Fracture properties of basalt-fiber-reinforced bridge concrete under dynamic fatigue loading

Abstract

Basalt fibers with different lengths and contents were incorporated into concrete to improve the expansion and extension of microfractures in bridge deck concrete. A fracture performance test of basalt-fiber-reinforced bridge concrete (BFRBC) was conducted using a three-point bending loading test. A fatigue test was performed using a self-designed loading device, and load stress levels of 0.5 and 0.7 were used to investigate the deterioration trend of the fracture toughness of the BFRBC under dynamic fatigue loading. The inhibition effect of basalt fiber on concrete cracks under fatigue loading was investigated. The crack resistance mechanism of basalt fiber on concrete under fatigue loading was revealed by scanning electron microscopy using Image-Pro Plus and MATLAB software to extract relevant crack parameters. The results of the fracture performance of BFRBC showed that basalt fiber with an appropriate length and content can greatly improve the fracture performance of concrete, and 12-mm basalt fiber was adopted in concrete with a content of 0.08%. At a stress level of 0.7 after 200,000 fatigue load cycles, the deterioration of concrete without fiber content was the most significant, and the initial fracture toughness and unstable fracture toughness decreased by 22.67% and 29.28%, respectively. In addition, the crack area density, average crack width, and maximum crack length of the BFRBC decreased by 46.69%, 21.94%, and 21.35%, respectively, because of the incorporation of basalt fiber. BFRBC disperses and transmits cracks through the bridging action of fibers in its internal stresses, delaying the generation and propagation of cracks and, thus, improving the crack resistance of concrete.