In Latin America, fiber reinforced shotcrete (SRF) is widely used for tunnels linings in road, hydraulic and mining projects. In the most of these projects, the specifications commonly establish (1) the energy absorption capacity that the FRS must achieve and (2) the fiber content to be used to reinforce it. Although there are adequate standards to determine the fiber content in the fresh state and the energy absorption capacity by testing square or round panels, the criteria to evaluate compliance with the specifications given by different recommendations are based on deterministic analyzes of the test results, which do not consider the conditions of the execution of the works or a certain level of confidence, nor outlier values are identified and treated.
On the other hand, due to the random distribution of fibers in the concrete mass during mixing and spraying, the results of the fiber content tests present high scatter, provoking claims between principals and contractors.
Considering the above, in this paper a probabilistic method to evaluate compliance with the fiber content specified in a project is proposed, and expressions to determine the minimum number of fibers necessary to comply with the nominal content established in the specifications are given, which are applied to evaluate the FRS used in a real mining project developed in Chile.
