Cement-free concrete is revolutionizing the construction industry by eliminating cement, a major contributor to greenhouse gas emissions, from its mix. This innovative material aims to significantly reduce the environmental impact of traditional concrete.
Innovative Alternatives
Instead of cement, cement-free concrete utilizes alternative binding agents, often derived from industrial byproducts. One common approach involves Alkali-Activated Cementitious Materials (AACM), which activate pozzolanic substances like ground granulated blast-furnace slag (GGBS) and pulverized fly ash (PFA) to create binding agents. Other methods include using steel slag and low-CO2 additives that can be combined with excavation materials to form cement-free concrete.
Pioneering Use in Seattle
Last year, C-Crete Technologies, one of the first companies to use cement-free concrete, implemented this groundbreaking material in a commercial building project in Seattle. This adaptive reuse development involved pouring approximately 60 tons of cement-free concrete into the foundations and shear walls of a 120-year-old historic brick building as part of a seismic retrofit.
Environmental and Performance Benefits
C-Crete Technologies claims their concrete is an environmentally friendly alternative to conventional Portland cement, emitting close to zero CO₂ during its manufacture and even absorbing CO₂ from the atmosphere over time. The concrete used in the Seattle project exhibited excellent flowability, was easily pumped, and achieved a loading strength of over 5,000 pounds per square inch (psi), surpassing the ASTM standard of about 4,000 psi for most residential, commercial, and infrastructure applications.
The cement-free concrete also meets other key industry standards, showing outstanding durability, such as resistance to freeze-thaw cycles, alkali-silica reactions, and chloride and acid penetrations. Additionally, it is compatible with conventional concrete admixtures, allowing for seamless integration into existing construction practices.
Industry Impact
“We are thrilled to introduce our cement-free concrete, a game-changer in sustainable construction,” said Rouzbeh Savary, PhD, founder and president of C-Crete. “Our binder is a drop-in replacement for Portland cement that drastically reduces carbon emissions. Given that our product meets industry standards and has cost-parity with conventional concrete, it opens up an entirely new era in construction.”
Donald Davies, owner of the Seattle building and chair of Building Transparency, a nonprofit focused on addressing embodied carbon’s role in climate change, expressed his enthusiasm: “As a developer, a structural engineer of 33 years, and a leader in low-carbon construction, I’m seeing many lower-carbon concretes being discussed. I’m seeing exciting advancements, but few are ready to scale into production the way C-Crete can now. No-cement, and low-carbon concrete isn’t just a pipe dream. It is real, it is now, and it works. This project proves it’s possible, today.”
Future Prospects
Portland cement is responsible for around 7 percent of global CO2 emissions. By replacing it with the new material, the construction industry can substantially reduce its environmental footprint. Each ton of C-Crete binder that replaces Portland cement prevents approximately one ton of CO2 emissions. Additionally, the product utilizes a suite of natural minerals and industrial by-products, ensuring an abundant feedstock.
C-Crete Technologies looks forward to collaborating with architects, designers, general contractors, ready-mix companies, building owners, and decision-makers for infrastructure projects to accelerate the adoption of its sustainable concrete, paving the way for a greener future in construction.