Correlations in Performance of Fiber-Reinforced Concrete Assessed Using EN 14651 and Modified ASTM C1609/C1609M-19 Beam Tests

The mechanical performance of fiber-reinforced concrete (FRC) is commonly assessed using simply-supported beam-based test methods such as ASTM C1609/C1609M-19, Standard Test Method for Flexural Toughness of Fiber-Reinforced Concrete (Using Beam with Third-Point Loading), and EN 14651, Test Method for Metallic Fibre Concrete - Measuring the Flexural Tensile Strength (Limit of Proportionality (LOP), Residual). These methods can be used to characterize flexural performance at first peak and in the post-crack range for specimens of FRC prepared either in the laboratory or in the field. The EN 14651 test method involves application of a central point load to a notched beam, with performance quantified as flexural strength expressed as a function of crack mouth opening displacement. The ASTM C1609/C1609M-19 test method involves application of third-point loading to a beam lacking a notch, with performance quantified as load resistance expressed as a function of central deflection. The distribution of stress differs between the two test methods, and it is difficult to directly compare post-crack performance. However, a method of calculating the crack width for a third-point loaded beam based on the measured central deflection and crack offset from the center of loading has recently been published. This method permits the post-crack performance of an ASTM C1609/C1609M-19 beam to be expressed in terms of the estimated maximum crack width without directly measuring the crack width. The current investigation examines whether post-crack flexural strengths obtained with ASTM C1609/C1609M-19 using this modified method produces equivalent performance to that obtained using EN 14651 for a given FRC mixture.