Impact-Response of Tailored Composites Made of Novel Polypropylene Fibers in a Low-Clinker LC3 Matrix

The current work investigates the performance of sustainable fiber-reinforced composites (FRCs) made of limestone calcined clay (LC3) binder systems with added superabsorbent polymer (SAP). These composites were reinforced with novel bicomponent polypropylene (PP) fibers compared to standard monocomponent PP fibers. Focus is set on bicomponent PP fibers where the smooth outer surface is modified by including calcium carbonate (CaCO3) particles in the outer shell. Fibers are manufactured at IPF by a pilot melt spinning line. The dynamic single fiber pullout test is used to study the fiber/matrix interaction. The results revealed that incorporating CaCO3 particles in the outer shell significantly improved the mechanical interlocking, leading to increased energy absorption capabilities during fiber pullout compared to the smooth monocomponent PP fibers. The dynamic tensile response of LC3-based FRCs with different PP fibers was investigated using a gravitational Split-Hopkinson Tension Bar (SHTB) setup to assess the performance at high strain rates. It was evident that the bicomponent PP fibers with CaCO3 facilitated better stress transfer mechanisms in the crack flanks due to improved fiber-matrix interface, resulting in multiple crack formation with strain hardening behavior. Overall, the findings suggest that combining FR-LC3 with SAP and bicomponent PP fibers is promising for structural strengthening under dynamic loading scenarios while offering reduced carbon footprint and cost advantages.