Compressive Characteristics of Perforated Re-entrant Auxetic Steel Honeycomb–Mortar Composite

Abstract

The possibility of achieving auxetic behaviour in conventional mate-rials is currently attracting significant research interests in the form of auxe-tically-enhanced cementitious composites and, especially, in re-entrant honey-comb structures. Most studies on the behaviour of re-entrant steel honeycomb auxetic reinforcement for concrete focus on achieving uni-planar auxetic behav-iour perpendicular to the direction of loading. This study focuses on investigating multi-planar auxetic behaviour throughout the composite. The auxetic behaviour was achieved by perforating the steel sheets before making the re-entrant honey-comb structures. The re-entrant honeycomb was fabricated by folding mild steel strips 70 mm-wide into a re-entrant profile and welding the strips onto one an-other. Three types of perforations were investigated, representing three categories of samples: circular perforation, orthogonal elliptic perforations, and orthogonal peanut perforations. The perforated samples were compared to the non-perfo-rated re-entrant honeycomb (control) through compression strength tests of the composites. Direct tension tests were also carried out on each steel strip in order to understand their respective stress-strain behaviour. The study demonstrates that perforating the re-entrant honeycomb walls could be a simple method for achieving multiplanar auxetic behaviour in re-entrant steel honeycomb rein-forced cementitious composites. Keywords: Auxetic, Cementitious composites, Re-entrant honeycombs.