Concrete is the most massively produced material in the world by volume and the second most consumed material in the world, after water.*
The production of concrete continues to grow every year. Today, we produce 3x as much per capita than 40 years ago.*
Carbon emissions comes from the production of cement, which is the "glue" inside of concrete.
1 ton of cement makes 1 ton of CO2.*
Photo by Massimo Virgilio on Unsplash
Concrete has, by some accounts, done more for humanity that almost any other material ever invented. It is the foundation of modern development, putting roofs over the heads of billions, fortifying our defenses against natural disaster and providing a structure for healthcare, education, transport, energy and industry. And, it's been around since the dawn of human civilization. What makes concrete so useful?
Very high compression strength -- it can support the weight of a whole building.
A quick set time, meaning when you can pour it, it will set quickly so you can build faster.
Easy to work with - it can be mixed, transported and placed into its final position with ease.
Can be stamped, textured, colored, even molded into artwork, making it both beautiful and practical.
Fire-resistant, doesn't burn, and increases the safety of building inhabitants..
Crush Raw Materials
Limestone and clay are mined, crushed, and ground into a fine powder called raw meal.
Convert to Lime
The raw meal is heated in a preheater and kiln, where it undergoes a chemical reaction, releasing CO2 and forming calcium oxide (lime).
Form Clinker in the Kiln
The lime is sintered at up to 1,450°C into small gray nodules called clinker, the active ingredient in cement. Fossil fuels release more CO2.
Grind into Cement
Clinker is cooled, mixed with gypsum, ground into a fine powder (Portland cement), and mixed with aggregate, sand and water to make concrete.
The concrete industry is at a crossroads—and many are stepping up. Through global initiatives like the Concrete Sustainability Council and local innovation, the industry is developing new ways to make concrete that are more environmentally, socially, and economically responsible.
At the heart of these efforts is low-carbon concrete—a broad category of concrete mixes and technologies designed to dramatically reduce greenhouse gas (GHG) emissions compared to traditional Portland cement-based concrete.
Here are some of the most promising approaches already in use or in development:
Supplementary Cementitious Materials (SCMs): Incorporating materials like fly ash (a byproduct of coal power plants) and slag (from steel production) reduces the need for traditional cement and can significantly lower emissions.
Portland Limestone Cement (PLC): By blending limestone directly into the cement mix, PLC can cut emissions by approximately 10% compared to ordinary Portland Cement.
Carbon Capture, Utilization, and Storage (CCUS): Some companies inject captured CO₂ into the concrete during mixing, where it mineralizes and becomes permanently trapped—achieving over 50% GHG reduction in some cases.
Alternative Raw Materials (ARMs): Replacing carbon-intensive limestone with minerals like calcium silicate rock can cut emissions by 10–50%, depending on the process.
Alternative Clinkers and Cements: Some companies are rethinking cement entirely—developing non-Portland binders that use radically different chemistries. These offer up to 10% or more in emissions savings today, with potential for much greater reductions in the future.
Low-Carbon Fuels: Switching from fossil fuels to natural gas, waste-derived fuels, or biomass in cement kilns can reduce emissions by 10–50%, depending on the energy source and blend.
Together, these innovations represent a powerful shift toward a more sustainable concrete industry—and an opportunity to rethink even the smallest of infrastructure projects, like sidewalk repairs, as part of the climate solution.
The industry and government agencies have overlooked a key market: Us! Residents of San Jose can take meaningful climate action right in front of our homes.
Each repair delivers immediate carbon reduction, with an even greater ripple effect powered by consumer demand. Residents talk to their contractors, tell their landscapers and normalize low-carbon choices across the ecosystem.
That’s how markets shift—from the sidewalk up.
* Sources: World Economic Forum, International Energy Agency, Concrete Sustainability Council, Project Drawdown, and CarbonCure.