Material Characterization of Diversity Aggregated Cementitious Materials Produced with a Modular Lightweight Additive Manufacturing Extrusion System

Applications of additive manufacturing in the construction industry started three decades ago with the first patent and prototype of the contour crafting process. Since then, its obvious benefits in reducing labor cost, construction waste while improving efficiency and flexibility have led to the development of several large-scale commercial machines in this field. However, proper lab-scale machines for training experts in automated construction and research-based activities such as material optimizations for civil and structural engineers are not available. The only available small-scale apparatus in AM-based construction is limited to a minimal list of materials and properties. Those machines are not capable of fabricating samples from cementitious materials with a variety of aggregate sizes. This paper compares two low-cost, modular AM-based construction systems capable of extruding a wide variety of cementitious materials with diverse aggregate sizes. The systems are capable of controlled extrusion with a variety of cross-section forms. The system can be attached to a robotic arm, CNC machine, or other programmable machines. As a proof-of-concept, the developed system is utilized to fabricate cement mortar with larger aggregate sizes with different materials mixture ratios. Mechanical performance of the resulting additively manufactured cementitious parts is examined and compared.