ABSTRACT

Fiber-reinforced concrete composites find many special applications where the toughness enhancements are of great value. The composite properties of hybrid fiber additions in a high-strength concrete matrix are highlighted in the present study. The performance characteristics of different fiber combinations in concrete were assessed as to the compressive, flexural, and toughness properties. Concrete mix was designed based on the packing density obtained from the binary and ternary packing of aggregate and binder content. A slag-based binder was used as a partial replacement for cement. Hybrid fibers consisting of polypropylene (PP) and steel fibers were added at different dosage levels for varying the fiber lengths to study the fiber synergy in a high-strength cement matrix. The experimental test results indicated that the hybrid steel fiber additions in concrete (60-mm long and 35-mm short fibers) exhibited a highest compressive (45.7 MPa) and flexural strength (7.20 MPa) compared to steel monofibers additions. Synergistic fiber performance was also observed in hybrid steel fiber combination (60-mm long and 35-mm short fibers) which demonstrated a good post-crack toughness properties. In addition, the hybrid fiber composite consisting of longer PP and steel fiber combinations exhibited a highest toughness value around 117.70 Nm. The test results evidently showed that the influence of hybrid fibers consisting of long fiber combinations demonstrated improved pre-peak and post-peak load-deflection characteristics of concrete.