The global effort to reduce greenhouse gases has certainly, and for good reason, taken a firm hold of the construction materials market. There has been a particular bullseye on portland cement manufacturing. Why? Well, being the second most consumed commodity on the planet (1st being water), the production of portland cement is one of the leading emitters of greenhouse gases accounting for approximately 8% of overall global CO2 emissions per https://psci.princeton.edu/tips/2020/11/3/cement-and-concrete-the-environmental-impact.[1]
To reduce greenhouse gas, one first must be able to measure it. EPDs or Environmental Product Declarations are essentially this reported measurement. An EPD is the equivalent of a Nutrition Facts label we have all grown so accustomed to seeing on every food item we consume but made for the products we use daily to create the homes, buildings, skyscrapers, foundations, roads, tunnels, and bridges we use all around the world. The primary tracked component of an EPD is its GWP or Global Warming Potential, which is a measurement of how much CO2 is emitted when 1 ton of the material is produced.
Industry associations have already begun to report to the world their respective products' EPDs. The American Institute of Steel Construction reports for every 1 ton of hot-rolled steel produced there is an industry average of 1.22 tons of CO2 emitted. Now that there are EPDs (and GWPs) being reported, we have the benchmarks to begin to track the reductions needed by all CO2-emitting industries. And that is exactly what is already taking place - industries are reducing their outputs and the cement and concrete industry is no exception.
The Portland Cement Association (PCA) reports that for every 1 ton of portland cement produced an industry average of 919 kg of CO2 is emitted.
How do we improve and reduce? One of the most effective ways to reduce the GWP of concrete is to reduce the clinker content in the cement and reduce the cement content in concrete. The most recent widespread method to do this to date is to use PLC (portland limestone cement) which has an increased amount of limestone dust and therefore a lower amount of clinker and overall, a decreased amount of portland cement in the resultant concrete. The PCA reports the industry average of PLC is 844 kg of CO2 per 1 ton of PLC produced. We're going in the right direction!
The utilization of SCMs (supplementary cementitious materials) like the products R-E-D supplies and has supplied for close to 15 years, is the next biggest step in reducing the GWP of concrete. For example, the GWP for R-E-D's Ground Glass Pozzolan (ReAct 4TM) is 51 kg of CO2 per ton of ReAct 4TM produced - that's one of the lowest amounts of CO2 emitted for a produced cementitious material on the planet!
Reference:(2020) “Cement and Concrete: The Environmental Impact” https://psci.princeton.edu/tips/2020/11/3/cement-and-concrete-the-environmental-impact. Retrieved on Dec. 2023