Dynamic deformation and fracture of porous cement: A high-speed X-ray phase contrast imaging study

Investigations on mechanical responses and failure mechanisms of porous cement to dynamic compression are essential for its applications as impact energy absorption material. This study conducts split Hopkinson pressure bar tests along with in situ high-speed X-ray phase contrast imaging (XPCI). Porous cements with three different porosities (4.8%, 10.4% and 18.7%) are examined at strain rates of 1800, 3600 and 5500 s −1 , respectively. The samples with higher porosity exhibits higher rate sensitivity in the investigated strain rate range, but lower peak strength at a given strain rate. A cone-shaped dynamic failure pattern of bulk cement specimens is observed through the XPCI and postmortem characterization, and crack propagating/branching/deflecting are found at the meso-scale. Quantitative analysis is carried out through digital image correlation, particle tracking velocimetry, and meso-scale finite element simulation, and reveals localized crushing bands.