The effects of impact loading on the mechanical properties of the SFRCs

The mechanical properties of steel fiber concretes (SFRCs) exposed to impact loading were investigated within the scope of this study. For this purpose, three different steel fibers having aspect ratios of 45, 65, and 80 were used in 0.5%, 1.0% and 1.5% volumes, respectively in order to provide 10 different concrete mixtures. Compressive strength of these concrete mixtures was almost 50 MPa. Cylindrical specimens having 150 mm diameter and 300 mm height were prepared. These specimens were cured in water for 28 days. After curing, the specimens were cut in 150 mm diameter and 50 mm height dimensions for impact test. Impact tests were conducted on these specimens by dropping weights on the cylinders, and their impact fracture energies were determined. Another group of concrete specimens which were produced from the same concretes and which were 150 mm in diameter and 50 mm in height were exposed to impact loads of 25%, 40% and 55% of their impact fracture energies in order to identify the mechanical losses in terms of their compressive strengths and splitting tensile strengths following the effect of the impact.As a result of this study, it was found that the loss of mechanical properties in SFRCs exposed to impact loads significantly decreased compared to non-fibrous concretes. Steel fibers partially absorbed the effect of the impact, and diminished the rupturing effect of the impact on the concrete by distributing the impact throughout the specimen.

► The SFRCs displayed a much higher resistance against the impact loading effect than the plain concrete (PC).
► The fiber aspect ratios and the fiber volumes had significant effect on the impact fracture resistivity of the SFRCs.
► The loss of mechanical properties in SFRCs exposed to impact loads significantly decreased compared to PCs.