Experimental study on dynamic mechanical properties and enhancement mechanisms of iron ore tailings foam concrete reinforced with different fiber types

This study examines the effects and underlying mechanisms of polypropylene fiber (PF), glass fiber (GF), and basalt fiber (BF) on the dynamic mechanical properties of iron ore tailings foam concrete (ITFC) when incorporated individually. Through scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray computed tomography (X-CT), and the split Hopkinson pressure bar (SHPB) tests, the research systematically evaluates how different fiber types influence the matrix characteristics, pore structures, and dynamic mechanical behavior of ITFC. The results reveal that the main causes for the difference in the dynamic mechanical properties of the specimens containing solely BF (CBF), PF (CPF) and GF (CGF) stem from three factors: the intrinsic mechanical properties of the fibers themselves, the influence of fiber incorporation on the matrix hydration process, and the effect of fiber incorporation on the pore structure. CBF demonstrates superior mechanical performance at low strain rates owing to the properties of BF. However, the presence of extremely large pores within CBF results in relatively low strain rate sensitivity. While both CPF and CGF exhibit lower early strength, CGF achieves the highest DIF in both strength and energy dissipation density due to its low porosity and dense matrix. In contrast, CPF demonstrates higher strain rate sensitivity in energy dissipation density because of the high elongation of PF.