Houses, bridges, facades - 3D technology digitizes the construction sites: Instead of using trowel and mortar, buildings are created with laptops and robots.The Frankfurter Rundschau presents five projects.Helmets and safety vests in bright fluorescent colors will probably still be on the construction site of the future.Less and less often, however, a master bricklayer with a trowel and spirit level.Instead, engineers who control robots with laptops.Future vision?No, already a reality in North Rhine-Westphalia and Bavaria.In October, in Beckum, halfway between the Ruhr area and Bielefeld, the first shell from the 3D concrete printer was created within a few days.In the Bavarian town of Wallenhausen near Ulm, an apartment building with five residential units has been printed within seven weeks since the end of October.The almost 20 meter high 3D concrete printer needed almost 24 working hours for the ground floor of the three-storey building.A team of four to five bricklayers would probably have done about a week.If the technology catches on, it has the potential to catch up to 200 years of development in the construction industry.Harald Kloft, professor at the Institute for Structural Design at the TU Braunschweig, took this view at the beginning of December at an event organized by Hessen Trade & Invest on the subject of 3D printing in construction.According to Kloft, very little has changed fundamentally in the shell construction over the past 100 to 200 years.Bricklaying or concreting crews are still about the same size as they were back then, and concrete is still poured from above into previously individually manufactured molds made of formwork.The basic features of the system formwork invented in 1912 are still used today.Kloft drew a comparison with automobile production, which is characterized by robots and a high degree of automation and can no longer be compared with the manual production at the beginning of the last century."Digitization in construction only occurs in the planning phase, it ends on the construction site," says Kloft.It is one of the worst tasks for civil engineers and architects to create 2D plans for the construction site from 3D models on the computer.The advances in productivity that the auto industry has seen have resulted in high margins and freed up funds for research and development.Not so in construction.That's why Kloft sees "great potential for increasing productivity in the construction industry" in 3D printing.In addition, completely new architectural forms are possible, which can currently only be built with great effort, i.e. uneconomically.Kloft calls this "individualized construction".He also sees great potential for greater resource efficiency, because 3D printing uses significantly less material than conventional construction techniques.For example, a lot of steel can be saved if the reinforcement is inserted directly during the concreting process - instead of first producing large self-supporting steel reinforcements that are then filled with concrete.In the Braunschweig laboratory, Kloft and his students are already experimenting with carbon as a reinforcement material or with robotically compacted rammed earth.But in contrast to the 3D buildings in Beckum and Wallenhausen, this is still a long way off, at least in practical terms.Of course, there is also the question of jobs.If only two people are needed to operate a 3D concrete printer - one controls the device, the other takes care of the material flow - that's a lot fewer than a conventional concreting crew.But: jobs that are physically very demanding, such as bricklayers, are hardly finding any new blood anyway.And: 3D printers on construction sites are designed in such a way that they do not get in the way of people on the construction site.The spray nozzles follow fixed paths on rails, so they do not move freely in space like the robotic arms that we know from car factories.Therefore, cooperation with people who carry out simple activities, such as inserting steel reinforcement in concrete, is unproblematic.In addition, according to Kloft, the new forms of production in construction also open up prospects for new skilled work profiles.A project that BASF 3D Printing Solutions is planning at the Deutsches Museum in Munich is not quite finished yet.During the ongoing renovation, an interim entrance will be created by the end of 2021.A multifunctional and translucent, three-storey high facade made of recyclable plastic is to be used there, and the BASF subsidiary founded in Heidelberg in 2017 would be responsible for the material and implementation.The façade is intended to be a spectacular design element and at the same time provide thermal insulation, as well as automatically provide shading through its wave shape and ensure ventilation with air ducts.Even electronic elements can be integrated.The planned facade could have an area of ​​600 to 700 square meters, would be 45 meters long and 15 meters high.The BASF 3D subsidiary is also cooperating with window manufacturer Okalux to integrate individually designed, 3D-printed plastic parts as slats in double-glazed windows.There they control transparency, shading and lighting.A first project is to be implemented in the first quarter of 2021."The breaks were crucial for the success of the project," says Thilo Feucht from the Institute for Steel Construction and Mechanics of Materials at the TU Darmstadt about the "AM Bridge 2019".As part of a research project, a steel bridge was printed there by two welding robots.Technically, this is not a big deal in the vertical plane, but a bridge must also span the horizontal plane.The difficulty: The liquefied metal drips down instead of attaching itself to the structure that has already been printed.The Darmstadt research team solved the problem by taking breaks - instead of a continuous welding process, a large number of individual spot welds were placed one after the other, with short breaks.This allowed the material to harden and not drip.It was actually possible to print the demonstration bridge over water from steel - the research object was, however, only about knee-high, the water spanned a ditch just under two meters wide.But the bridge carried two people at once.The MX3D company in the Netherlands has already printed an entire bridge out of steel, even there in dimensions for real use.In contrast to the research project at the TU Darmstadt, this bridge consists of individual parts that are printed in the workshop and then assembled.It passed a load test of 20 tons in 2019 and will one day span one of Amsterdam's famous canalsA 3D-printed sand sink?The start-up Sandhelden from Gersthofen near Augsburg sells this as a luxury product for more than 1300 euros.The startup also produces bathtubs, art projects, models and furniture using 3D printing.What is special about the sand material is the manufacturing process.With normal 3D printing, the printing material is sprayed in strands using a nozzle.The sand heroes have their objects printed in a bed of sand by a service provider using the binder jetting process.The rectangular pressure chamber is completely filled with quartz sand, two grains per layer are placed exactly on top of each other.In order for these to hold together in the desired shape, a binder is applied as an adhesive, then the printing blank is exposed and cleaned with air pressure.Sinks, bathtubs and other objects that come into contact with moisture are given another coating.According to the company, the grain-precise storage of the sand allows very thin and yet stable layers of 0.28 to 0.38 millimeters, depending on the grain size used and the application.Sandhelden have sold around 800 sinks since 2018.The technology allows complex shapes with an exclusive feel, customers can have their own washbasins produced in quantities of 1 using the configurator.Through a partnership, the sand heroes are represented in several hundred bathroom exhibitions.The residential building in Beckum and the apartment building in Wallenhausen were produced with a 3D concrete printer from the Peri subsidiary Cobod from Denmark.Peri GmbH from Weißenhorn near Ulm counts itself among the largest international manufacturers and suppliers of formwork and scaffolding systems.In 2019, 9,500 employees in 60 subsidiaries and 160 production sites achieved a turnover of almost 1.7 billion euros.Peri acquired a stake in the Danish company Cobod in 2018.Peri is by no means competing with itself with 3D technology, but is expanding its range and opening up new market segments, according to company spokesman Markus Woehl.Buildings constructed using 3D printers still need scaffolding for plastering and painting, for example.Relatively small buildings such as the single-family house in Beckum with 80 square meters of floor space and 160 square meters of living space or the multi-family house with 380 square meters on three floors are market segments that Peri has not previously served because they are traditionally made of brick and wood, not concrete will.With the sale and rental of the 3D printers, the company is opening up new markets, and demand is good, according to Woehl.There are many inquiries and also concrete discussions about new projects in the coming year.Everyone involved is still gaining experience with the two buildings that have now been printed, which is why Peri does not provide any information on costs and resource efficiency.In Beckum, the ground floor was printed in 50 hours within 15 days, and the first floor went much faster: 40 hours in five days.With conventional masonry technology, a similarly large shell could have been built in a similar amount of time, but not with the conspicuously rounded corners.In addition, Peri states that the printer has not yet run at maximum speed.The Chinese company Winsun 3D, founded in 2003, is a global pioneer in the use of printing technology for houses and has implemented numerous projects since 2008.In the beginning, these were rather simple objects in terms of production technology and aesthetics, made from individual parts that were assembled on site.These beginnings differ little from conventional precast concrete elements.In 2014, Winsun printed ten houses on site within 24 hours, using recycled materials and for less than $5,000 per house.A 500 meter long noise protection wall with integrated planters also came from Winsun printers.For a 1100 square meter villa, which was partly made of printed components, the savings compared to conventional construction technology are said to have been 30 percent construction time, 40 percent material and 80 percent labor costs.In the Corona year, Winsun used its technology to draw attention to itself with ten square meter isolation rooms including a washing area. Dozens of these small concrete containers were set up in China, but also in Pakistan.