Effects of Steel Fibers on Mode III Fracture Energy in Self-Compacting Concrete

Abstract

In this research, using the Bažant size effect law and applying cylindrical circumferential notched specimens, the mode III fracture energy of the steel fiber reinforced self-compacting concrete (SFRSCC) is calculated. It has been observed that, although the addition of 0.3 (v%) of steel fibers made the concrete splitting tension record a twofold increase, the mode III fracture energy witnessed a reduction of about 46% as well as the compressive strength, which experienced a decrease of less than a quarter. Also, it was noticed that there was a clear size effect for the mode III fracture of self-consolidating concrete (SCC) and SFRSCC, which pronounces for larger specimens. Furthermore, the addition of fibers declined the rate of characteristic stress reduction and the impact of the size effect was reduced. The brittleness number remained almost constant for different mixes containing fibers, albeit it demonstrated higher values as the specimen size grew. In addition, an approximate normalized relation estimating the mode III fracture energy of fiber-reinforced SCC in terms of normalized compressive strength and splitting tension is presented. The results showed that addition of steel fibers not only did not improve the mode III fracture energy of concrete but it reduced. Moreover, the mode III fracture energy takes lower values for SCC compared with conventional concrete.