Webcor Concrete is taking bold steps to reduce the carbon footprint of its projects by experimenting with innovative, low-carbon concrete alternatives to traditional Portland Cement, a significant contributor to global carbon emissions.
Traditional Portland Cement accounts for approximately 8 percent of global CO₂ emissions due to the chemical processes and high heat required in production. As part of Webcor's decarbonization initiative, Webcor Concrete has been actively testing novel materials that could dramatically reduce this environmental impact while maintaining structural integrity and workability.
The Webcor Concrete team recently reached a significant milestone at the UC Berkeley Student Housing #2, successfully pouring nine cubic yards of innovative C-Crete material through a 47-meter pump for a mud slab application.
C-Crete is a groundbreaking technology that uses zero Portland Cement. Instead, it employs a geopolymer process that works with different ores and blast furnace slag.
Christophe Allard-Moreau, project manager for Webcor Concrete, explains: "C-Crete is a sustainable concrete option that uses zero Portland Cement and even captures carbon dioxide during its curing process, helping to reduce the carbon footprint of construction."
According to Eric Peterson, Director of Webcor Concrete, "C-Crete was founded by Dr. Rouzbeh Savary based on his PhD work at MIT. What interests me about his company is that it won't depend on slag, which has a limited supply, once it can scale operations. He's already proven in lab settings the ability to use other calcium silicate ores."
While the initial pour experienced slower setting times than anticipated due to an abundance of caution with hydration stabilizers, the experiment provides valuable insights for future applications. The concrete achieves strengths over 5,000 psi, demonstrating its potential as a viable alternative for many applications.
David Bischoff, senior project manager for Webcor Concrete, oversaw another experimental concrete pour at UC Berkeley's Substation 8 project. This pour used Fortera, another cement substitute under development. The project team, including Superintendent Barret Neumayr and Project Engineer Nickolas Borov, spearheaded this effort. The team is planning another placement of the Fortera mix in the first two weeks of April.
Currently, Fortera functions primarily as a powdered limestone filler, and work is ongoing to develop more reactive properties. According to testing conducted by Vulcan Materials Company, optimized performance occurs at 12 percent Portland Cement replacement, resulting in higher early-age strength, lower shrinkage, and equivalent set times in standard low-carbon mixes.
Eric Peterson emphasizes the importance of field testing: "It's important to understand that Fortera is still in its early stages. Currently, it's functioning primarily as a powdered limestone filler with very little reactivity. While their testing shows promising results at 12-percent replacement levels, we're participating in these field tests because companies developing new materials must get real-world feedback. This collaboration helps advance the technology and gives Webcor firsthand knowledge of which sustainable materials are ready for specific applications and when they might be viable for general use."
In Southern California, the Webcor Concrete team has successfully trialed Limestone Calcined Clay Cement (LC3) at its Grandview project, where Webcor Concrete subcontracts for United Builders. LC3 was used for concrete pads and curbs.
Kyle Vasa Bertolucci, Webcor Concrete project director in Southern California, reports that this mix demonstrated a 19-percent lower Global Warming Potential (GWP) than an equivalent Portland mix.
"Feedback was pretty good. It placed fine, finished all right, with a slightly different beige-grey color that the place-and-finish team could identify."
While LC3 is not new globally—many parts of the world already use it—it represents a new entry into the California market. The trial was conducted in partnership with National Concrete, our ready-mix supplier.
"Ultimately, our real goal is to further testing and validation that it's a durable mix and convince suppliers like National to dedicate silo space to lower GWP cements," Bertolucci explains. "This was only a 4,000 psi mix—we're still working on seeing how it performs with higher-strength applications of 8,000-10,000 psi."
These trials represent Webcor's commitment to environmental responsibility and innovation in construction. By actively testing emerging low-carbon technologies, we position ourselves at the forefront of sustainable building practices while gathering critical data that will inform future projects and aid in developing these essential alternatives.
The Low Carbon Concrete Working Group established by Owen Brizgys is a critical part of this effort. This group is instrumental in providing insights for new and potential projects and ensures Webcor remains updated on emerging sustainable solutions.
As one of our decarbonization working group's primary goals, these experiments with novel materials help us determine what can be safely incorporated into projects with stretch goals for low carbon footprints. Through continued testing and partnership with suppliers and technology developers, Webcor continues to lead the industry toward a more sustainable future.
