Concrete Producers Paid for Substituting Supplementary Cementitious Materials Instead of Portland Cement

(Aggregate Research 2-4-2011) Several innovative concrete producers are earning financial incentives through Cool Climate Concrete (C3), a greenhouse gas offset program, for substituting supplementary cementitious materials (SCMs) for portland cement during concrete production in the United States. These producers receive an incentive of $4 per metric ton of avoided carbon dioxide (CO2) emissions resulting from reducing portland cement use beyond established baselines.
Now in its second phase, the program has $800,000 allocated for incentives available through September 2012. The program is managed by the sustainable materials consulting firm West Main Consultants, LLC, and is one of several offset projects funded by the Climate Trust, an Oregon nonprofit. Incentives during the first phase totaled $125,000 for 250,000 metric tons of verified avoided CO2 emissions, ranging from $600 to $68,000 and averaging $11,000 per company over the course of participation.
Ready mixed concrete manufacturers and concrete products manufacturers who purchase portland cement and SCMs from suppliers to blend their own cement during concrete mixing in the United States are eligible to participate.
Companies participating in C3 provide consumption and production data for the past three years to establish quarterly baseline cement to concrete ratios (percentage of cement per cubic yard), and provide similar data on an ongoing quarterly basis to determine avoided emissions. All participating company data is kept confidential. Offset generation is based on decreasing company- specific cement to concrete ratios below established baselines.
While numerous SCMs are used in concrete production, only five have been approved as a portland cement substitute under the C3 program: ASTM C618 Fly Ash, ASTM C989 Grade 100 or 120 Ground Granulated Blast Furnace Slag (GGBFS), ASTM C1240 Silica Fume, Rice Hull Ash and Cement Kiln Dust. These were selected because they do not represent a net increase in emissions as they are byproducts of other processes (except in the case of GGBFS, where associated emissions are accounted for in program calculations).
By incentivizing the replacement of portland cement in concrete mixes, C3 helps concrete producers:

  • Reduce mix costs by rewarding increased replacement of portland cement with SCMs.
  • Lower carbon footprint by reducing portland cement use per cubic yard.
  • Track sustainability performance for free, based on actual consumption and production data.
  • Gain recognition for steps taken towards more sustainable practices.

To assist companies in taking full advantage of participation, an analytical tool tailored to each company is provided to evaluate potential offsets and incentives that could be generated at various portland cement reduction levels. This tool facilitates a better understanding of the correlation between cement reduction and offset generation, and may be valuable in establishing sustainability goals.
By capitalizing on the innovative use of SCMs through the C3 program, concrete producers are not only receiving program benefits, but are furthering the economic and environmental sustainability goals of the concrete industry as a whole through mix ingredient optimization, program incentives, utilizing industrial byproducts, and reducing portland cement use. 
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