Researchers at Nanyang Technological University, Singapore have developed the ability to 3D print a prefabricated bathroom in a day. The 3D printing process cuts building times by fifty percent and the units themselves are thirty percent lighter. The technology could help companies produce inexpensive units as well as save on materials and manpower costs.
“3D printing technology allows concrete to be printed and customised. The complicated shape of a PBU and its walls can be developed and printed at a faster pace to satisfy the needs of individual customers as no formwork or moulds are required, whereas conventional construction of PBUs with concrete or lightweight wall panels always limit the possibilities of design. In addition, 3D printing can build curvilinear profiles rather than rectilinear forms,” says Er Lie Liong Tjen, team lead from Sembcorp Design and Construction, and Sembcorp Architects & Engineers.
From the Nanyang Technological University, Singapore article: "The multidisciplinary team comprising researchers across disciplines such as mechanical, civil and material engineering, architecture and robotics, had to first develop special concrete mixtures that could be 3D-printed. New mixtures include green building materials such as geopolymers, which are made from fly ash waste.
To enable printing, the team also had to develop new printing and control systems which could match the flow rate of the nozzle to the hardening properties of the concrete.
The printing was then carried out in a single build using a 6-axis KUKA Robotic arm, which has a reach of about 6 metres in diameter. The specially designed concrete mixture was fed to mixers and pumped out of a nozzle mounted on the robotic arm, depositing the material layer by layer according to the digital blueprint.
To save material and achieve weight savings of up to 30 per cent, the walls of the PBU were printed in a W-lattice shape, which lent additional strength to the final structure. "