Mechanical properties and failure modes of polypropylene fiber-reinforced foamed concrete subjected to high strain rates and large compressive deformation: effects of fiber content and length

This study investigates the mechanical properties of polypropylene fiber-reinforced foamed concrete (PPFRFC) under high strain rates and large compressive deformation, focusing on the effects of varying fiber contents and lengths. Results show both peak and plateau stress increase with fiber content, reaching a maximum at 1.5 wt.% before decreasing. Similarly, increased fiber length enhances both stresses, but beyond 9 and 14 mm, they decline. The dynamic increase factor is sensitive to fiber content and length, with the lowest values observed at 1.5 wt.% content and 9 mm or 14 mm length. Failure mode analysis shows that as fiber content increases, damage extent decreases, with fewer fragments. At 1.5 and 2.0 wt.%, specimens largely retain their overall contour after impact, while fiber length has a smaller effect on failure mode.