Cement-fibre composites for additive building manufacturing

The fused deposition principal of additive manufacturing (AM) involves the deposition of a material one layer at a time allowing the creation of an object from a 3D digital design. The associated reduction in the amount of waste material produced offers benefits and over the last decade, investigations have been carried out using cementitious materials for AM within the construction industry. Central to the profile of the technology increasing within the industry is the development of a suitable cementitious material which may be deposited without formwork. Research currently consists of ground-based gantry, or robotic arm methods which can be single or multi-agent. This paper presents the development of fibrous cementitious mortars and pastes suitable
for a miniaturised deposition system designed for use in a multi-agent AM approach. Synthetic polyvinyl alcohol (PVA), aramid and kevlar fibres along with natural fibres from the banana plant were investigated to evaluate contributions to the workability, buildability, mechanical strength and failure mechanisms of the cementitious composite material. The addition of fibres to a cementitious matrix results in compressive and flexural strength increases and transforms the method of failure from brittle to ductile. Results suggest PVA and kevlar fibres are suitable for a composite cementitious material with optimised rheology specifically designed for a multi-agent, miniaturised deposition approach for AM.