Influence of basalt fibre on cracking behaviour and flexural toughness of concrete under the coupled effect of fatigue load and hydrodynamic pressure

The coupling effect of fatigue loads and hydrodynamic pressure has a considerable impact on the durability of pavement concrete. For moderating crack development and improving toughness, basalt fibres (BF) are applied in pavement concrete. The main purpose of this study is to evaluate the performance of using BF in inhibiting cracks and enhancing the toughness of concrete under various coupling conditions. The three-point flexure toughness of basalt fibres-reinforced concretes subjected to the coupled effect of fatigue load and hydrodynamic pressure were carried out, and the strain field of concrete during the bending test was recorded by the digital image correlation (DIC) technique. The cracking behaviours (fractal dimension, tortuosity, surface roughness) during coupling actions and bending tests were characterised by 3D laser instrument and X-ray computed tomography. The experimental results showed that stress level played a decisive role in the deterioration degree of pavement, as stress level increased from 0.5 to 0.7, the bending loads corresponding to the turning point of Df decreased. The hydrodynamic pressure accelerated crack propagation of concrete, especially when loading cycles exceeded 100,000. The addition of BF changed the micro-crack development model of concrete and significantly increased the fracture energy of concrete under coupling actions.