Tunable mechanical behavior of auxetic cementitious cellular composites (CCCs): Experiments and simulations

This research presents an investigation of the compressive behavior of auxetic cementitious cellular composites (CCCs) using a combination of experiments and finite element (FE) simulations. Typical auxetic centrosymmetric geometry was used as unit cells for the cellular structure and fiber reinforced cementitious mortar were used as constituent material. By varying the cellular geometry, three CCCs (P0, P25 and P50) were prepared then experimentally and numerically tested under uniaxial compression with different boundary conditions. Good agreement can be found between experimental and FE simulated results: Only CCCs with chiral section (P25 and P50) exhibited auxetic behavior and a typical compressive stress–strain response with two peaks was found; Under restrained boundary condition, different from the cone confinement zone observed in bulk cementitious materials, re-entrant confinement zone was found in the auxetic CCCs. More importantly, a cracking initiated section rotation mechanism is identified for the CCCs’ auxetic behavior which is distinct from the elastic instability mechanism of polymeric auxetic materials with the same cellular structure. In terms of density, energy dissipation ability and Poisson's ratio, the auxetic CCCs shows excellent properties making them promising in various civil engineering applications.