Concrete Could Soak Up CO2
July 30th, 2008
Cement maker Holcim is investigating the ability of concrete, particularly crushed concrete, to soak up carbon dioxide. In its latest newsletter, the company reports on Scandinavian research, which shows a process called re-carbonation occurs when concrete is crushed down to small sizes for recycling. This ability to bind CO2 and remove it from the atmosphere depends on a number of variables, including the type of concrete and its particular application. Initial studies suggest more than half the CO2 emitted in the production of Portland cement will be re-absorbed by concrete over a 100-year period.
Holcim notes there is a dearth of knowledge in NZ about the re-carbonating ability of demolished and crushed concrete.
This means the cement industry’s contribution to NZ’s CO2 emissions is likely to be considerably over-estimated. Holcim says the key message of the Scandinavian work is the greater the effort made to recycle old concrete by crushing it, the greater the re-carbonation rate. Holcim’s ongoing research will focus on creating optimal conditions for re-carbonation of concrete and gaining a better understanding of the timeframes over which it takes place.
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