Boral trials concrete with aggregates recarbonated via carbon capture

Boral has announced that it has successfully produced concrete made with recycled concrete aggregates that have been recarbonated via carbon capture technology from its integrated cement manufacturing plant.

The trial, the first of its kind in Australia according to the company, 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 says this milestone demonstrates a viable pathway for using products from recarbonation-based carbon capture technology, which Boral is currently trialling at its Berrima cement plant.

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, commonly into recycled concrete aggregates, and its exposed surface increases, accelerating 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 Australian Government’s Carbon Capture, Use and Storage (CCUS) Development Fund and Boral. The project involved replacing 50% of the natural coarse aggregates in Boral’s low-carbon Envisia concrete with recarbonated recycled aggregates.

The recarbonation CCS process offers a practical, low-cost solution for capturing and permanently storing carbon dioxide from cement manufacturing. Carbon capture, utilisation and storage is a critical decarbonisation lever for addressing process emissions, which account for approximately 65% of carbon emissions in cement production.

“We’re proud to lead the development of utilisation pathways for recarbonated concrete aggregates,” said Dr Ali Nezhad, Head of Sustainability and Innovation at Boral. “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.

“The success of our carbon capture pilot plant at Berrima further validates the potential of recarbonation and underscores the importance of its broader recognition.”

“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,” said Vik Bansal, CEO and Managing Director.

To learn more about recarbonation visit: boral.com.au/sustainability/recarbonation.

Image credit: Boral