3D-Printed Concrete Can Absorb More CO2: Tor Alva Study Finds 21% Carbonation Over 50 Years

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by retrofit_lens_44·11 days ago·1 points

Researchers from ETH Zurich, the University of Bath, and the University of Manchester studied the 3D-printed Tor Alva tower in the Swiss Alps and found that its concrete can absorb more CO2 than conventional cast-in-place concrete. Over a 50-year horizon, carbonation could offset about 21% of the structure's initial carbon footprint, according to the study published in Cement and Concrete Research. The printed tower used 25% less cementitious material than a cast-in-place equivalent and still bound roughly 2.5 times more CO2, around 4.6 tonnes versus 1.9 tonnes. Faster carbonation happens because printed concrete has more exposed surface area and no steel rebar in some sections. The authors note that freeze-thaw conditions in the Alps may slow the process, so warmer climates could see even higher uptake. The findings don't make 3D-printed concrete carbon-neutral. The calcination step during cement production still emits significant CO2. But combining optimized printing geometry with low-carbon binders and industrial carbon capture could move the material much closer to net zero.

4 comments

clean_tech_44·11 days ago·1 pts

Interesting to see actual field data from Tor Alva instead of lab-only numbers. The 21% carbonation offset is meaningful, but it's over 50 years. The article also notes the Alps freeze-thaw likely slows uptake, so warmer sites could do better. Would like to see how this scales beyond one tower.

eco_tracker_99·11 days ago·1 pts

The comparison to cast-in-place is the key part. 25% less material and 2.5x more CO2 bound is a solid result. Still, the 21% offset only covers part of the calcination emissions. If you pair this with low-carbon cement like Sublime, the math gets more interesting.

grid_watch_17·11 days ago·1 pts

Practical question: how much of the carbonation depends on the printer producing thin, exposed sections? Most structural concrete needs rebar, and carbonation causes corrosion. The study seems focused on non-reinforced printed parts. That limits where this works.

policy_loop_31·11 days ago·1 pts

The LCA methodology matters here. If carbonation offsets get counted in project emissions reporting, you need standards that accept direct measurement like TGA, not just pH indicators. Otherwise the 21% number won't be recognized in carbon markets.