Carbon-eating blocks ingest eight tonnes of CO2 a day, says company

The carbon-negative concrete blocks absorb more CO2 during production than they emit.
Loukia Papadopoulos
A construction site..jpg
Representational image: A building under construction.


A Limburg (Netherlands) company called Masterbloc has engineered an eco-friendly building material from steel slag left over from the steel industry, according to an article by The Brussels Times on Saturday.

Masterbloc's product is CO-2 negative, with more CO2 absorbed during production than emitted. At the company's factory, some 8- tonnes of CO2-ingesting building blocks are produced per day. This roughly accounts for a yearly output of 15,000 tonnes. 

The company CEO Bjorn Gubbels claims the block stores CO2 and can help boost the circular economy.

"There are all kinds of stacking blocks on the market, and they all look very similar, however, Masterbloc is different to other stacking blocks. We return to the days when stacking blocks was child's play. Indeed, this is exactly the principle that we apply in the real world," says Masterbloc on its website, hinting at the product's unique nature.

The company has ambitious plans to rapidly expand the production of building materials in the coming years. The new production process will be presented to Flemish Minister Zuhal Demir in December.

The technology for Masterbloc has been developed by Genk-based recycling company Orbix, which has been processing steel slag from stainless steel producer Aperam since 1996.

Research and development

It all began in 2004, when Orbix's research and development manager Dirk Van Mechelen discovered that steel slag residue was hardening after exposure to CO2. Working with researchers from the Flemish Institute for Technological Research (VITO), the technology was further developed in 2011, resulting in the "Crabstone" process.

Carbon-eating blocks ingest eight tonnes of CO2 a day, says company
A construction site with Masterbloc material.

"Carbstone has numerous advantages," Serge Celis, CEO of Orbix, told The Brussels Times.

"Thanks to Carbstone, we convert metal slag into a high-quality circular product and since CO2 is used as a binder, we avoid using cement, which accounts for 10% of global CO2 emissions."

Better yet, Masterbloc blocks have the same quality as conventional blocks making the technology increasingly popular with companies seeking to reduce their CO2 emissions. In addition, by using CO2 as a binder, construction companies are no longer dependent on cement prices.

The Carbstone technology has even been expanded to make roofing tiles, bricks, and clinkers. 

Other companies

Mastebloc is not the only company to produce such technology. One Montreal-based (Canada) technology company, called CarbiCrete, is also producing an alternative concrete that absorbs carbon dioxide instead of releasing it into the atmosphere.

"For every ton of concrete produced using the CarbiCrete process, 150 kg (kilogram) of CO2 are abated/removed," Yuti Mytko told IE in October. 

Better yet, the company offers concrete manufacturers the process and support to implement this replacement technology in their existing plants. 

"Each block of 18kg represents up to 3kg of CO2 abated/removed than conventional, cement-based blocks," explained Mytko. 

In December 2021, France built the first ever carbon-negative building, and it was made of hemp. A French architecture and landscaping company from the town of Croissy-Beaubourg unveiled the country's first hempcrete public building: Pierre Chevet sports hall.

The 4,000-square-foot (380 square meters) building includes an exercise hall and changing rooms. Hempcrete is a mixture of hemp with lime and water, and it's another carbon-negative way of engineering buildings.

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