A Designer’s Dilemmas: Specifying More Sustainable Concrete
At the American Concrete Institute (ACI) Fall Convention, I shared a presentation on the options designers have when trying to reduce the embodied carbon of concrete on their project. This video replay discusses several 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.
American Concrete Institute Fall Convention 2022