High strain rate effect and dynamic compressive behaviour of auxetic cementitious composites

Masonry walls are known for their limited impact resistance, even when retrofitted with CFRP (carbon fibre-reinforced polymer) and nanomaterials. This paper presents the findings of an experimental study using split Hopkinson pressure bar (SHPB) tests aimed at exploring the potential application of auxetics textile reinforced mortar (TRM) composites in impact protection. This study will provide the initial understanding of the composite as a structural reinforcement solution for masonry walls. Key findings reveal that the peak strength increases with rising strain rates, highlighting significant strain rate sensitivity in TRMs with auxetic (AX) and carbon fabric (CF) reinforcements. AX samples exhibit better energy absorption as compared to the reference plain mortar (PM) samples, particularly at higher strain rates, surpassing CF samples beyond 150 s-1. Moreover, the insertion of auxetic and carbon fabrics eliminates crack development and mitigates the severity of sample failure. The negative Poison ratio effect of auxetic fabrics significantly enhances the lateral confinement, ultimately improving the dynamic performance of AX samples compared to CF samples. These findings underscore the potential of auxetic materials in enhancing dynamic performance, particularly under high strain rates, with clear implications for engineering applications, including in masonry buildings.