Experimental study on dynamic compressive properties of cement-iron ore tailings foam composites with various polypropylene fiber parameters

Polypropylene fibers (PPFs) have been widely used in composite materials due to their sound crack resistance and toughness. In cement-based composites, the incorporation of PPFs can significantly improve their dynamic mechanical properties. However, cement-iron ore tailings foam composite (CIFC), a sustainable material utilizing iron ore tailings to partially replace cement, has not been investigated under dynamic loading. This study investigates the dynamic compressive behavior of CIFC with 1%–2.5% PPF content and 3–12 mm PPF lengths under various strain rates. The microstructural characteristics were analyzed prior to dynamic testing. X-ray diffraction (XRD) identified crystalline phases including CaCO3, Fe2O3, SiO2, C-S-H gel, and ettringite. Scanning electron microscopy (SEM) observations demonstrated that appropriate PPF parameters (e.g., C2L9, a CIFC specimen containing 2% PPF with 9 mm length) enhance fiber-matrix bonding and minimize interconnected pores and microcracks, revealing pronounced fiber bridging effects. Split Hopkinson pressure bar (SHPB) tests were then conducted at strain rates of 120–250 s−1, showing that the dynamic properties of CIFC were highly dependent on both strain rates and PPF parameters. Compared to other specimens, C2L9 exhibited a more intact failure pattern with superior compressive strength and energy dissipation capacity, despite showing reduced dynamic increase factor (DIF) and normalized energy dissipation (NED) values. These findings provide practical guidance for applying CIFC with varying PPF parameters in impact-resistant structural designs.