Predicting Fibre Orientation and its Effect on Mechanical Properties of Ultra-High Performance Steel Fibre Reinforced Self-Compacting Concrete

Fibre orientation often plays a crucial role in the design of steel fibre reinforced self-compacting concrete (SFRSCC). Several studies highlight that fibres orient according to the SCC's flow pattern. In addition, it has been identified that fibre orientation has a significant impact on SFRSCC's mechanical properties; specifically, there exist a prevailing linear relation between the fibre orientation factor and the corresponding residual tensile strength of the material. This study extends the knowledge of fibre orientation and its influence on mechanical properties to the field of ultra-high performance steel fibre reinforced self-compacting concrete (UHPSFRSCC). For that, a UHPSFRSCC slab was cast. The slab was then cut into thirty beams that were tested in three-point bending test. An image analysis algorithm identified the number of fibres on the beam's fracture plane, enabling predicting the local fibre orientation factor. The individual results were linked to mechanical properties from the three-point bending test, composing a set of design charts that can be used for design purposes.