Effect of embedment length on pullout behavior of amorphous steel fiber in Portland cement composites

For using amorphous steel fibers (ASF) in Portland cement composites, the performance of ASF was evaluated by a pullout test and compared to that of a hooked-end steel fiber (HSF). The embedment length of the fiber (5.0, 8.0, and 12.5 mm), compressive strength of the mortar, and number of fibers were considered the test variables. The results showed that a single ASF had a greater maximum applied load (Pmax) than a single HSF; however, at a mortar compressive strength of 30-42 MPa, its bond strength (τmax) and pullout energy (Ef) decreased by 40.9-55.8% and 16.9-79.7%, respectively, compared to those of a single HSF. Furthermore, in the pullout failure mode, the Ef of 4 ASFs, which have a volume fraction equivalent to a single HSF, was 2.10-3.04 times higher than that of a single HSF. Based on the Ef of ASFs, an embedment length of 5-8 mm is recommended to provide the most effective ASF reinforcement effect to a mortar with a compressive strength of up to 40 MPa.