ABSTRACT
The paper presents the results of quasi-static and dynamic experimental investigation to examine the tension, compression, and fracture behavior in an ultra-high-performance concrete (UHPC) composition, with the inclusion of steel fibers. The quasi-static experiments were performed on planar Brazilian disc geometry for split tensile strength and cubic geometry for compression. In addition, a center-notched circular disc was used for fracture toughness experiments. Dynamic tensile experiments were conducted using split Hopkinson pressure bar apparatus. The UHPC samples with a varying number of days of curing showed increased strength under quasi-static loading. It was seen that the steel fibers enhanced the strength of UHPC, dominating the peak as well as post-peak strength and behavior. All the properties measured in this work without ultrafine constituents to UHPC showed similar values, and thus may not be required in the presence of fibers. Further, in-situ imaging and digital image correlation calculation showed the onset of a single primary crack in tension, compression, and fracture failure, with fiber bridging leading to higher tensile strength.
