3D Printing of Concrete (2018-04)¶

3D printing of concrete has emerged as an exciting additive manufacturing topic that has brought together experts from Architecture, Engineering, Manufacturing, and Construction industry to develop materials, technologies, and systems needed for practical applications. While 3D printing of concrete is not expected to replace conventional site cast or prefabricated construction just yet, the many advantages of this technology makes it uniquely qualified for immediate applications where conventional Reinforced Concrete (R/C) would not be feasible. This is particularly the case of the development of future space habitats. This paper discusses a recent effort conducted at Penn State University that resulted in building a 3D printing machine consisting of a robot arm and pump-driven printer, to develop 3D printable mixtures with materials indigenous to Mars. The paper describes the research efforts undertaken to print: (1) a truncated cone to evaluate the slump property, (2) a cylinder to determine compressive strength, and (3) a beam to determine flexural strength. The paper also addresses challenges in the design of the toolpath for proper printing, considering rheological aspects of the mixture. Finally, the paper discusses design issues and challenges regarding the use of fibers, including proper length in relation to nozzle diameter, flexibility in relation to matrix, and bonding between layers.