Facilitating Ductile Failure of 3D Printed Concrete Elements in Fire (2020-07)¶

This research investigates 3D printed concrete behaviour at elevated temperatures. Preliminary studies indicate that delamination of filament layers occurs at elevated temperatures, as opposed to thermo-hygral spalling, which typically occurs in conventionally cast high-performance concrete samples. Brittle structural failure may therefore occur during a fire scenario since little to no reinforcement is currently included in the 3DCP process. This research proposes the incorporation of steel fibres into the additive manufacturing process to facilitate ductile failure and increase interlayer mechanical properties. The fibres are vertically aligned, orthogonal to the printing plane, and strategically positioned to bridge multiple filament layers. 3D printed rectangular samples are heated via radiant gas panels and thereafter tested in four-point bending once they have cooled down to ambient temperature to determine post-fire flexural capacity and ductility properties. This study shows that steel fibre inclusion improves the structural fire performance of 3D printed elements by 33% and provides post-peak mechanical ductility to yield deflection softening. More research is required to ultimately develop a standardized economical structural fire design process for 3DCP.