Can building a building be like printing a file? Recently, a 3D printed double-story building was topped off at the 3D printing R&D base of Three Gorges University in Yichang, Hubei.

　　"This small building is 8 meters high and covers an area of ​​100 square meters. It takes 22 days to be printed and capped from early March, and only 3 workers are needed." Li Yangbo, the technical director of the project and associate professor of the School of Water Conservancy and Environment of Sanxia University, introduced.

　　What does the machine that prints a building look like? Above the small building, there is a big white guy like a gantry - "This is a 3D building printer, and the double-story building is printed out by it." Li Yangbo said.

　　Unlike traditional brick walls, the 3D printed building walls are all made of pure concrete mortar. "As long as the parameters of the 3D printing equipment are set, the materials are stirred, and the nozzles of the printing equipment are pumped through hydraulic pressure, the house can be automatically printed with one click." Li Yangbo introduced that the walls, floors and floors of the house are all printed in an integrated manner.

　　"The key material for 3D printing houses is concrete, which needs to be both fluid and solidified." Li Yangbo said that the team debugged more than 30 materials, and finally added a certain proportion of fiber and cellulose during production to debug it into a suitable material.

　　The materials were found, and the equipment materials were difficult again. "In 2022, our first generation 3D building printer made of aluminum alloy is relatively light, and the equipment often shakes when printing," said Li Yangbo.

　　When making the second generation 3D building printer, Li Yangbo and his team replaced the main body with steel pipes, which increased the weight, but the equipment would always stutter when printing, and the accuracy would be lost again.

　　Continuous exploration and improvement, in early 2024, Li Yangbo and his team replaced the equipment structure with a gantry style, with "one leg" on both sides, and the "sole of the foot" has increased, and the "printer" has worked more stably. "Now, the deviation of the printer nozzle twice to the same position has been controlled within 0.1 mm, and the printing shape deviation does not exceed 2 mm."

　　Is there any security guaranteed? At the scene, there were many cracks on the walls of the small building. "When pouring, the temperature is around 30 degrees Celsius, and the moisture on the surface of the wall evaporates faster, resulting in cracks." Li Yangbo said that cracks only appear on non-load-bearing walls, and within a normal controllable range, it will not affect the overall structural safety.

　　In addition, the overall load-bearing of the house is a frame system composed of 15 columns and middle beams and slabs. The 3D-printed shell of the load-bearing column. "During the printing process, after the load-bearing column is printed to the height of the floor slab, weld the steel cage into it through a hollow part and weld it with the steel bars of the ground ring beam to form a whole, and then tie and install the steel bars of the second-layer slab beams into place, and cast in place for concrete." Li Yangbo said.

　　Environmental protection is another advantage. Li Yangbo introduced that 3D building printers can continue to manufacture phosphogypsum, construction solid waste, etc. generated during the construction process into raw materials. "The construction cost per square meter of this building is about 1,000 yuan."

　　A few days ago, the small building was successfully topped off. Next, Li Yangbo and his team will also conduct technical tests on the house. (Reporter Ng Jun)

[Editor in charge: Zhou Jingjie]