Development and modeling of a bendable UHPC using pure steel fiber reinforcement

Abstract

Cementitious composites with high compressive strength usually have low toughness, and vice versa – it’s difficult to achieve high strength and high toughness simultaneously. In this investigation, an ultra-high-performance concrete (ASFHT-UHPC), featured with both ultra-high strength and high toughness, is prepared using aligned steel fiber reinforcement and examined through four-point bending tests. The results show that when the volume fraction of high aspect ratio steel fibers is 0.6 % or above, the ASFHT-UHPC specimen is “bendable” – its ultimate deflection to span ratio is up to 0.03, which is almost 20 times that of conventional UHPC. A model of the bending behavior of the ASFHT-UHPC beam is proposed, in which the interaction between the steel fiber and matrix, and the influence of the volume fraction, aspect ratio, and orientation of the steel fiber were taken into account. Both the modeled and test results show that the volume fraction, aspect ratio, and orientation of steel fibers are crucial for the toughness of the UHPC beam specimens. Also, good agreement is achieved between the model and experimental tests, and the model can be used to predict the bending properties of the ASFHT-UHPC beams precisely. The steel fiber reinforced high-toughness UHPC combines the advantages of ECC (engineered cementitious composites) and UHPC, which is helpful for the improvement of the safety and resilience of structures.