The world's largest 3D printed concrete building

Engineers from CEMEX and COBOD developed a new mix of materials to build a 190 square meter 3D printed house out of real concrete.

Real concrete 3D printed building after completion.

3D printing technology is being used with a variety of materials including steel. However, in construction, the ink used for 3D printing is always a dry mixture of mortar materials, which not only limits the scale of technology application but also increases construction costs. Mexican company CEMEX partnered with Danish 3D printing technology company Construction of Buildings on Demand (COBOD) to solve this problem.

Previous 3D-printed construction projects used a special mix to treat the slow-drying properties of plain concrete during construction. This is a major obstacle because wet concrete has a different bearing capacity than dry concrete. The solution of CEMEX and COBOD to overcome the problem is a new cement mixture called D.fab containing additives that allow concrete to be poured and accelerate the drying process of concrete. Henrik Lund-Nielsen, founder and general manager of COBOD, said the method allows for the use of locally available materials in construction.

Another advantage of D.fab is that it greatly reduces construction costs. While dry mix mortar for 3D printing costs 791 - 1,018 USD/m3, using D.fab reduces the cost to 67 - 101 USD/m3. In addition, the construction time is also significantly shortened.

The team tested the technology by building a 190 square meter house, the largest 3D printed construction out of real concrete, in the capital of Oman, Muscat. D.fab additives are obtained from Europe. The house was 3D printed in two phases. In the first stage, a team of local workers is trained in the printing process. Then they do the whole printing process themselves. The project took just 5 days to complete and the cost dropped to $1,810 compared to $22,627 if dry mix was used for 3D printing.