatively access the fiber distribution in hardened specimens. Physical and electrical properties were characterized by ultrasound propagation velocity and electrical resistivity, while mechanical performance was evaluated by flexural and compressive tests. Scanning electron microscopy was used to study the damage processes in the fiber-matrix interfaces. Results showed that the magnetic circuit designed in this study was able to generate a preferential orientation of the steel fibers, increasing the ultrasound propagation velocity and causing anisotropy in the electrical properties. Furthermore, the modulus of rupture and toughness of the composite were significantly enhanced, leading to a feasible reduction in the critical fiber volume for bending when fibers are aligned. (C) 2020 Elsevier Ltd. All rights reserved.