Influence of performance of multi-scale fibers on cement-based composite materials

To precisely understand the impact of multi-scale fiber on the performance of cement-based composite, a multi-scale fiber cement-based composite material was developed based on calcium carbonate whisker (CW) fiber, steel fiber, and polyvinyl alcohol (PVA) fiber. Under different multi-scale mixing ratios, various tests, including flowability test, uniaxial compression test, three point bending notch test and overlay test were conducted to study the influence of multi-scale fibers on the mechanical property, fracture performance, and fatigue performance of cement-based composite materials. The results show that multi-scale fibers have a significant impact on the mechanical and fracture properties of cement-based composites. In terms of mechanical properties, multi-scale fiber can significantly reduce the flow extension of cement-based composites and improve their axial compressive strength and flexural tensile strength. In terms of fracture behavior, both single fiber group and hybrid fiber group can improve the fracture performance of cement-based composite materials to varying degrees. Among them, the improvement law of unstable fracture toughness and cohesive toughness is relatively consistent. In terms of the improvement range of fracture performance indicators, cohesive toughness is greater than unstable fracture toughness, and the latter is greater than initiation fracture toughness. The cement-based composite materials with volume fractions of 0.50%, 0.75%, and 0.25% for CW fiber, steel fiber, and PVA fiber demonstrate relatively optimal fatigue performance. The research results can provide theoretical foundation for the engineering application of cement-based composite materials.