Investigating the Crack Velocity in Ultra-High-Performance Fiber-Reinforced Concrete at High Strain Rates

Abstract

The initiation and propagation of crack in the ultra-high-performance fiber-reinforced concrete (UHPFRCs) subjected to static and high speed loading was investigated. A pre-notched three-point bending specimen was installed in a Universal Test Machine (UTM) and in an Improved—strain energy frame impact machine (I-SEFIM) to investigate the crack propagation in UHPFRCs at static and highs train rates. The failure process of specimen during the test was capture by a high-speed camera system, while edge detection algorithms (EDAs) and digital image correlation (DIC) technique were used to analyze the initiation and propagation of the crack. The crack velocity in the UHPFRCs was strong influenced by the applied strain rates: the crack velocity increased as the applied strain rate increased. In addition, the fiber reinforcement significantly slowed down the crack velocity in the UHPFRCs at both static and high strain rates.