Basalt/carbon-based hybrid FRP bar: Optimised design and mechanical properties

Abstract

The brittle failure mode of basalt fibre-reinforced polymer (BFRP) bar and their susceptibility to alkaline concrete environments limit their widespread application in civil engineering. To address this problem, basalt/carbon-based hybrid FRP (HFRP) bar were introduced as a new FRP material developed to enhance the reliability and safety of structural materials compared with BFRP bar. Based on the design principles of composite materials, an HFRP bar was designed using micromechanics. The fibre layout inside the HFRP bar was optimised further by a finite element analysis (FEA). The basic properties of the developed HFRP bar were measured via tensile tests. The results showed that the hybrid carbon fibre (CF) had a significant impact on the mechanical properties of the HFRP bar. The bar exhibited superior properties when the CFs were concentrated in the core. Moreover, the hybrid CFs altered the failure mode and morphology of the BFRP bar. The failure mode of the HFRP bar exhibited a plastic yield segment when the CF hybrid content (VCF) was 10 %. When VCF was 10 %, the maximum increases in the measured tensile strength and Young's modulus of the HFRP bar were approximately 13.9 % and 19.6 %, respectively, compared with the BFRP bar. When VCF was 25 %, the corresponding values were 40.3 % and 39.0 %, respectively. The maximum average difference rates of the mechanical properties of the HFRP bar obtained by micromechanics, FEA, and tensile tests were within the permissible error range. The observations of this study provide a reference for the use of hybrid fibres to enhance the mechanical properties of the conventional FRP bar and guide the production of HFRP bar.

Keywords

• Micromechanics
• Finite element analysis
• Optimise design
• Mechanical properties
• HFRP bar