A method to evaluate the formability and fluidity of concrete based materials for 3D printing

Use of 3D printers for construction brings a new possibility of creating walls with shapes that were not possible with conventional construction methods. However, existing construction materials can not be used for 3D printing as they are, and the exploration for new materials is the key to the realization of this concept. Formability and fluidity are the key factors in evaluating whether or not materials are suitable for 3D printing, including use within the field of architecture. A standardized quantitative method to evaluate construction materials is required for the comparison between materials for various projects. For example, the concrete slump test is one of the universal standards that is used to evaluate the quality and suitability for a specific construction method. In the emerging field of construction with 3D printing, however, a standardized method is yet to be established. This paper proposes an efficient method to evaluate the formability and fluidity of concrete-based materials, while only using simple instruments. The proposed method and instruments were tested by evaluating geo-polymer-based concretes, which are relatively difficult to evaluate due to its high intrinsic viscosity. By testing with these materials, we aim to show the methods ability to be applied to a wide range of materials. Notably, materials that were evaluated to be favorable under this method were confirmed to be suitable for use in 3D printing robots, being able to be used for building large structures.