Enhanced energy absorption of auxetic cementitious composites with polyurethane foam layers for building protection application

Abstract

Cementitious composites with impact energy absorption capabilities can have wide applications in protective structures. This paper presents an experimental investigation on the flexural response and energy absorption of auxetic cementitious composites reinforced with polyurethane foam. In total, ninety (90) composite specimens were prepared from polymer cement mortar overlayed with either carbon fibre fabric or auxetic fabric and polyurethane foam insertions in the upper and lower regions. These specimens were tested under flexural loads using a four-point loading setup at varying loading speeds from 1 mm/min to 300 mm/min. Digital image correlation method was employed to study the failure modes, displacement profiles, load-displacement curves, and energy absorption characteristics. The auxetic fabric overlayed composites exhibited increased energy absorption and ductility without any signs of debonding compared to the commonly used carbon fibre overlayed composite specimens. Polyurethane foam insertions in the upper part of the composites prevented splitting of the specimen by reducing the crack widening in the compression zone of the cementitious matrix. Additionally, an increase in loading rate improved the energy absorption capacity of the auxetic fabric cementitious composites compared to carbon fibre cementitious composites. Findings from this study will have applications for protecting structures that are vulnerable to impacts.