A New Standard for Replacing Cement with Recycled Glass
Ground glass can be a low-global-warming-potential replacement for Portland cement, but using it on a project has been difficult because there has been no standard way to specify the material. ASTM has published ASTM C1866, Standard Specification for Recycled Ground-Glass Pozzolan for Use in Concrete. ASTM C1866 will make it easier for building teams to replace a percentage of Portland cement with recycled ground glass supplementary cementitious materials (SCMs, sometimes called pozzolans)—an important step forward for the green building industry.
The production of Portland cement used in concrete is responsible for approximately 5% of total global CO2 emissions, so replacing some of the Portland cement with post-consumer ground glass can significantly reduce concrete’s carbon footprint. As a bonus, ground-glass pozzolans make use of a readily available regional waste material that is often landfilled instead of recycled, and it can be used in place of fly ash (which can contain toxic heavy metals) and ground granulated blast furnace slag, both of which are byproducts of carbon-intensive industries.
Processed into a fine powder, ground glass can replace up to 40% of Portland cement in a mix, creating a stronger, denser, less permeable, and more durable concrete while making use of a readily available, inert waste material. Pozzolans such as ground glass can also improve concrete’s workability and reduce the amount of water and chemical admixtures required.
The ground glass pozzolan Pozzotive, made by Urban Mining and a former BuildingGreen Top 10 product, has been used successfully in concrete masonry units (CMUs) and bricks for years and is available as an SCM for ready mix. With the adoption of ASTM C1866, products like this can now be used more readily.
Ehrlich, B. (2020, May 20). A New Standard for Replacing Cement with Recycled Glass. Retrieved from https://www.buildinggreen.com/newsbrief/new-standard-replacing-cement-recycled-glass