Humanity burns through roughly 30 billion metric tons of concrete every single year.
The Hidden Carbon Footprint Beneath Our Feet
Producing concrete accounts for roughly 8 percent of global human-generated carbon dioxide emissions. When factoring in the broader manufacturing of materials that compose the built environment, that figure climbs to about 15 percent, excluding the physical construction process itself. Cement, the chemical binder that holds concrete together, remains the primary driver of these emissions.
Despite these daunting statistics, proven technological tools exist around the world that could slash concrete-related emissions by approximately three-quarters. Sabbie Miller, a professor at the University of California, Davis, a faculty scientist at Lawrence Berkeley National Laboratory, and faculty director of the Materials Decarbonization and Sustainability Center, outlined these solutions during the Energy Solutions Forum this month.
Global Best Practices Left Off the Table
Miller’s research team at UC Davis tested the hypothetical impact of every country adopting the most efficient practices already proven elsewhere. The findings reveal a clear roadmap. Cleaner and more efficient kilns would cut concrete emissions by about 20 percent by the year 2100. Meanwhile, utilizing better-graded aggregates alongside a wider adoption of supplementary materials would trim emissions by over 30 percent.
Choosing stronger, more durable materials while remaining within existing building codes yields an additional 10 percent reduction. Stacked together, these three stages achieve a roughly 75 percent drop in greenhouse gas emissions from concrete. Crucially, this projection relies entirely on scaling existing technology rather than waiting for future breakthroughs.
“There are strategies already out there,” Miller said. “We just might not be implementing them to the fullest extent yet.”
Christopher Barile, the chemistry professor coordinating the forum, highlighted the urgency of addressing industrial materials. While public discourse frequently centers on fossil fuels burned by automobiles and airplanes, industrial materials represent a significant fraction of greenhouse gases, with concrete leading the sector and steel likely ranking second.
Regional Disconnects and Economic Roadblocks
Reaching absolute zero emissions by 2050 remains an elusive target through efficiency alone. Concrete can never be entirely cement-free because a binder is required to hold the aggregate matrix together. However, regional disparities in mixing standards demonstrate missed opportunities for immediate optimization.
Most of the world mixes concrete using two sizes of crushed rock, creating interstitial gaps that require heavy volumes of cement paste to fill. Canada utilizes three sizes, while Brazil employs four on numerous projects. When addressing why the United States remains tethered to two sizes, Miller noted the persistent hesitation.
Economic barriers further complicate implementation. While certain sustainable strategies are already cheaper than traditional methods, others remain financially unviable without government subsidies through carbon credits. Material reuse presents a prime example of economic friction. A recent California study demonstrated that repurposing industrial buildings into housing could cut 40 percent of the state’s anticipated emissions from housing. Yet, the barrier persists around structural ownership and split incentives.
Miller explained that the hurdles of building reuse involve the fact that the parties who own the structure, those who use it, and those who benefit from not replacing it are often different entities.
Beyond standard mixtures and reuse, speculative approaches explore utilizing the built environment as a long-term carbon sink. Integrating captured carbon dioxide into cements that harden through absorption, alongside synthetic aggregates, biochar, and timber, could theoretically meet the aggressive carbon storage targets established by the Intergovernmental Panel on Climate Change.
The Energy Solutions Forum will conclude its fall semester on Nov. 18 at 4 p.m. with an address by Taylor Wilson, applied nuclear physicist and founder of Prometheus Industries and Talos Materials, focusing on the future of nuclear energy technologies.
