The flexural strength and fracture toughness of reactive powder concrete in response to changing fibre size and pre-setting pressure

In this study, steel fibre mixtures having different compositions of fibres with various sizes were used in reactive powder concrete. The mixture composition, which would present the best performance during the flexural tests, was determined. Pre-setting pressure tests at six different magnitudes (0, 5, 10, 15, 20, 25 MPa) were conducted on the freshly prepared reactive powder concrete mixture having the determined mixture composition. The 30-mm-long steel fibres mixed at a ratio of 4.5% provided the highest flexure strength and the fracture toughness during these tests. The highest pre-setting pressure was attained at 25 MPa and the flexural strength of the sample increased by 117% reaching 28.07 MPa at that pre-setting pressure.