Title: A Designer’s Dilemmas: Specifying More Sustainable Concrete

Author(s): Alec Zimmer

Publication: Web Session

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Date: 10/23/2022

Abstract:
When trying to reduce the embodied carbon of concrete, designers have a number of options. But these options come with severe challenges: - We can specify partial replacement of the portland cement with interground limestone or supplementary cementitious materials, but SCMs may not be available or may require a long (carbon-adding) journey to reach the batch plant. - We can specify carbon sequestration techniques, but those techniques are not available yet in all regions. - We can aspire to better particle packing of the aggregates, but the local producers may not be able to achieve the blend of aggregate sizes to make this a reality. - We can specify a longer period of time to achieve the specified strength and reduce the cement content, but: > Doing so is often at odds with aggressive construction schedules. > Due to the fact that testing quality is variable, suppliers often "over cement" concrete mixes to guard against low-strength test reports. - Most fundamentally, the design-and-construction community operates in an environment that, due to perceived risk and fee pressure, effectively discourages the additional thought and vetting that comes with innovation.