Assessment of mechanical response and damage mechanisms in fly ash and basalt fiber beams strengthened with different FRP wrap configurations

Abstract

Abstract Sustainable materials and effective strengthening methods can contribute to the significant improvement of the structural performance and durability of reinforced concrete (RC) beams. 40% cement-fly ash replacement offers better sustainability and workability, whereas fibre reinforcement and external fibre reinforced polymer (FRP) wrapping are able to offer better strength and ductility. This paper is an experimental study where thirteen RC beams were studied, one of them being a conventional control beam, basalt fibre reinforced beam (BFRB) fibre contents of 0.5%, 1%, 1.5%, 2% and beams strengthened by applying E-glass fibre reinforced polymer (EGFRP) wraps, and glass fibre reinforced polymer (GFRP) wraps at 50, 75, 100, and 150 mm. In all mixes of concrete, fly ash was used as a partial replacement of cement (12.5%). The beams were tested to assess the load–deflection response, stiffness, ductility, cracking and failure modes. The mid-span deflections were determined analytically and the deflection was determined by the double integration method, which was compared to the experimental results. Basalt fibre content was found to result in much higher load-carrying capacity, stiffness, ductility and crack control than in the control beam, and a 1.5% of basalt fibre gave the best balance between strength and deformation capacity. A higher fibre dosage of 2.0% resulted in reduced performance due to fibre agglomeration. External FRP wrapping further improved beam performance, with closer wrapping spacings (50 and 75 mm) offering superior confinement and crack-bridging effects. GFRP wrapping consistently outperformed EGFRP, and the GFRP-wrapped beam with 1.5% basalt fibre and 100 mm spacing achieved the highest load capacity and deflection. As a whole, the obtained results showed that the concrete beams can be reinforced with the observed load conditions by applying the combination of fly ash, basalt fibres and external FRP wrapping.

The authors' abstract, as published at the source. Journal of Engineering and Applied Science, 2026 · DOI ↗