Steel fibers with non-circular cross-section used as reinforcement in self-compacting concrete

Abstract

The paper evaluates the methods of consideration of a non-circular shape of the cross-section of a steel fiber in determination of the aspect ratio of the fiber as well as the influence of these fibers on mechanical properties of the matrix. The analysis has been performed on the example of a composite made from self-compacting concrete and two types and three volume ratios (0.5%, 1.0% and 1.5%) of steel fibers with rectangular and part-of-a-circle cross-sections. Compressive and flexural tests have been performed. The influence of the above mentioned steel fibers on the mechanical properties of SCC has been analyzed in the view of the latest investigations performed on cement-based materials reinforced with fibers with non-circular cross-sections. Based on the research it is found that the compressive strength is slightly affected by the fibers. The flexural behavior of the SCC reinforced with non-circular fibers is comparable to that with the circular ones only in case of long corrugated fibers. In case of these fibers pronounced improvement of the flexural parameters has been observed proportional to the amount of fibers. The influence of short hooked fibers on the flexural behavior of SCC is less predictable and also different from the one observed for circular fibers. It has been shown that the differences in definition of the aspect ratio of the fiber without consideration of its cross-sectional shape can lead to underestimation of the aspect ratio. The real aspect ratio was used in the formula to describe the flexural tensile strength of SFR-SCC, however, it seems not to be crucial as other factors are unknown.