Impact Performance of Low-Fiber Content HPFRCC: From Material to Structural Behavior

It has been typically observed that concrete structures have a brittle failure mode by shear or punching under high-loading rates. The small capacity for energy absorption of plain concrete is responsible of such brittle failure development upon diagonal crack formation. High-performance fiber-reinforced cement composites (HPFRCCs) have superior performance than plain concrete in tension, not only by the higher tensile strength but especially regarding the energy absorption capacity associated to multiple cracking and crack-bridging ability. In order to understand the possible benefits of using HPFRCC under impact loading in structural applications, research must be done at both material and structural level. The present contribution deals with an experimental study on HPFRCC specimens subjected to impact. Reference quasi-static tests have been also carried out. The HPFRCC mix was reinforced with 1.6% volumetric amount of short straight high-strength steel fibers. The study at material level has focused on prismatic specimens subjected to pure bending, which allows to analyze the flexural strength and specific energy absorption capacity. Structural tests have consisted of beams reinforced with conventional longitudinal steel bars without stirrups, thereby assigning the resistance of the webs against shear to the contribution of the fibers. The results are presented in comparison with companion specimens of conventional plain concrete, which has allowed showing the higher strength, ductility and energy absorption capacity achieved with the utilization of the properties of the HPFRCC under both quasi-static and impact loading conditions.