Increasing the use of recovered mineral components in cement or concrete

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Courtesy of US EPA - The Office of Solid Waste (OSW)

Section 6017(a) of the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users, P.L. 109-59, Aug. 10, 2005 (SAFETEA-LU), directs the U.S. Environmental Protection Agency (EPA or the Agency) to, “…conduct a study to determine the extent to which procurement requirements, when fully implemented…may realize energy savings and environmental benefits attainable with substitution of recovered mineral components in cement used in cement or concrete projects.”

SAFETEA-LU directs EPA to submit a report to Congress within 30 months of the enactment of SAFETEA-LU that addresses the following requirements:

(A) Quantify (i) the extent to which recovered mineral components are being substituted for portland cement, particularly as a result of current procurement requirements; and (ii) the energy savings and environmental benefits associated with that substitution;

(B) Identify all barriers in procurement requirements to greater realization of energy savings and environmental benefits, including barriers resulting from exceptions from current law; and

(C) (i) Identify potential mechanisms to achieve greater substitution of recovered mineral components in types of cement and concrete projects for which recovered material components historically have not been used or have been used only minimally; (ii) evaluate the feasibility of establishing guidelines or standards for optimized substitution rates of recovered material component in those cement and concrete projects; and (iii) identify any potential environmental or economic effects that may result from greater substitution of recovered mineral components in these cement and concrete projects.
Energy savings and environmental benefits associated with substitution.

Recovered mineral component (RMC) use yields positive environmental benefits through lower resource consumption. To overcome procurement data limitations, for ground granulated blast-furnace slag (GGBFS), coal combustion fly ash (coal fly ash) , and silica fume, the report derives estimates of their use in Federal projects by roughly apportioning total volumes to Federal and non-Federal projects (based upon the estimated proportion of total cement demand related to
federally-funded projects). For the years 2004 and 2005, our life cycle analysis indicates that the use of GGBFS, coal fly ash, and silica fume in Federal concrete projects alone resulted in significant reductions in greenhouse gas (GHG) emissions, criteria air pollutants, and energy and water use. For these two years combined, the analysis indicates reduced energy use of 31.5 billion megajoules, avoided CO2 equivalent air emissions of 3.8 million metric tons, and water
savings of 2.1 billion liters. The report further illustrates how these benefits may accrue over a longer time period (through 2015) given alternative use scenarios. This aspect of the analysis also links to issue C noted above.

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