Properties of Powder-Based 3D Printed Geopolymers (2019-02)¶

Additive manufacturing, commonly known as three-dimensional (3D) printing is a group of emerging techniques for fabricating 3D structures directly from a digital model in a layer-wise form with less waste material. The current construction processes are labor intensive combined with a high rate of injuries [1], thus, making automation of construction processes a necessity. Development of new construction techniques such as 3D concrete printing (3DCP) opens many thresholds into the future of construction industry. Unlike the conventional approach of casting concrete into a formwork, 3DCP techniques will combine digital technology and new insights from materials technology to allow freeform construction without the use of expensive formwork. Freeform construc- tion would enhance architectural expression, where the cost of producing a structural component will be independent of the shape, providing the much-needed freedom from the rectilinear designs [1]. In the past few years, different 3DCP techniques have been explored and adopted in the construction industry [25]. One of the techniques is the extrusion-based technique, similar to the fused deposition modeling method, which extrudes cementitious material from a nozzle mounted on a gantry, crane or a 6-axes robotic arm to print a structure layer by layer. This technique has been aimed at onsite construction applications such as large-scale building components with complex geometries. The weak interlayer strength between printed layers is one of the limitations of this technology when compared with cast-in-the-mold concrete.