Study on the tensile and compressive mechanical properties of multi-scale fiber-reinforced concrete: Laboratory test and mesoscopic numerical simulation

To investigate the tensile and compressive mechanical properties of multi-scale polypropylene fiber-reinforced concrete (PFRC), two-dimensional microscopic finite element models of PFRC were established, and their reliability was verified using laboratory test results. The failure development process and tensile and compressive behaviors of multi-scale PFRC were simulated. In addition, the influence of the length and dosage of polypropylene fibers (PFs) on the mechanical properties of concrete was investigated using mesoscopic numerical simulations. The numerical models established in this study fill the gap in existing research by revealing both the distribution of multi-scale PFs and the true shape of the aggregates. The results predicted by the proposed numerical models were in good agreement with the experimental results. Moreover, the ideal PF length was 30 or 40 mm, and the optimum fiber dosages of two fine polypropylene fibers (FPF1, FPF2) and coarse polypropylene fiber (CPF) were 0.6 kg/m³, 0.6 kg/m³, and 4.8 kg/m³, respectively. This study reveals the influence of parameters such as the length and dosage of multi-scale PFs on the mechanical properties of concrete, providing a reference for engineering applications.