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Papers » Conventional masonry is used widely throughout the world to construct durable, cost effective buildings. However, studies have shown that the production of Portland cement is responsible for 6-7% of global greenhouse gas emissions, and accounts for 91% of the embodied carbon of conventional cement-based masonry blocks. This paper presents new research that compares carbon dioxide equivalent (CO2-e) of conventional cement based masonry blocks to emissions of new structural masonry alternatives entering the marketplace. Alkali activated soil masonry units (AASMU) and dynamically compacted soil masonry units (DCSMU) are emergent masonry materials that contain the promise of providing durable cost-effective performance while significantly reducing carbon emissions. The research compares individual DCSMU and AASMU blocks and assemblies to conventional CMU blocks and assemblies in a cradle to gate analysis of embodied carbon due to materials and manufacturing processes. Two scenarios are investigated. The first is based on current production methods, while the second scenario anticipates changes to manufacturing methods and considers their likely effect on CO2 emissions. Preliminary results show that assemblies consisting of DCSMU with low cement grout can reduce CO2-e emissions by as much as 52% when compared to conventional CMU assemblies. In contrast, AASMU blocks, which completely eliminate the use of ordinary Portland cement, reduce CO2-e emissions by only 28% under present production scenarios, due to the energy required to produce the alkali activators. Despite the modest emission reduction of AASMU blocks, it is anticipated that future changes to alkali activator production methods will significantly reduce emissions of AASMU, making them among the most sustainable masonry materials.

Author(s):

Joseph Dahmen
University of British Columbia
Canada

Jose F. Muñoz
Watershed Materials LLC
United States