–  It is already clear to some companies that traditional concrete sales will be difficult in just a few years' time. The big players are influencing the entire industry. There is a clear will among the country's cement and concrete producers, developers and building owners to move forward and reduce their carbon footprint. This is crucial for a real transition, says Jan Suchorzewski, unit manager for material design at RISE. 

Alternative binders and the reuse of concrete elements are expected to be part of the solution in the future. 

–  There are a number of pieces to the puzzle that need to be put in place for reusing concrete to work in the marketplace, including technical safety in processes where we lack a standard in Sweden and the EU for ensuring the quality of reused concrete elements. There are methods developed in RISE research projects, but no current requirements. In addition, we need a link between demand and supply, i.e. a market place where we collect recycled building products for sale, explains Jan Suchorzewski. 

There is a big difference between reusing products such as windows, doors, toilet seats and other construction-related products compared to load-bearing structures such as concrete frames in terms of requirements and safety. 

– To ensure the quality of the material and its properties, such as strength, fire safety, sound insulation and so on, much more information and data is needed. But there is a lot of interest in both the construction and concrete industries. There are now several large-scale examples of successful projects from ambitious players, says Jan Suchorzewski. 

Research with concrete results

A high-profile project has been carried out in Gothenburg, where RISE has been commissioned by NCC to reuse 3,000 square meters of hollow concrete slabs from the now-demolished Ikea store in Kållered. The hollow core slabs will now be part of a new housing development in another part of Gothenburg. This is after RISE has verified and tested the strength and life expectancy of the old concrete. 

– When you have experience in this kind of mission, it goes pretty fast. That's also why we believe in standardizing to reuse. At Ikea, one of the things we did was research the technical documentation from when the store was built and compare it to the actual material. We re-examined the concrete and tested its compressive strength. It turned out that the concrete was of the same quality as when it was freshly produced and had the potential to last twice as long in the new buildings. That was fantastic, says Jan Suchorzewski. 

A standard for recycled concrete is in the development stage. Hopefully as early as 2025. Jan Suchorzewski is a member of the Precast Concrete Committee at SIS, the Swedish Standards Institute. 

– We have started work on the development of a standard and quality assurance system for reusable precast concrete products. There is a draft of the standard and we will be inviting the stakeholders in the industry to discuss it as early as the end of 2024. The hope is that a consultation will be sent out next year. The standard will be in place by the end of 2025, he says.  

Alternative binders

An important part of concrete's future potential is recycling and reuse. Another is developing alternative binders to cement to make new concrete. Katarina Malaga, professor of sustainable construction with a doctorate in the chemical and mechanical degradation of stone and concrete, explains how this might be possible. 

– Cement can be mixed with fly ash or slag. This is called climate-friendly concrete. However, there are technical requirements that limit the amount of alternative materials that can be used in concrete in order to have a quality guarantee. RISE is also working to develop and verify new alternative materials that have the potential to replace fly ash and slag, which are becoming less available as the power and steel industries transition. There are applications where we need to use a cement that will give us a robust and durable concrete structure that will last over 100 years, such as bridges and other infrastructure, she says.

Research, development and collaboration are the way forward

According to the two concrete experts: It's important to research and develop relevant, quality-assured solutions together with the industry.

One example is Betcrete 3.0, led by RISE with funding from Vinnova. This initiative brings together the entire value chain for the cement and concrete industry in a broad stakeholder collaboration. Another initiative is Återhus - building houses from houses, coordinated by RISE. 14 parties are involved, including Akademiska Hus, Heidelberg Materials, NCC, the City of Stockholm, Tyresö Municipality, Svensk Betong and others.

– Within Återhus we have, for example, the Lindome area development, which is managed by Förbo. The work includes the replacement of existing buildings with new ones. Here we will make an inventory of the buildings to be demolished and get a concrete picture of the current situation in terms of which load-bearing parts can be reused, says Jan Suchorzewski. This type of practical example will be useful for the entire industry, where we are pooling knowledge and experience.  

