The influence of steel fibre properties on the shrinkage of ultra-high performance fibre reinforced concrete

•Investigates influence of a range of fibre types on drying and autogenous shrinkage.•Addition of any fibre type leads to a reduction in shrinkage.•Increasing fibre volume decreases shrinkage.•Hooked end fibres and fibres with highest aspect ratio reduce shrinkage more.•Blending of fibres leads to a marginal improvement in behaviour. In this study, the effects of fibre volume fraction, fibre type, and aspect ratio on various shrinkages of the ultra-high performance fibre reinforced concretes (UHPFRCs) were experimentally investigated. Single fibre pull-out tests were conducted and the corresponding results were incorporated to explore the underlying mechanism governing the magnitudes of both autogenous and drying shrinkages. In general, the presence of randomly distributed steel fibres was found to reduce both the total and autogenous shrinkage, and more specifically, an increase in fibre volume fraction or fibre aspect ratio results in significant mitigation in both total and autogenous shrinkages. Hook-end fibres were found to be more effective in restraining autogenous shrinkage compared to straight fibres and consequently blended fibre mixes that include straight fibres were less effective at restraining shrinkage than only hooked-end fibres.