3D Printing

3D printing is a revolutionary technology expected to bring radical changes in the productive industries. From plastic objects and metal aircraft parts to food and human organs, 3D printing is experiencing rapid growth over the last decades, with continuously expanding scope. In the building industry, 3D printing can bring unprecedented changes as it combines great benefits. The high degree of digitization and automation allows:

  • Design versatility – The construction of complicated structures with high curvature is feasible.
  • Construction speed – Construction time is reduced at least by half, a fact that is confirmed by pilot and commercial applications.
  • Reduced waste – Material disposal due to poor design or failure is virtually eliminated, thus improving the environmental footprint of the construction.
  • Improved labor costs – The manufacturing speed of 3D printing will allow the same amount of human resources to be employed in a larger number of projects.

The present 3D printing technology is employed in building construction applications, mainly on a laboratory level or in buildings of small dimensions under sheltered conditions, using gantry type or articulated systems, which face the following challenges:

  • Gantry types require a time-consuming installation and consist of large and bulky pieces that are difficult to transport and store. In the case of portable systems, there is a significant limitation on the stability of the printing unit.
  • The existence of stationary gantry bases leads to the use of bridge cranes which may result in reduction of construction height or very high costs due to the use of actuators such as telescopic hydraulic cylinders and secondary systems.
  • Modular systems act as cantilevers meaning that their cost increases along with the requirement for support. Costs can be offset by reducing the extent of the printer, causing complications or a reduction in printing capabilities.

It is therefore clear that the existing 3D-printing technology is still at an “embryonic” stage with great room for improvement, especially in terms of printing capability, stability and portability. The primary goal of this project is to develop an innovative 3D printing system with the following key concepts:

  • Ability to implement the construction of large-scale and diverse buildings (large workplaces) – as expressed by the modern trends in architecture.
  • Cost reduction through innovative design and avoidance of dependencies on secondary systems. In existing printers, the active element that deposits the mortar is attached to the body of the device, resulting in cost increase proportional to the size of the structure. It is proposed to separate the 3D-builder into two fundamental parts (support system and print-head) that will be easily installed and will harmonically operate for a wide range of construction dimensions.
  • Cost optimization, time and accuracy of printing the building. The cost of building can be affected by two key factors: construction time and human resources needs. Existing large-scale technologies require either the need for a high-level operator training or the automation system’s conditional programming. It is herein suggested the implementation of Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) technologies in line with the operating principles of modern CNC. The design of the building will be carried out using commercial 3D CAD software and the system will automatically start building the construction through CAM. This automation will lead to a rapid increase of the speed and accuracy of the construction due to the limitation of the human factor.
  • Easy maintenance, storage, transport, installation of the layout. Typical layouts are mainly large-scale, with significant installation and transport requirements. Gantry type machines require many installation tasks including the fitting and, above all, the alignment of the bulky tracks on which the device’s body moves. It is herein proposed the use of folding machine support in order to achieve small volumes in the shrunk condition as well as the absence of moving parts.
  • Ability to use the layout in a wide variety of topographical and meteorological conditions. These objectives are indicated by the reality of island and continental Greece, where both the approach and the placement of such systems can be proved difficult or impossible. Additionally, the ability to use the system in a variety of weather conditions will be examined in order to determine possible use under rain, wind, etc. The adaptability of the system in a variety of weather conditions is of major importance, as the system must be able to maintain its stiffness and kinematic accuracy regardless of conditions, ensuring high manufacturing accuracy.
  • Achieving high strength and satisfying the anti-seismic safety standards, especially for the Greek region. Printed specimens will be subjected to an assessment of their static strength and dynamic behavior against seismic vibrations of known characteristics. The new building material will be designed to have a consistent structural behavior equivalent to or better than conventional concrete.

Expected Results

Upon the completion of the project, it is expected that an innovative 3D printer will be offered for building constructions with the usage of special cement mortars or special types of concrete.  The results include:

  • Design and development of 3D-printer using cementitious material
  • Design and application of special cement paste or special concrete types for 3D printing