Making innovations a reality

RISE has broad and deep expertise in concrete and cement. RISE has supported the Swedish concrete and construction industry with research, development, testing and education since the 1940s. The Nordic region's first large-scale test and demo environment for 3D printing of concrete was inaugurated in the spring of 2024. 

– We provide an open platform for collaboration, development and learning. This accelerates innovation and ensures that things go from idea to reality. We can build prototypes, test them at full scale, and also develop everything from the material to the finished product, says Jan Suchorzewski.

Both he and Katarina Malaga are positive about the future and, above all, about the willingness of the various players in the industry, large and small, to embrace change. 

– Many in the industry understand that climate concrete and circularity are the future if they want to survive, they conclude. 

See RISE expertise in concrete

The construction and real estate sector is responsible for about one fifth of Sweden's climate impact. Over a 20-year period, the sector will gradually reduce its greenhouse gas emissions to 25% by 2030 and net zero by 2045. At the same time, housing construction is expected to increase.

A "paradigm shift" that challenges all stakeholders 

To succeed in this seemingly impossible equation, the industry needs to get better at recycling the most climate-intensive materials.

"In many ways, this is a paradigm shift that requires coordination, a shared vision and pragmatism from all stakeholders," says Andreas Johansson, Marketing Manager at RISE, who is working on the issue.

So far, reuse in the construction sector has largely been limited to small parts such as windows and doors.  

"A lot of work is being done, but the carbon footprint is only a few percent of the total potential."

To have a real impact on the carbon footprint of the construction industry, it is therefore necessary to systematically reuse heavier building components, such as load-bearing structures made of wood, steel or concrete. The technology is there, the know-how is there, and there is a growing willingness to address the issue. But ingrained patterns point in a different direction.  

"The demolition process is not designed for reuse, but for landfill. Valuable structures are then easily crushed to make them easier to transport. Procedures are also being developed to ensure that reused parts are not damaged and meet current requirements."

It is also difficult for an architect working on a new building to reuse heavier components without knowing what is available.

"If you don't know what you can work with, you won't think about reusing building components to the extent necessary."

Common digital infrastructure for accessible building components 

The solution is a common digital and physical infrastructure:  

• A searchable database - a place to store the data of available building elements for reuse. This data includes not only what is available, but also the location, price and quality of the components. 
• Reuse depots - giant 'warehouses' where building elements are stored awaiting appropriate reuse. 

"To create such a digital infrastructure solution, and to start with larger intermediate storage facilities for heavier building elements, we need common images and visions," says Andreas Johansson. "We believe that we should look at this as an infrastructure project and that the public sector is needed to make it happen. Parallels can be drawn with other infrastructure such as roads, power grids and waste management."

Large interim storage facilities for reusing building components 

One challenge to getting started is the size of the proposed interim storage facilities. For example, a demolition project such as Snäckan 8 - a large office and commercial building in the centre of Stockholm - would require a temporary storage facility of around 60,000 square metres.  

"The smaller depots that exist today, for example for the reuse of windows and doors, are far from being able to handle this volume."

In order to get things moving, it is therefore necessary not only to get industry and municipalities on board, but also to promote the use of reused building components. Mr Johansson cites the example of adjusting municipal land allocations to make it easier to use recycled materials.

"Industry and the construction sector want to reduce their carbon footprint. Cities want to do the same. At RISE, we are therefore holding joint discussions with actors who can take the lead and get the first recycling depots up and running.

This is a large and complex undertaking in its infancy. But the potential is great, says Andreas Johansson, who sees several future implications of increased reuse of heavy construction elements.

"Around 14 million tonnes of construction waste is generated today. This is about three times as much as Sweden's total household waste. The biggest impact on the sector's carbon footprint will come if we can start reusing concrete frames and steel girders."

"At RISE, we want to help ensure that the work in progress contributes to the whole. If you are a responsible person in a construction company or municipality and would like to contribute or find out more, please contact us."