The fracture energy of concrete reinforced with double-helix macro basalt-fibre-reinforced polymer fibre

Abstract

A novel type of fibre – double-helix macro basalt-fibre-reinforced polymer (DHM BFRP) fibre – is proposed to increase the cracking, tensile strength and ductility of concrete. The novel fibre is made from micro basalt fibres and resin, twisted together in a double helix. BFRP offers high tensile strength, good corrosion resistance and low cost, while the double-helix geometry provides excellent bond–slip performance between the fibre and the concrete matrix. Three-point bending (3PB) tests were conducted to measure the fracture energy of concrete reinforced with DHM BFRP fibres. The influences of fibre orientation (aligned and random) on cracking load, peak load, flexural strength and fracture energy were analysed. Compared with random DHM BFRP fibres, aligned fibres resulted in a 26.4% higher fracture energy and a 29.7% increase in flexural strength. Finite-element models of the 3PB tests were established using LS-Dyna. The Karagozian & Case concrete model was calibrated based on the fracture energy results to obtain a material model of fibre-reinforced concrete (FRC) considering fibre orientation. The errors between the simulated and tested maximum loads for 3PB tests of plain concrete, FRC and fibre-reinforced self-compacting concrete were 8.3%, 4.0% and 11.4%, respectively, indicating that the simulated and test results were in good agreement. This study provides a theoretical foundation and technical support for practical engineering applications of DHM BFRP fibres.