“World’s Largest Real Concrete 3D Printed Building” Goes up in Oman

COBOD’s additive construction technology has been deployed worldwide, from Germany to Kenya, the U.S. to Belgium. The latest location for the Danish firm’s construction 3D printer is Oman, where COBOD technology was used to make “the world’s largest 3D printed real concrete building.”

The key phrase there is “real concrete”, as 3D printed buildings, including those previously made with COBOD machines, typically rely on dry mix mortar formulas, not concrete. In part this is because concrete generally dries too slowly to self-support during the printing process. However, as unveiled with the first 3D printed house in Angola, a new concrete concoction called D.fab makes it possible to 3D print with real concrete and at the same, lower price.

The “world’s largest” 3D printed home made with real concrete. Image courtesy of COBOD.

D.fab was developed by COBOD and CEMEX (NYSE: CX), a Mexican multinational building materials company with $13 billion in revenue and over 41,000 employees. Because ready-to-mix dry mix mortars are five to 10 times the price of standard, ready-mix concrete, the partners sought to develop a solution that could be less expensive and created from local sand, gravel, cement.

Only one percent of the total mixture consists “magic mix” from COBOD and CEMEX. This system of admixtures consists of specialty chemicals incorporated at the batching plant that makes the concrete more fluid and pumpable. Another admixture that speeds up the curing process is added in the dosing unit at the printhead, along the concrete to gain shape. According to COBOD, this drops the cost of materials by 90 percent.

Davide Zampini, CEMEX Head of Global R&D, explained, “CEMEX has been monitoring the developments in 3D printing for some time, but it was important to intervene with a significant innovation and improvement. Although we recognize that it can be convenient to 3D print with dry mix mortar materials, our R&D focus was not to go down that route, because we believe that it is important to make 3D Printing accessible. Together with COBOD we have developed the material and technological solution for 3D printable concrete. CEMEX’s D.fab admixture range enabled the development of an innovative 3D printing approach, yet offer a material comparable to conventional concrete.”

Henrik Lund-Nielsen, Founder & General Manager of COBOD International, said of the new material, “When we began 3D construction printing back in 2017, where we 3D printed Europe’s first 3D printed building, we made the concrete recipe ourselves. We had to use a lot of cement to get it to work, with the consequence that our recipe was too expensive and not CO2 friendly. While we have been happy to help various cement and concrete manufacturers develop dry mix 3D printable mortars, we have also insisted on that a solution for making real concrete made from local available materials would be needed for mass application of our technology. We are more than pleased that CEMEX took on the challenge, and proud that we in cooperation could develop the new solution. Prices for materials will come down from the typical 700-900 Euro/m3 for3D printable mortars to now 60-90 Euro/m3 depending on geographic location. This is equivalent to a reduction in cost of materials of about 90% and is truly a game changer for our industry and the construction industry globally.”

The power of D.fab was first demonstrated with the 3D printing of a 53 m2 (570 sf) house in Luanda, the capital city of Angola, by additive construction company Power2Build. Using the material, the home cost less than €1,000 in concrete materials. This was followed by a 190 m2 (2,100 SF) home in Muscat, the capital of Oman, which relied on 99 percent locally sourced materials, aside from the D.Fab additives from Europe, which dropped the cost of the materials to under €1,600. COBOD claims that the same building with typical dry-mix mortar wold have cost over €20,000.

The Omani house was 3D printed in two stages, with the material recipe and training of the local crew performed during part one and the second stage performed by the Omani crew entirely. Altogether, the project took just five days to complete.

The home 3D printed in Oman using COBOD technology and D.fab. Image courtesy of COBOD.

While D.fab doesn’t necessarily impact the CO2 emissions associated with the production of concrete, being able to use locally sourced materials certainly lowers the carbon footprint needed for transporting construction supplies. CEMEX is working with British Petroleum in a reported effort to “decarbonize” cement production and transportation. However, CEMEX itself does not have the most outstanding environmental record, having damaged ecosystems with its sand mining operations, released the toxic chemical chromium-6 into the air around its factories, and emitted hazardous dust at its plant in Rugby, England.

What does seem to be clear is that this new additive system could make additive construction much cheaper, while automating the build process and possibly lowering costs related to labor, as well. What impact this has on the construction sector at large remains to be seen, but we do know that COBOD is quickly establishing itself as the leading manufacturer of construction 3D printers in the market so far.