Boral has successfully recycled concrete using aggregates that were recarbonated via carbon capture from a cement plant.
The milestone trial saw recycled concrete aggregates from Boral’s Widemere recycling facility used as feedstock to capture and permanently store CO2 from the flue gas diverted from Berrima Cement Works’ operations into its recently commissioned recarbonation-based carbon capture and storage (CCS) pilot plant.
The recarbonated recycled aggregates resulting from this process were then used to partially replace natural coarse aggregates in a low carbon concrete mix.
Boral head of sustainability and innovation Ali Nezhad said they are proud to lead the development of utilisation pathways for recarbonated concrete aggregates.
“Its successful use not only enhances the viability of recarbonation-based carbon capture technology but also offers the potential for a further reduction in the embodied carbon of concrete by replacing natural aggregates,” Nezhad said.
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“The success of our carbon capture pilot plant at Berrima further validates the potential of recarbonation and underscores the importance of its broader recognition.”
One of the unique properties of concrete is that it absorbs carbon dioxide through its service, life and end of life phases. This process – cement recarbonation – occurs over many years. At end of life, when structures containing concrete are demolished, the concrete is crushed, its exposed surface increases which accelerates the recarbonation rate.
The recarbonation process at Berrima CCS plant accelerates the natural carbonation of recycled aggregates by exposing them to controlled process conditions.
Boral’s concrete field trial was conducted at its Maldon cement manufacturing facility. The trial and CCS pilot plant’s construction were jointly funded by the Federal Government’s Carbon Capture, Use and Storage (CCUS) Development Fund and Boral. The project involved replacing 50 per cent of the natural coarse aggregates in Boral’s low-carbon Envisia concrete with recarbonated recycled aggregates.
Boral chief executive officer and managing director Vik Bansal said the company is committed to a lower-carbon future.
“…we believe recarbonation will play an important role in decarbonising the cement and concrete industry,” he said.
“The successful accelerated recarbonation of recycled concrete aggregates at our CCS pilot plant at Berrima and utilisation of these aggregates in concrete further reinforce the potential of this technology.
“Alongside our significant investments in alternative fuels and alternative materials to decarbonise our cement manufacturing operations in the short term, we remain committed to exploring technologies like carbon capture and storage as part of our long-term journey towards our net zero ambition by 2050.”