Concrete has been used in construction for thousands of years and is everywhere. However, its production is a major contributor to the world’s carbon emissions and has seen a lot of research aimed at reducing its environmental impact.VTT One such project spun out of Finland aims to make concrete manufacturing carbon negative.
For decades, the VTT Technical Research Center in Finland has been investigating the negative effects of carbonation, where carbon dioxide is reabsorbed by concrete over time and can lead to corrosion of rebar.
In the late 2010s, researchers began looking at turning these problems into advantages. His Tapio Vehmas, senior scientist at VTT, said: “To find out how carbon dioxide works in concrete, how carboaluminates form, and how this process could replace cement and reduce carbon footprint. I started experimenting with.”
VTT/Jarno Altica
The search for suitable low-carbon binders has begun. These experiments revealed that blast furnace slag from the steel industry was carbonated and worked well as an effective binder replacing normal cement in concrete.
“This didn’t work right away, but we had to develop the material concept and find the right activator,” added Vehmas. “The final material combination for the binder consisted of slag, slush and bio-ash.”
The project then turned to commercialization, building an auto-carbonation pilot system that binds CO2 into precast concrete at atmospheric pressure, and installed it in a container located next to a concrete factory in Hollola, southern Finland. was installed in The owner of that plant, Rakennusbetoni-ja Elementti Oy, has since used the technology to create a carbon negative yard pavement for installation at the Skanska construction site.
Vehmas, current CEO of VTT spin-out Carbonaide, said: “Last fall, we demonstrated that replacing Portland cement with slag reduced the carbon footprint of our products to -60 kg/m3.” kg.
VTT
Carbonaide now plans to build the world’s first industrial pilot production line to produce carbon negative concrete and has secured €1.8 million (approximately US$1.95 million) in seed funding to get started. Hollola’s factory-scale unit, combined with a fully operational value chain, will “mineralize up to 5 tonnes of CO2 per day and increase production of carbon-negative concrete products by a factor of 100.” is expected.
The company aims to ramp up production and have 10 units operational across the region by 2026, which is expected to bind around 500 megatonnes of CO2 annually by 2050. The current pilot can be seen in action in the video below.
“At Carbonaide, our goal is not only to reduce the carbon footprint of construction materials such as concrete, but also to create a more sustainable future with cutting-edge technology that traps more CO2 than it emits over its lifetime. It’s about creating,” says Vehmas. “The built environment is the largest amount of man-made material, so it’s very natural for it to be a CO2 sink.”
Carbonaide’s first automated production line in Hollola
Source: VTT
