Mechanical Properties of Structures 3D-Printed With Cementitious Powders

Abstract

The three dimensional (3D) printing technology has undergone rapid development in the last few years and it is now possible to print engineering structures. This paper presents a study of the mechanical behavior of 3D printed structures using cementitious powder. Microscopic observation reveals that the 3D printed products have a layered orthotropic microstructure, in which each layer consists of parallel strips. Compression and flexural tests were conducted to determine the mechanical properties and failure characteristics of such materials. The test results confirmed that the 3D printed structures are laminated with apparent orthotropy. Based on the experimental results, a stress-strain relationship and a failure criterion based on the maximum stress criterion for orthotropic materials are proposed for the structures of 3D printed material. Finally, a finite element analysis was conducted for a 3Dprinted shell structure, which shows that the printing direction has a significant influence on the load bearing capacity of the structure. maximum stress criterion; anisotropic structure.3 layers are printed one atop another, a complete 3D object is constructed.Currently, the 3DP technique can print products using powder materials such as sand, plaster, cement, metal, and ceramic [13][14][15]. It is thus suitable to use liquid-particle mixed cementitious materials, such as cementitious concrete composed of cement and aggregate, to produce civil engineering projects.The application of 3DP in engineering manufacture may shorten the development cycle, reduce the production cost, and improve productivity. When applied to civil engineering, it has the potential of reducing the number of site workers, speeding up the construction process, and reducing risks during construction. A 3DP model can also be very conveniently linked to a building information model (BIM) [16], making the whole process from design, construction, management, maintenance and even decommission digital.The last few years have experienced rapid development of 3D printers. More and more materials can now be used in 3DP processes. The size of 3D printers has also increased rapidly, making it likely that in the near future it would be possible to build large and complex-shaped structures by printing. In 2010, Italian inventor Dini developed a large 3D printer named D-shape [17], which made it possible to print buildings of irregular shape. Dini is currently cooperating with Dutch architect Ruijssenaars to print a Mobius strip-like building. The construction using D-shape is four times as fast as the traditional means, and costs just one half as much as traditional construction. Novikov and colleagues, architects at the Institute for Advanced Architecture of Catalonia in Spain, invented a robot named Stone Spray which can use organic materials as the base material in 2012 [18]. This robot constructs architectural shapes by depositing a mix of soil and eco-friendly binder with the help of a jet spray system. Professor Khoshnevis at the University of Southern ...

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