Marcus Ehrenberger, Strabag: "If the construction sector does not move towards sustainability, we will have a big problem"

Given that Europe has only 9% of the necessary raw materials, sustainability is an essential condition for the construction sector, argue the specialists of the Strabag company who work in the Zublin Innovation Center in Stuttgart, Germany and who are looking for the best solutions in this regard and for for that company to become neutral in terms of carbon emissions by 2040. Especially since according to the information provided by Strabag representatives, the construction industry is responsible for 38% of the greenhouse gases emitted on the globe, it is a large consumer of energy - approximately 35% and generates more than 35% of industrial waste in the European Union. Moreover, 80% of ores and 50% of raw materials are used by the construction industry.

Dr. Marcus Ehrenberger, Senior Function Lead Sustainability Management Environment&Energy stated, during a presentation he gave at the center in Stuttgart: "First of all we have to build ecologically and therefore it is necessary to determine what kind of materials prime we will use in the next period. Then it is about constructions, about how much steel we should use or if we can make buildings that are lighter but as safe as those that contain steel, and finally we have to analyze the efficiency of sustainable, durable constructions. At the heart of the construction industry, we need to put the idea of a circular economy, to take care of the resources we need and reuse them when possible. Regarding construction sites, we need efficient, environmentally friendly buildings, both on the logistics side and on the management side. (...) Achieving sustainability in construction is a marathon, not a sprint, which we must complete by 2040, with everyone's effort. If the construction sector does not move towards sustainability, we will have a big problem, due to the lack of the necessary materials - most of them are in countries with authoritarian or non-democratic political regimes - and their price".

The head of the sustainability team at Strabag also told us that digitization can be an important factor and can be the key to making prefabricated materials with less raw materials that are needed at the moment.

Marcus Ehrenberger said: "The most important challenge for our company is to refurbish, to rebuild the existing buildings. Through this we aim to reduce carbon emissions and reduce climate change. We are not naive, we know that we will face new climate changes, the question is how much they will impact us, and therefore it is our responsibility that the buildings built for clients respond to these needs and reduce the effect of these changes. The steel industry is responsible for 10% of carbon emissions, half of which comes from steel used for construction. Cement manufacturing is responsible for 8% of gas emissions; one-third of these are caused by burning limestone in clinkers, grinding and transportation, and two-thirds are caused by chemical reactions during cement production. That is why new technologies and innovative materials are needed, such as the replacement of Portland cement, sustainability data and the implementation of a circular economy, through reuse, remanufacturing, repair, recycling and recovery of prefabs and other primary materials. Even the use of efficient innovative materials, which means a lower amount of materials than currently used. Especially since this is a requirement of the company's clients, who are interested in the carbon footprint that the property they want has on the environment. We are here to use new concepts, to develop new materials, new constructions and to draw new targets to constantly monitor in the coming period. We are basically talking about a real management of sustainability in construction that we try to implement in every project".

• HVO fuel and recycled asphalt, two technologies implemented by Strabag

Thus, in order to reduce CO2 emissions, the experts from the Innovation Center of the Strabag Zublin company have implemented two innovative solutions and are working on the third one. The first concerns the use of hydrogenated vegetable oil (HVO) as fuel for vehicles used on construction sites, which is a diesel-like fuel produced by processing vegetable and animal oils and fats, such as waste fat. It is suitable in any blend or as a pure fuel in approved diesel engines and allows a maximum 90% reduction in CO2 emissions. The HVO project was launched in January 2024, when the construction sites where the new fuel was to be used were selected, as well as the suppliers of the respective oils, in February it was determined which construction equipment and machines are compatible with HVO, and in June they were already used on the Strabag construction sites over one million liters of HVO fuel.

The second solution implemented by the specialists from Strabag-Zublin is the recycling of asphalt, by using a recuperator that allows heating the material without the use of a flame, avoiding damage to the bitumen. This technology can only be used for 50% of the asphalt required for a job, but Strabag experts claim that it is technically possible to use higher proportions of recycled asphalt (between 70% and 100%) depending on the job performed. Moreover, at the level of the Strabag group, its own asphalt requirements are also covered by the use of this technology, which has optimized the asphalt production process. For example, last year Strabag used 1.3 million tonnes of recycled asphalt in works carried out in Austria, Germany and Poland.

Regarding the use of recycled asphalt, Marcus Ehrenberger stated that it is used in the functions of the construction regulations in each country or each local administration and he opined that at the European level there should be a uniform regulation, for all member states, regarding the standards in construction and the use of new technologies, in order not to leave room for arbitrariness in the preparation of documentation in public procurement procedures for large infrastructure works.

We note that the Zublin Innovation Center in Stuttgart, a six-story building, was realized by the Strabag group with an emphasis on sustainability in all phases of design, construction and operation. The structural work was completed using a low carbon concrete from the floor slab to the roof. The aluminum in the window frames and the post and beam structure of the facade has a high recycling content of up to 70% and is fully recyclable. The whole project is an example of how modern construction can be environmentally friendly, with a reduced use of materials.

The third solution is the creation of an urban construction and technology center in which the construction material waste resulting from urban works will be relocated and encapsulated, which will be recycled and used on other construction sites. Such a center will be built by Strabag in the port area of Bremen and will have the effect of reducing waste, the number of truck transports and CO2 emissions.

Marcus Ehrenberger stated: "We will recycle concrete from old buildings, from demolished buildings, and we will make a new type of concrete, with less CO2 emissions. The recycling of construction materials is the important part of this project, and that is why we chose to build it near the city of Bremen, because we consider the city as an urban mine, from whose old buildings, under renovation or demolition, we can extract the necessary materials for new constructions. Practically, during the operation of the center, all the buildings of the city are potential sources of recyclable raw materials for our company, but also for other companies that will want to use the technology of that center".

He also said that the Bremen project is still under analysis by Strabag's decision-makers, that it needs permits from German local and regional institutions, and that construction of the center will actually begin in 2 or 3 years.