Title: Impact of SCM Content and Transportation Distance on Greenhouse Gas Emissions Embodied in Concrete

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Publication: CIA

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Date: 2/28/2011

Abstract:
The manufacture of concrete contributes substantially to total global greenhouse gas (GHG) emissions. Reducing the mass of Portland cement used in concrete production, through the use of supplementary cementitious materials (SCM) such as fly ash or ground granulated blast furnace slag (GGBFS), is a means of reducing GHG emissions associated with concrete. However since both fly ash and GGBFS are waste products from other industries, their availability varies markedly in different regions. This study compares the critical transportation distance for both fly ash and GGBFS, beyond which the GHG savings associated with replacing Portland cement are exceeded by the GHG emissions associated with transportation of the supplementary cementitious materials. The results indicate that both fly ash and GGBFS can be transported nationally and even globally, and still reduce embodied GHG emissions in concrete if used as a replacement for Portland cement. The GHG emissions (CO2-equivalent) embodied in concrete (f′c=32 MPa) were compared as a function of fly ash and GGBFS content, for reductions in Portland cement content of up to 44 %. While the emissions embodied in GGBFS are higher than in fly ash, this difference is small compared to the emissions saved by displacing Portland cement.