Improving Mixed-Mode Fracture Properties of Concrete Reinforced with Macrosynthetic Plastic Fibers: An Experimental and Numerical Investigation

Abstract

This article offers a comprehensive analysis of the impact of MSPF on concrete’s mechanical properties and fracture behavior. Combining findings from numerical simulations and laboratory experiments, our study validates numerical models against diverse fiber percentages and aggregate distributions, affirming their reliability. Key findings reveal that mixed-mode fracture scenarios in fiber-reinforced concrete are significantly influenced by the mode mixity parameter (Me), quantifying the balance between mode I and mode II fracture components, ranging from 1 (pure mode I) to 0 (pure mode II). The introduction of the effective stress intensity factor (Keff) provides a profound understanding of the material’s response to mixed-mode fracture. Our research demonstrates that as Me approaches zero, indicating shear deformation dominance, the concrete’s resistance to mixed-mode fracture decreases. Crucially, the addition of MSPF considerably enhances mixed-mode fracture toughness, especially when Me ranges between 0.5 and 0.9, resulting in an approximately 400% increase in fracture toughness. However, beyond a specific threshold (approximately 4% FVF), diminishing returns occur due to reduced fiber–cement mortar bonding forces. We recommend an optimal fiber content of around 4% by weight of the total concrete mixture to avoid material distribution disruption and strength reduction. The practical implications of these findings suggest improved design strategies for more resilient infrastructure, particularly in earthquake-resistant constructions and sustainable urban development. These insights provide a valuable framework for future research and development in concrete technology.