Comparing Different Procedures for Calculating Flexural Cracking Toughness Using Edge-Notched Disc Bend Specimen Under Modes I and III

This research used 30%, 40%, 50%, and 60% coarse aggregates and 0.15%, 0.3%, and 0.45% wavy steel fibers to make end-notched disc bend self-compacting concrete specimens for calculating and comparing flexural cracking toughness index by ASTM C1609, JSCE SF-4, and JG/T 472-2015 methods under pure modes I and III. The variation trends of different procedures under pure mode I was more affected by coarse aggregates and fibers had no noticeable influence. But under pure mode III increasing both fibers and aggregates improved the flexural cracking toughness. The estimation of JG/T 472-2015 method was better than other methods under pure mode I. In pure mode III, due to positive effect of fibers on the pre-peak, peak, and post-peak areas, the deflection exceeds 1 mm. Hence, calculating the area under the load-displacement curve is facilitated for the ASTM C1609 and JSCE SF-4 methods up to L/150 deflections.