This is the fourth installment in our four-part blog series examining where the industry stands today in capturing the value of supplementary cementitious materials (SCMs). Since the benefits of SCMs scale directly to how much portland cement is replaced, having a reliable supply is critical for success. Heidelberg Materials has taken a comprehensive approach to increasing SCM supply, both by opening and upgrading facilities and by developing new technologies that boost output. The result is enhanced access to SCMs, supporting stronger performance in your concrete and greater sustainability on your projects!
Installments of this series were first published as the article "What’s Up with SCMs?” in the NRMCA’s Concrete InFocus magazine, Winter, 2025.
A new SCM, from recycled concrete, has been developed by Heidelberg Materials. Typically, the concrete recycling process involves crushing demolition concrete and returning it to use as an aggregate in new concrete mixes or as rubble in applications such as road bases. Heidelberg Materials’ patented ReConcrete process mechanically breaks down demolition concrete into its original constituents. The resulting materials include sand and gravel which can be used in lieu of virgin raw materials and recycled concrete paste (RCP), which is the finest fraction of the separation process. ReConcrete technology takes RCP and puts it to use either as an alternative raw material for clinker production, replacing limestone and reducing CO₂ emissions, or as an SCM.
When using RCP as an SCM, the carbon-savings benefits go beyond the paste’s value as a straightforward replacement for other cementitious materials. RCP can act as a carbon sink, absorbing and permanently binding CO₂ over the entire lifespan of an infrastructure or building project.
To maximize RCP’s carbonization potential, it can also be exposed to raw exhaust gases from cement production, where it initiates what is known as “enforced carbonation.” The resulting carbonated RCP (cRCP) has the potential to mineralize about 150 kg CO₂ per tonne of RCP, significantly reducing CO₂ process emissions caused by carbon‐intensive clinker production.
To further explore this technology, Heidelberg Materials recently opened an industrial pilot facility for enforced carbonation at its cement plant in Górażdże, Poland. The RCP, obtained at a recycling plant near Katowice, Poland, will be transported to the pilot facility in Górażdże, where it will be exposed to the exhaust gases from the kiln. Development of ReConcrete combines the goals of circularity with decarbonization, and the Polish facility will establish a blueprint for global scale-up. [Read more about ReConcrete here.]
The future of construction lies in our ability to innovate responsibly, and the use of SCMs is a powerful step in that direction. By incorporating SCMs, engineers and designers not only enhance the performance and durability of their structures but also contribute to a more sustainable built environment. The choice to adopt SCMs is more than a technical decision—it is a commitment to building better for the generations to come.
Contact Heidelberg Materials today to learn more.
To catch up on earlier installments in our series, click here to read Part 1, “The Benefits of SCMs” and here to read Part 2, “Expanding Availability of Slag Cement” and here to read Part 3, “Fly Ash Reclamation.”