Cement recycling – a cost-effective and efficient way
The recycling of cement paste offers a low-cost and effective method of reducing emissions in cement production, as a new study by Imperial College London shows. With a reduction of up to 15% in emissions, this technology opens up promising prospects for the construction industry.
The study recently published in the journal PNAS, led by Imperial College London and in collaboration with Empa and EPFL, shows that recycling cement paste from demolished concrete is one of the most effective and economical ways to reduce CO2 emissions. The process of CO2 mineralization, in which CO2 is absorbed into building materials such as concrete, could reduce emissions from cement production by around 15% – equivalent to 0.8% of global greenhouse gas emissions in 2020.
Cementpaste recycling is the frontrunner among the technologies
Of the ten CO2 mineralization technologies examined, recycled cement paste proves to be the most promising. Cement paste, a binding agent for concrete, usually comes from demolished buildings and can be processed at low cost. Rupert J. Myers from the Department of Civil and Environmental Engineering at Imperial College emphasizes: “Our results show that CO2-mineralized cement could be a key technology for decarbonizing the construction sector.”
Economic benefits and sustainability
The study highlights that cost-effective CO2 mineralization technologies are up to five times cheaper than conventional carbon capture and storage methods. In addition, they offer a long-term solution, as building materials can store CO2 for centuries. Justin D. Driver from the Department of Chemical Engineering at Imperial College adds: “While CO2 mineralization is not an all-purpose solution, it offers great potential for reducing emissions in the construction sector.”
Limitations and further research needed
Ellina Bernard, a scientist at Empa’s Concrete and Asphalt Laboratory, points out that the amount of material available for carbonation is limited, which restricts the potential of this technology. Nevertheless, the potential CO2 savings of 15% are significant. Further research to optimize and reduce the cost of carbon capture and utilization (CCU) technologies remains essential.
Recommendations for the future
The study formulates concrete recommendations for political decision-makers, investors and researchers:
- Develop strategies to support the recycling of concrete demolition: the aim is to promote the recycling of concrete demolition in order to maximize emission reductions.
- Focusing on competitive CO2 mineralization technologies: The focus should be on developing and supporting those technologies that have proven to be economical and effective in making optimal use of resources.
Ensure transparency in the competitiveness of these technologies: To enable investors to make informed decisions, clear and comprehensible information must be provided on the costs, market opportunities and possible applications of the various technologies.