Influence of test methodology on the applicability of test results of fibre reinforced concrete for design (2020)

The design of fibre reinforced shotcrete (FRS) linings is commonly based on the Q-System or Barton charts. This performance based design approach accesses the results of experimental tests, carried out on panel specimens according to existing standards or guidelines. This is different to the general methodology to access and determine the performance of fibre reinforced concrete (FRC) using standardised beam tests.
Panel and beam test results yield significantly different information on the performance of FRC and it is problematic to correlate them. The beam test yields a stress-strain relationship for a small displacement range only. Based on the significantly different working and failure mechanisms, structural tests to evaluate the post-crack performance and the ductility of FRS linings are typically conducted on different types of panels rather than on traditional beams. As a consequence, test results based on beam tests may lead to an overestimation of FRC performance in panels and vice versa. In order to avoid uneconomic designs the most appropriate material must be found using the most appropriate test methodology.
This paper discusses the difficulty in correlating test results obtained from beams and panels as well as the discrepancy in performance of different FRC using different test methodologies and aims to provide guidance on materials, testing and design.

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