Evaluation of Steel Fiber-Reinforced Sprayed Concrete by Energy Absorption Tests

摘要

Steel fiber-reinforced sprayed concrete (SFRSC) is widely used for ground support in underground works. The panel test, as in EN 14488-5, is one of the most common procedures for the quality control of the energy absorption capacity of SFRSC. The test entails the use of large equipment to manipulate and characterize heavy specimens that cannot be easily extracted from a structure in case a direct assessment of the material in place is needed. Alternative procedures, such as the Barcelona test (BCN), have been used to assess the energy absorption of cast fiber-reinforced concrete in smaller-scale cylindrical specimens that can be extracted from a structure and are considerably less demanding in terms of equipment and payload. The objective of this study is to evaluate the use of the BCN as a substitution of the traditional square panel test to assess the energy absorption of SFRSC. Both tests were conducted in parallel in combination with the quantification of the incorporated fiber content through an inductive test. Hence, the analysis reflects the actual control conditions of the SFRSC under the influence of spraying. Results indicate a possible reliable correlation between the BCN and panel test if the cracked area is considered. Different sizes of cores were tested to understand the influence of this parameter in energy absorption by the BCN test. The reduction of specimen size demands an increase in the number of determinations per batch to ensure representative results. The study suggests that the BCN can be considered a viable method of evaluating the energy absorption of SFRSC in cores extracted from test panels or actual tunnel linings.