A Novel Lightweight Mechanism for 3D Printing of Cementitious Materials (2023-04)¶

Applications of additive manufacturing (AM) in the construction industry started 3 decades ago with the first patent and prototype of the contour crafting process. Since then, its obvious benefits in reducing labor cost and 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 often costly and require large spaces. The only available small-scale apparatus in AM-based construction is usually limited to being able to print only a minimal list of materials with fine sizes. As a result, 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. Additionally, the systems can be attached to a robotic arm, or other computer numerical control (CNC) machines. As a proof-of-concept, the developed system is utilized to fabricate cement mortar with larger aggregate sizes with varied material compositions. Mechanical performance and shrinkage of the resulting additively manufactured cementitious parts are examined and compared.