Testing the future of near-zero cement

In the small community of Älvkarleby in northern Uppland, you not only find beautiful nature and a well-known waterfall but also one of Sweden's oldest hydroelectric power plants. It is also here that Vattenfall has its laboratory where research is conducted on everything from biodiversity and smart electrification to how to develop materials with the lowest possible carbon footprint.

The laboratory has existed for over 80 years, initially focusing mainly on safety in hydroelectric power plants and dams. Since the late 1980s, the business has developed, and the site now houses its concrete lab built for research purposes.

Erik Nordström, Per-Erik Thorsell, and Bojan Stojanovic, work at Vattenfall's research and development center in Älvkarleby. On the dock behind them, there are samples of concrete in the water, that are being tested to see how they react over time.

Initially, the research was conducted solely for internal use, but today they also perform external concrete testing. Concrete used in major infrastructure projects in Sweden have all been tested in this lab.

The laboratory provides many advantages and is a significant strength for Vattenfall as a company, notes Erik Nordström, a specialist in dam and hydraulic construction and an adjunct professor in concrete construction at KTH.

"Our operations have long been a model for creating a lab with high-quality, knowledgeable staff and consequently, research where the results can be trusted. In hydraulic construction, we focus a lot on maintaining our facilities so they last as long as possible. Therefore, we need to understand durability, how to make status assessments, and how to repair the constructions, among other aspects."

Cement, steel, and seabed

Vattenfall Research & Development's main target is questions about material selection and how Vattenfall can radically reduce carbon dioxide emissions in its operations. For a long time, the primary research concerned cement and issues like footprint, strength, and longevity, but five years ago, they also began testing steel.

Steel is of interest to Vattenfall due to the large towers for offshore wind power, that are driven into the seabed. A few years ago, they also launched a geotechnical lab due to the growing interest in investigating seabed material for offshore wind power.

"The strength of having our lab is that we have the knowledge within Vattenfall instead of solely relying on consultants. We want to be skilled clients, which requires knowledge", explains Per-Erik Thorsell, section chief and head of the material laboratory in Älvkarleby.

Vattenfall Research and Development is right by the river in Älvkarleby.

Around 120 employees work within Vattenfall's research and development unit, of which just over half are based in Älvkarleby. Cement is the material most researched in Älvkarleby, and the aim is to reduce the carbon footprint to near zero in cement production without compromising quality.

"Concrete must be usable for construction, have certain performance characteristics, and be strong enough to bear loads for many decades, perhaps centuries. Now that we are developing new concrete materials, we need to assist hydroelectric power and other energy sectors with guidance for their facilities", notes Erik Nordström. 

The cement crisis strengthened the demand

Today, cement accounts for 8 percent of the world's carbon dioxide emissions and has a significant climate impact. The demand for an alternative to traditional cement, also known as Portland cement, began in earnest around five years ago, explains Erik Nordström.

"Partly, this is due to various agreements on fossil-free infrastructure sectors and also the regulatory documents developed, including those for cement. Another driving factor was the crisis in cement production on Gotland, which prompted the question: What do we do instead?"

Conrete in the making.

The situation on the Swedish island Gotland, which made the dependence on mining virgin limestone for cement production critical, was exacerbated when Cementa, now Heidelberg Cement, did not get an extended permit in 2021 to continue this activity. Since then, legal battles over permitting have been numerous, resulting in uncertainty regarding traditional Portland cement production in Sweden.

Bojan Stojanovic, senior research and development engineer in building materials and energy technology at the research center in Älvkarleby, has focused on binders for climate-improved concrete over the past few years. 

This involves studying and mapping various types of low CO2 emitting cement and binders, as well as their overall function and application. It's evident that numerous kinds of by-products from the mining and steel industries, known as slag, are among the key components in binders with low carbon footprints.

From total reform to "harsh reality"

To explain how the work to reduce carbon dioxide in cement has progressed over time, Bojan Stojanovic likens it to something that begins with a total reform. "You think progressively and radically at first, but the further down the road you get, the closer you realise the "harsh reality" and you need to ask yourself several questions out of long-term perspective.

"This might include questions like who can manufacture a usable material in reality and in sufficient volumes, who can establish and realize a real and reasonable large-scale industrial manufacturing process? Who has access to the needed raw materials? If we place an order today, can we get something tomorrow?", says Bojan Stojanovic and continues:

"We are no longer in that phase where we look at all possibilities, now we see what we can actually use and obtain. I would say that we have not achieved our goal, we are a bit more than halfway towards fully being able to replace traditional cement with low-footprint cement."

Using slag products in cement manufacturing is not new; it has been done for several decades. The major difference is that back then it was all about reducing costs, not the carbon footprint as today.

"What they did was mix in all sorts of things, such as by-products from the steel industry. But the lack of knowledge meant they mixed everything possible, and then lifespan issues arose where some worked well and others turned out bad, explains Per-Erik Thorsell, emphasizing the need to thoroughly test and research new materials before manufacturing anything with them.

Critical to have access to accredited labs and expertise

To develop low-footprint cement, the material that constitutes the binder in concrete, Vattenfall's concrete laboratory tests various concepts from multiple cement producers. One of them is Swedish cement manufacturer Cemvision.

"For us, it has been critical to perform tests here at Vattenfall's accredited lab in Älvkarleby and to have access to the expertise available there. There are several different parameters you test the concrete against, such as long-term strength, frost resistance, chloride resistance, and carbonation, to name a few", says Cemvision's marketing manager Max Larsson von Reybekiel.

In June 2024, Vattenfall and Cemvision signed a cooperation agreement on the development and future deliveries of cement with near-zero carbon dioxide emissions. The parties also collaborate to demonstrate that it is fully possible to replace traditional cement, also known as Portland cement, with low-carbon footprint cement. But to seriously spur demand, the standardisation needs to be reviewed, notes Max Larsson von Reybekiel.

"The standards that exist today are written for Portland cement. They are generally very traditional and specify what raw materials can be included, which risks shutting the door to innovation. Around the world, there is a shift towards performance-based standards, which must be the next step in Sweden and the EU as well."

Max Larsson von Reybekiel, CMO Cemvision

Another factor crucial to the advancement of extremely low-carbon footprint cement is economic incentives.

"Large emitters, such as existing cement producers, currently have free allocations for emissions, but from 2026, these will be phased out. This means they will have to pay taxes on emissions, and by 2034, they will pay 100 percent. If manufacturers pass this cost on to customers, it could mean that cement may be about 300 percent more expensive around 2030", adds Max Larsson von Reybekiel.

How far have we come in phasing out traditional cement? For Vattenfall, the goal is for 10 percent of all concrete production to be made up of near-zero cement by 2030. This goal seems within reach, based on current knowledge.

Full-scale wind turbine with near-zero cement in sight

In the backyard of Vattenfall's concrete lab in Älvkarleby, they will soon cast a "slice" of a wind power foundation to demonstrate that it is possible to build at an industrial scale, explains Erik Nordström.

"We will follow up on the concrete's properties through measurement and sampling of the material before we can definitively say that this can be used to build a wind farm. Then you probably won't make an entire park at first but start with a couple of full-scale foundations."

The advantage of land-based wind farms is that the foundations will still be replaced within about 25 years because, for example, larger turbines are built. Additionally, these foundations are not subjected to as harsh conditions as hydroelectric power plants and offshore wind power, making land-based wind power a suitable application initially.

"Many may think the development is slow, but working with concrete technical properties takes a long time. Only verifying all properties in the lab takes a year, so the testing is time-consuming, concludes Erik Nordström.