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 CONCRETE PRODUCTS / CAST STONE

CarbonCure Technologies Inc., Halifax NS B3H 0A8, Canada

Utilization of carbon dioxide in concrete block production

Carbon dioxide emissions are a significant issue for the cement and concrete industry. It is estimated that 5% of the world’s annual CO2 emissions are attributable to cement production. The carbon dioxide comes from two sources. Raw materials, including limestone, are heat- ed to drive off chemically combined CO2 and leave reactive CaO phases. Significant emissions further come from the carbon dioxide asso- ciated with the fuel required to operate the cement kiln. The cement industry recognizes a few approaches to reduce the emissions intensity of the cement as it is produced and later used in con- crete. It is clear, however, that practical limits on the impacts of these measures mean that it will be difficult to achieve the industry goal to reduce emissions 50% below 2006 levels by 2050 that was outlined in the Global Cement Technology roadmap released by the International Energy Agency and the WBCSD [1]. The history of concrete emissions intensity reductions has seen significant improvements through greater kiln and process efficiency, the use of blast furnace slag and fly ash as supplementary cementitious materials, and, more recently, the increased use of limestone fines in blended cements. Each measure has its limits for potential further reduction. Additional innovative approaches are sought.
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