Effect of different sizing agent-treated basalt fibers on bending and cracking performance of reinforced BFRC beams

Basalt fiber (BF) is a green material and has been used to strengthen concrete. The mechanical properties of basalt fiber reinforced concrete (BFRC) materials and members are inconsistent in literature. Considering the influence of bonding properties between BF and cement matrix on the mechanical properties of BFRC, four scenarios of BFRC addressed with different sizing agents are included to investigate the bending performance of reinforced BFRC (100 x 120 x 1100 mm) beams through the four-point bending test. Digital image correlation (DIC) technology is adopted to measure the cracking development of the beams during loading. Based on the macroscopic results from bending test (including cracking, deformation, cracking/ultimate load, cracking/ultimate moment) and microscopic analysis by scanning electron microscope (SEM), the type of sizing agent plays an important role in determining the bonding properties at the interface between BF and cement matrix, thus affecting the bending performance of BFRC beams. Based on the cracking performance (including the number of cracks, width of cracks, and development of cracks) and ultimate load of the beams under bending load, the order from the strongest to weakest bending performance of BFRC beams with different size agent is: BFRC with dispersed basalt fibers (DBF) > flexible basalt fibers (FBF) > cluster basalt fibers (CBF) > alkali resistant fibers (ARF).