Direct tensile behavior of amorphous metallic fiber-reinforced cementitious composites: Effect of fiber length, fiber volume fraction, and strain rate

In this study, the effects of the fiber length, fiber volume fraction, and strain rate on amorphous metallic fiber-reinforced cementitious composites (AFRCCs) were investigated. The experimental results showed that the amorphous metallic fibers with a 30 mm length had excellent bonding performance with the matrix because of the rough fiber surface, large specific surface area, and high aspect ratio under both static and high strain rate conditions. The fibers, however, were not pulled out from the matrix and were subjected to fracture because the thin-plate shape of the fibers was vulnerable to shear force. On the other hand, the amorphous metallic fibers with a 15 mm length exhibited decreased bonding efficiency with the matrix because of the low aspect ratio and the increased number of mixed fibers, and the fibers were pulled out from the matrix. As the fiber length increased, the tensile strength, strain capacity, and tensile toughness increased because the stress dispersion effect increased alongside the increase in the internal binding force and the crosslinking reaction range inside the matrix. As for the dynamic increase factor (DIF), the amorphous metallic fibers with a 30 mm length exhibited fracture without being pulled out from the matrix. The amorphous metallic fibers with a 15 mm length, however, were pulled out from the matrix, thereby increasing the bonding efficiency of the fiber-matrix interface that is affected by the strain rate. Therefore, it was found that AFRCC-L15 had a higher DIF for the tensile strength, strain capacity, and tensile toughness.