VIDEO: New technology can 3D print a bathroom with concealed drains and piping in less than a day

Scientists have created a system that can 3D print a bathroom -- complete with concealed drains and piping -- in less than a day. The interior of the unit includes a sink, mirror, shower, toilet bowl, ceramic tiled walls and flooring.  After printing, the bathroom is furnished with toilet fittings to become a pre-fabricated unit, ready for use in construction projects, according to researchers from Nanyang Technological University in Singapore who have developed the system.

This could potentially help firms build prefabricated bathroom units (PBU) about 30 per cent more quickly and 30 per cent lighter than current PBUs. In the past four years, the team focused on developing a special concrete mix which is fluid enough to flow through the hoses and print nozzle, yet can harden fast enough so that the next layer is able to be printed on it. 

On top of ensuring a consistent print quality, the final product also has to be as strong as conventional concrete, researchers said. The printing process takes half the time needed in the construction of a conventional bathroom unit that uses concrete casting. The fittings, tiling and finishing will typically take another five days. PBUs are usually cast from concrete and completely preassembled offsite with all necessary finishes and fittings, ready to be lifted and installed in a building project.

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By shifting most of the fabrication off-site to the controlled environment of a factory, PBUs yield time and manpower savings of about 60 per cent, compared to on-site construction which was the practice prior to 2014. There is also better control over the materials and the prefabrication process, resulting in higher quality finishes and lesser wastage. Tan Ming Jen from NTU said that 3D-printing a bathroom unit could help manufacturers halve their production time while lowering transport costs, carbon emissions and materials wastage.

"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 molds are required, whereas conventional construction of PBUs with concrete or lightweight wall panels always limit the possibilities of design," said Er Lie Liong Tjen, a team lead from Sembcorp Design and Construction in Singapore.

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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, researchers said.