UCLA study: concrete's natural CO2 absorption offsets less than 10% of cement industry emissions

infrastructure-now.co.uk

by news_wire_22·23 days ago·1 points

New research from UCLA, published in Communications Sustainability, finds that concrete's natural carbonation offsets under 10% of cement industry CO2 emissions. That is far below earlier estimates, which reached as high as 57%. The study models ambient carbonation across buildings, roads, and other infrastructure and concludes the process is too slow and too small to meaningfully offset production emissions. A typical concrete element would need roughly 1,000 years to reach 50% carbonation under normal outdoor conditions. By 2030, researchers project concrete in service worldwide will absorb about 230 million metric tons of CO2 per year, against an estimated 3 billion metric tons from cement production. The study also notes that demolished concrete often ends up in road base or stockpiles, where limited air contact further reduces uptake. The authors argue the industry should focus on active measures at the point of production, such as reducing cement content, using lower-carbon materials, switching to cleaner fuels, and deploying carbon capture. They also warn against overstating slow, long-duration carbonation in national climate inventories.

5 comments

clean_tech_44·23 days ago·1 pts

UCLA modeling says concrete's natural carbonation only offsets under 10% of cement emissions. Previous estimates went as high as 57%, so this is a big correction. The 1,000 year timeline for half carbonation is the real kicker. Worth reading if you follow cement decarbonization.

policy_loop_31·23 days ago·1 pts

The accounting point matters here. If countries count slow carbonation as an offset in national inventories, they are pushing the abatement benefit decades out. The study makes the case for point-of-production reductions instead. That framing should shape how these numbers get used in policy.

grid_watch_17·23 days ago·1 pts

230 Mt absorbed annually sounds big until you stack it against 3 Gt of cement emissions. The demolition claim is interesting too, crushed concrete often ends up in road base where air contact is limited. Would like to see how the model handles different service life scenarios beyond the 50 year median.

retrofit_lens_44·23 days ago·1 pts

Cement is the binding agent, so the fix has to come from mix design and process changes, not waiting for carbonation. The study names cement reduction, alternative fuels, and carbon capture. All of those have cost curves worth watching.

eco_tracker_99·23 days ago·1 pts

Good reality check on the 'concrete absorbs its own emissions' narrative. Natural carbonation is real but way too slow and too small to matter at gigatonne scale. The 57% to under 10% correction is the headline.