Multiscale insights on enhancing tensile properties of ultra-high performance cementitious composite with hybrid steel and polymeric fibers

Abstract

Ultra-high performance cementitious composite (UHPCC) is an advanced composite material with superior compressive strength. UHPCC with low steel fiber content typically fails in a single-crack mode under tension, resulting in a high risk of catastrophic structural collapse and limiting its wide application. However, high steel fiber content adversely affects the electrochemical corrosion resistance and long-term performance of UHPCC. Therefore, enhancing the tensile performance of UHPCC with low fiber content has attracted great attention. Polyvinyl alcohol (PVA) fiber is characterized by outstanding crack control ability in cementitious materials. In this study, the macroscale flowability, tensile and flexural properties, ductility and failure mode of UHPCC containing steel and PVA fibers at low fiber content level were explored and analyzed. Results indicate that the post-crack energy absorption of UHPCC improved by more than 40% following fibers hybridization. The failure mode of UHPCC with low fiber content shifted from single crack mode to ductile multiple cracks mode. Microscale observations show that PVA fibers can bridge crack and transfer load at the interface after first cracking, and impede slippage between steel fiber and matrix, thus endows UHPCC with desirable ductile multiple cracks failure mode. The findings of this study provide a foundation for designing UHPCC with ductile tensile performance and give an in-depth understanding of underlying mechanisms of hybrid fibers, promoting the application of ductile UHPCC in innovative structures.

Keywords

• Ultra-high performance cementitious composite
• Tensile performance
• Polymeric fibers
• Multiscale observations
• Underlying mechanisms