Pull-out creep of hooked-end fibre embedded in ultra-high-performance concrete

If the beneficial effects of fibre reinforcement are to be considered in design of ultra-high performance fibre reinforced concrete (UHPC) structure, an understanding of the long-term creep behaviour is essential. The flexural/ tensile properties of UHPC depend on the individual contribution of discrete fibres that control the overall tensile properties. The creep of UHPC therefore depends on the pull-out creep of individual fibres under sustained load. Very little research has been conducted on single steel fibre pull-out creep. To address this lack of understanding, the impacts of fibre embedment length, fibre embedment angle and sustained load on pull-out creep are investigated in this research. The outcomes of the research show that for hooked-end fibres, a change of embedment length does not significantly influence pull-out creep. The inclination angle (angle be-tween loading axis and fibre-embedded axis) had a significant role in concrete breakage at the loading end (embedded end at loading side) which generally occurred during the application of sustained load. Therefore, the pull-out creep was influenced by the fibre inclination angle for concrete breakage during application of sustained load. Finally, as expected with an increase in load, fibre pull-out creep increased.