Crack Width Estimation in Steel Fibre Reinforced Concrete (SFRC): Design and Limitations

The estimation of crack widths in steel fibre reinforced concrete (SFRC) with and without conventional reinforcement is still relatively uncharted territory. Engineers are faced with many challenges and uncertainties when designing SFRC members, such as precast SFRC tunnel segments, steel fibre sprayed concrete tunnel linings and other underground structures, owing to the peculiarities associated with SFRC behaviour, particularly when it is used without conventional reinforcement. At present, Eurocode 2 focuses on the design conventional reinforced concrete, as such, its recommended methodology for crack control is not applicable to SFRC. However, other guidance documents, such as fib MC2010, Concrete Society TR63, RILEM TC 162-TDF σε method, DafStb Guideline and research works by Johnson et al., are available and provide some recommendations with respect to crack width estimation in SFRC with and without conventional reinforcement. This paper reviews the aforementioned methods and evaluates their peculiarities, assumptions and differences with regards to the calculation of crack widths in SFRC.