Around 220 million tons of mineral construction waste accumulate in Germany every year, which is more than half of the total waste generated. The largest share is made up of soil and stones from excavated soil, dredged material and railway ballast. The remaining approximately 90 million tons are made up of construction rubble, bitumen mixtures from road demolition, gypsum building materials and construction site waste. Around 90 percent of all mineral construction waste is recycled, especially in landfill construction or for backfilling excavations in opencast mines. In a Europe-wide comparison, Germany is doing well. But is that enough?
There are a lot of resources in the construction waste made of concrete, bricks and tiles alone. The materials were once manufactured with a lot of energy and CO₂ emissions. After buildings and infrastructure have been converted, they are primarily processed into bulk materials for road and earthworks. This is not the often used term downcycling, because here recycled materials are used as a replacement for natural gravel or gravel – the materials meet the same requirements as primary raw materials. However, recycled building materials only replace 13 percent of the primary mineral raw materials in construction.
In order to get more recycled material onto construction sites, the Replacement Building Materials Ordinance (EBV) was introduced around a year ago, on August 1, 2023. It regulates the installation of mineral replacement building materials in technical structures, such as roads, bridges and railways. This initially created a nationwide requirement for the utilization of mineral waste as substitute building materials. The materials must now be tested more strictly for the possibility of recycling. Limit values for pollutants are also set.
Some construction waste now has to be transported over long distances for disposal
Recycling and construction companies complain that the new regulations are having the opposite effect. In a survey by four construction and recycling associations, only five percent of the 156 companies surveyed said that more construction waste and excavated soil would be recycled since the introduction of the EBV. 52 percent saw no change – and 42 percent of companies said that less material was being processed for reuse than before.
“The EBV is missing the crucial component,” says Felix Pakleppa, managing director of the Central Association of the German Construction Industry (ZDB), which represents medium-sized construction companies. “The so-called End of Waste Ordinance is missing.” They should have clarified under what circumstances mineral substitute building materials are given product status so that they can be used more flexibly locally. “Contrary to what was expected, this regulation did not come about, and now we have the absurd situation that everything that is excavated or demolished is considered waste and, in accordance with the EBV, is subject to new limit values, new measuring methods and more effort. “”
For example, in road construction, the asphalt rubble used to be used directly as filler material in the lower layer of the new road section. The paver took the broken material at the front and at the back it came out of the machine chopped into small pieces as new building material. Today you first have to sample, analyze and document the pieces of asphalt. This can be done on the construction site, but there is often not enough space for temporary storage and time to wait for the results of the tests.
In the survey, many construction companies complain about the great uncertainty in implementing the requirements of the EBV in practice. For example, the acceptance conditions for processing plants have changed. Reality shows that high costs, limited capacities and complex requirements make legally compliant recycling difficult. This leads to tense situations, especially in federal states with high construction activity and limited landfill capacities, such as Bavaria. In some cases, construction waste has to be transported over long distances for disposal, for example to Thuringia. According to the ZDB, clear regulations and practical recycling methods are necessary in order to comply with legal requirements and to strengthen the circular economy.
According to the survey, the demand for mineral recycled materials has also fallen, as many builders – including authorities – prefer primary building materials. “It's just easier to select standardized materials such as 'grain size 0/32 for road construction' in the allocation mask, and that's it,” explains Pakleppa. As a replacement for additional building materials, extensive documentation about EBV compliance must now be created with complex evidence of quality monitoring and application testing. It would be easier if recycled materials were assigned to clearly defined grades or product categories. “But we are still missing this system of product classes,” complains Pakleppa.
Even states and municipalities often do not want to build with substitute building materials
The companies point out in the survey that the term “waste” also deters many clients, even though the recycled building materials are just as good as new. In many cases, states and municipalities also do not want to build with substitute building materials. “I can understand that,” says Pakleppa. “Which mayor wants to build a kindergarten on garbage and then have to justify it to the parents?” Nevertheless, states and municipalities have a role model function and they have to justify building with substitute building materials, he demands.
“If we do not bring the material flows into product status, we will not use them on a broad scale in a way that is comparable to building materials,” says Johannes Kreißig, Managing Director of the German Sustainable Building Council (DGNB). Of course, the aim is not to turn all construction waste into products. It's about risk assessment.
Kreissig points out the usefulness of the regulation with regard to soil and water protection. “We don’t want to bury materials somewhere in the landscape or in infrastructure that we don’t know what’s actually in them, and then have to deal with pollutants in the soil and groundwater years later.” On the one hand. On the other hand, it wouldn't be possible to regulate everything completely and exclude all risks, otherwise “we won't be able to build any more.”
The cycle path on the Spree opposite the main train station in Berlin shows the absurd dead ends that rigid regulations can lead to. When it was built, diesel residues from passing excursion steamers were found in the samples of the excavated soil. In addition, the material was not allowed to be reinstalled. Instead, it was dumped in a landfill and replaced with fresh soil. But of course the steamers continue to operate in the same way as before the construction work, with the result that the new ground is also contaminated with diesel. Absolutely nothing was won here.
However, when houses are demolished, demolition waste contains not only concrete, bricks and tiles, but also adhesives, sealing foam and insulation materials, often inextricably linked to one another. Older buildings may also contain hazardous substances, such as asbestos. It goes without saying that such non-uniform mixtures cannot be easily returned to the material cycle.
“I think the problem is a little further ahead,” says Johannes Kreißig. It's not about a higher recycling rate, but rather about smaller amounts of building materials – at least in building construction. In the future, there will be less demolition and more existing buildings to reuse. And use the materials as pure as possible and with detachable connections, is his conclusion.
“It’s a real shame that we don’t address the issue of substitute building materials in a positive way,” concludes Felix Pakleppa from ZDB. “Our companies want to build with them.” And I believe that many architects and builders also value the sustainable use of building materials.” But with the current regulations, that hardly works.
