Effect of vibration time on steel fibre distribution and flexural behaviours of steel fibre reinforced concrete with different flowability

The present study aimed to evaluate the effect of vibration time on steel fibre distribution and flexural behaviours of steel fibre reinforced concrete (SFRC) with different flowability, three different vibration times (i.e., 10 s, 30 s and 60 s) were selected to compact SFRC specimens on the vibration table in this study. The flowability of SFRC was represented by the varying slump from 80 mm to 200 mm. The flexural performance tests were conducted on beam specimens under four-point loading. The steel fibres distributed on the cut section of the specimen were counted, and the distribution rate of steel fibre in each layer was statistically analysed. The results showed that a correlation existed between the vibration time and the flowability of SFRC. Increasing the vibration time led to a downward settlement of steel fibres to the bottom layer of specimens and segregation of the concrete matrix of high-flowing SFRC. This resulted in a reduction of flexural strength, toughness and fracture energy. An optimal vibration time should be determined corresponding with the flowability of SFRC to achieve a better flexural performance.