Estimating Residual Flexural Strength of Fiber-Reinforced Concrete Using the ASTM C1550 Panel Test

Abstract

Abstract The ASTM C1550, Standard Test Method for Flexural Toughness of Fiber Reinforced Concrete (Using Centrally Loaded Round Panel), round panel test has been used for quality control of fiber-reinforced shotcrete (FRS) and concrete (FRC) on numerous construction projects internationally since it was introduced in 2003. Using this method, the post-crack performance of FRS and FRC is normally expressed in terms of energy absorption. Energy absorption is useful for performance assessment in ground support applications, such as tunnel linings, because it offers the advantage of low inherent variability. However, engineers responsible for other structural applications involving FRC are usually more familiar with designs based on flexural strength rather than energy absorption. As a result, there has been a demand that post-crack performance of ASTM C1550 round panels be based on residual flexural strength. This paper describes how residual flexural strength can be calculated from data generated by the ASTM C1550 test method, and how corrections for deviations in thickness from the required 75 mm can be implemented to reduce variability in residual strength parameters and eliminate any possible bias associated with nonstandard thickness.