Evaluation of performance of hybrid fiber-reinforced self-compacting concrete using non-destructive testing techniques

The paper presents self-compacting concrete (SCC) performance at various replacements of steel fibers (ST) and polypropylene fibers (PP) using non-destructive testing (NDT). The NDT is a method of evaluating the properties of a material, component or system without causing damage. The NDT allows for evaluating the existing structures for strength and durability. The NDT performed in this research was ultrasonic pulse velocity (UPV), electrical resistivity (ER), and rebound hammer (RH), along with fresh properties and compressive strength. A total of six mixes were cast with a total of 1% fibers by volume. This 1% includes ST and PP in different proportions (0%, 0.25%, 0.5%, 0.75%, 1%) with a constant water-to-binder ratio of 0.45. The results show that the flow decreased as the percentage of fibers increased and reduced significantly when ST was 1%. The 28-day compressive strength was maximum in the hybrid mix when ST was 0.75% and PP was 0.25% compared to the control mix. ER was the minimum when ST was 1% by volume. The UPV of all SCC mixes decreased with the addition of fibers, and it was minimum when PP was 1% by volume. The 28-day RH was almost similar to compressive strength which shows the effectiveness of this test to evaluate the structures constructed with hybrid fiber-reinforced SCC. The research is significant as it evaluates the performance of hybrid fiber-reinforced SCC using non-destructive testing techniques. The results provide insight into the effects of different proportions of steel and polypropylene fibers on the flow properties and the correlation between the compressive strength and non-destructive testing parameters of SCC.