US researchers develop environmentally friendly concrete for 3D printing houses
A new concrete is intended to make 3D printing houses more environmentally friendly. But this is not the only advantage over conventional concrete.
3D-printed building in Heidelberg
(Image: Werner Pluta/ heise medien)
Printing instead of building: Researchers in the USA have developed a building material that can be used to 3D print houses. The material hardens quickly, which speeds up the construction process. It is also significantly more environmentally friendly than conventional concrete, said the team from Oregon State University in Corvallis.
The basis of the material is clay. The researchers mixed this with hemp fibers, sand, and biochar. This is a charcoal-like material produced by heating wood chips and other organic materials under low-oxygen conditions. A binder based on acrylamide is also added.
Through a process called [Link auf https://de.wikipedia.org/wiki/Frontalpolymerisation%7C_blank] Frontal Polymerization, the binder begins to cure as soon as it has been printed. This not only accelerates the hardening of the building material but also allows overhangs, such as door or window lintels, to be printed.
The material hardens quickly
"The printed material has a load-bearing strength of 3 megapascals immediately after printing, which allows for the construction of multi-layered walls and free-standing overhangs such as roofs," said project leader Devin Roach. "It reaches the strength of 17 megapascals required for residential buildings made of concrete after only three days. Conventional cement-based concrete requires about 28 days for this."
Furthermore, the production of conventional concrete is very energy-intensive: it consists of water, sand or gravel, and cement as a binder. The latter is made from limestone, which is ground and then heated to over 1400 degrees Celsius.
Large amounts of carbon dioxide are released, especially in the last process step. Cement production accounts for around 8 percent of global carbon dioxide emissions. In addition, normal concrete takes significantly longer to cure.
Videos by heise
Shelters can be printed quickly
Roach sees a major advantage of clay-based concrete here: the growing world population requires rapid housing construction. Moreover, the new building material makes it possible to quickly build shelters and other structures after natural disasters.
Buildings can also be 3D printed with conventional concrete. One of the largest in Europe is a data center in Heidelberg. In Beckum, the district association of the German Red Cross (DRK) has 3D printed its administrative headquarters. The tallest 3D-printed tower to date is in Switzerland.
The team from Oregon State University describes its development in the journal Advanced Composites and Hybrid Materials. Before buildings can be constructed from the material, it must first be extensively tested by the American Society for Testing and Materials, Roach said. Furthermore, it is currently still pricier than conventional concrete. Therefore, the price must be lowered to be competitive.
(wpl)
