This experimental campaign on creep and energy absorption capacity is the first one dedicated to reinforced sprayed concrete. A new test method taking into account the specific support conditions of sprayed concrete for underground support has been designed and successfully experimented. More work is needed to assess the repeatability and reproducibility of this method.
During the experiment, six fibres and one welded wire mesh were tested. Three fibres were polymeric, three were metallic. Of course, not all the existing fibres on the market were covered and many parameters influence the results but conditions were selected to be as representative as possible of the current practise, at least in France. Still, results must not be extrapolated too quickly.
Under the level of load used during the pre-cracking phase (around 40 kN), the duration before the deflection exceeded 2 mm was of a few minutes for two out of the three polymeric fibres, whereas it was over one year for the three metallic fibres and the wire welded mesh. Results of the third polymeric fibre were intermediate (7 days; 75 days; over 1 year).
Under the load level of the creep tests (around 20 kN), no failure nor deflection above 3 mm (except for one sample) was observed.
All but one of the tested RSC maintained or improved their energy absorption capacity, even those with low pre-cracking durations or the highest creep deflection.
The contribution of reinforcements prior to the softening phase was quantitatively evaluated by calculating the ratio between Fmax of each RSC and Fmax of the non-reinforcement sprayed concrete with the same matrix. Values were notably different from one fibre to another (from +14 to +67 %) but they were not linked to the material of the fibre, either metallic or polymeric.
Acknowledgments The authors gratefully acknowledged the technical and financial supports from all the partners of this experimental programme: ASQUAPRO, ARCELORMITTAL, BASF DCCF, BEKAERT, BMS, CETU, ELASTOPLASTIC CONCRETE, NOUVETRA, SAINT GOBAIN SEVA, SIGMA BETON, SIKA, SNCF Reseau.
- 1. Larive, C., Rogat, D., Chamoley, D., Welby, N., Regnard, A.: Creep behaviour of fibre reinforced sprayed concrete. In: Proceedings of the World Tunnel Conference WTC 2015, May 22-28, Dubrovnik, Croatia
- 2. Larive, C., Rogat, D., Chamoley, D., Regnard, A., Pannetier, T., Thuaud, C.: Influence of fibres on the creep behaviour of reinforced sprayed concrete. In: Proceedings of the World Tunnel Conference WTC 2016 Congress, April 22-28, San Francisco, United States (submitted)