PCR, EPDs, and Quantifying the Environmental Impacts of Cement and Concrete
Like all construction materials, cement and concrete each have an environmental footprint. At present, the most widely accepted approach for quantifying the potential environmental impact of a material is to use a Product Category Rule (PCR) to develop an Environmental Product Declaration (EPD). A PCR is a set of rules, requirements, and guidelines for developing an EPD, which is an independently verified and registered summary report of environmental impacts of a material’s production. By referencing appropriate standards, a PCR helps to ensure that EPDs for similar products are developed from comparable data and analysis methods.
The PCR for cement only looks at the manufacturing aspect and as such is considered a “cradle-to-gate” PCR. While there are other impacts beyond the plant where cement is produced, establishing the boundary as the cement plant allows for quantifying the environmental impacts associated with producing a specific quantity of cement (one metric ton is the usual metric).
EPDs have been compared to the nutritional label found on food products: they provide a clear, consistent, and transparent basis for reporting broad environmental performance for similar types of materials or products. EPDs do not tell the full story about the impact of construction, just the manufacturing aspect for a material. To understand the full impact of using cement, it would be necessary to develop a life-cycle assessment (LCA) of the project where the cement was used; this would include environmental impacts from transportation to the site, construction using the cement, service life (use phase) of the structure, and even end of life.
As the name implies, industry-wide EPDs can be developed to represent an average of production impacts across many manufacturers and must be based on the same PCR. The EPDs are valid for five years after the date of publication. At that time, another survey is conducted to collect new data so that any advancements or other changes within the industry can be picked up. In early 2021, four new industry-wide EPDs based on the 2020 Cement PCR (NSF 2020) were published to cover the four main categories of cement; ASTM C150 portland cement, ASTM C595 portland-limestone cement, ASTM C595 blended cements, and ASTM C91 masonry cement produced in North America. The EPDs and PCR for cement are posted at ASTM International and provided below for convenience:
• EPD for portland cements – industry wide
• EPD for portland-limestone cements - industry wide
• EPD for blended hydraulic cements - industry wide
• EPD for masonry cements - industry wide
• PCR for portland, blended hydraulic, masonry, mortar, and plastic stucco cements