Laying the Foundation for Low-Emission Cement and Concrete

Key Takeaways:

• Cement, the main building block of concrete, is responsible for about 8% of global carbon dioxide emissions.
• Limestone calcined clay cement, algae-based bio-cement, and carbon-negative cement from seawater are all innovative solutions that could help reduce emissions.
• Sustainable concrete provides economic benefits like lower maintenance and life-cycle costs, as well as higher durability. The global green concrete market is projected to grow from $39 billion in 2024 to $102 billion by 2032.

The most-used substance on Earth after water is concrete. In fact, the world produced over four billion metric tonnes of cement, the binder in concrete, in 2023 alone. Concrete fuels industrial growth as it provides the physical foundation of schools, hospitals, and other critical buildings, as well as transportation infrastructure. 

Concrete is formed by mixing aggregates (sand and gravel) with water and cement to bind the materials together. Portland cements are the most commonly used in the United States and are very energy-intensive. Both calcination itself (the chemical process triggered by heating limestone, which is part of the cement-making process) and the burning of fossil fuels to heat cement kilns emit carbon dioxide. Producing one kilogram of cement results in one kilogram of carbon dioxide entering the atmosphere. If the cement industry were a country, it would be the third-largest greenhouse gas emitter in the world. In total, cement is responsible for most of the carbon dioxide emissions associated with concrete and about 8% of carbon emissions globally. Mixing concrete releases additional greenhouse gases, including sulfur dioxide and nitrogen oxides, which can exacerbate local air pollution. 

Credit: Chicagoland Concrete, Inc. via Wikimedia Commons.

In 2019, the carbon intensity of U.S. cement production was around 20% higher than in the rest of the world, indicating a significant opportunity for domestic innovation in this space. One way to produce lower-carbon cement is to replace clinker, the main ingredient in cement, with supplementary cementitious materials. These materials are usually industrial byproducts like fly ash, slag cement, or silica fume. The American Cement Association plans to decrease its clinker-to-cement ratio using such alternatives, from its current average of 0.88 to 0.75 by 2050. The Global Cement and Concrete Association expects the global ratio will decrease from 0.76 to 0.52 by 2050.  

Some companies and universities are getting ever more creative in trying to develop low-emission cement. For example, limestone calcined clay cement is made from blended limestone and calcined clay. Other efforts are focused on bio-cement, which can be made from algae-grown limestone, while Northwestern University created a carbon-negative cement from seawater, electricity, and carbon dioxide. As for concrete, low-carbon alternatives include aerated concrete (or aircrete) made from air bubble chemical reactions, green concrete from discarded materials, and hempcrete from biocomposite materials. 

One barrier to innovation is the need to update codes and standards related to concrete. According to Abigail Regitsky of Blue Horizons Foundation, current concrete standards are largely prescriptive. “You can think of this like a recipe. You are told exactly how much water, how much cement, how much aggregate, and other things to mix into your concrete. That is really limiting to innovation of these new materials. And so there are efforts to change this from a prescriptive specification to performance specifications.” Performance-based standards, which would directly consider qualities like compressive strength and chloride permeability, would create a safe and uniform system for low-carbon concrete to be produced at scale. 

Using low-emission green concrete offers long-term economic benefits as durability increases, energy efficiency improves, and maintenance costs decrease. Qatar University researchers found that buildings made with a concrete mix consisting of treated wastewater, recycled concrete aggregates, and 20% fly ash saw maintenance costs decrease by 60% and life-cycle costs by 19% because the final material is stronger and less vulnerable to corrosion. The global green concrete market was valued at $39 billion in 2024, and its revenue is expected to reach nearly $102 billion by 2032. Switching to low-emission concrete can increase profits for builders by 3% to 21%. 

Technology companies are also making investments. Amazon Web Services uses low-carbon concrete from American Rock Products in its new U.S. data centers, while Meta has a similar data center partnership with CarbonBuilt. Central Concrete has partnered with CarbonCure to recycle carbon dioxide waste, which CarbonCure then injects into fresh concrete. 

In addition to material innovation, increasing energy efficiency is key to driving down emissions. Kiln operations can implement waste heat recovery systems, which capture and reuse waste heat from the kiln exhaust. Fuel switching is another promising strategy, though it can be challenging because cement ingredients are heated to over 2,500°F. Biomass, industrial waste, and hydrogen have potential as alternative fuel sources, and carbon capture and utilization technologies can be used to safely dispose of remaining carbon emissions. 

Congress has indicated interest in low-emission cement and concrete. Sens. Chris Coons (D-Del.), Thom Tillis (R-N.C.), Bill Cassidy (R-La.), and Alex Padilla (D-Calif.) introduced the Concrete and Asphalt Innovation Act (S.1067) in March 2025 to accelerate the use of low-emission concrete and asphalt. As Sen. Tillis explained, “the Concrete and Asphalt Innovation Act is a smart, bipartisan investment in America’s industrial future, and it will strengthen domestic manufacturing, create jobs, and reduce emissions.” Meanwhile, the House passed the Innovative Mitigation Partnerships for Asphalt and Concrete Technologies (IMPACT) Act (H.R.1534), which was reintroduced by Reps. Max Miller (R-Ohio) and Valerie Foushee (D-N.C.). This legislation would establish a temporary low-emission cement, concrete, and asphalt program at the U.S. Department of Energy. According to Rep. Foushee, “We have a critical opportunity to reinvigorate our nation’s transportation infrastructure while making significant strides to reduce global emissions.” Both pieces of legislation underscore that investing in low-emission cement will keep the United States globally competitive and encourage economic growth. 

With the global demand for concrete expected to increase 48% by 2050, the industry is ripe for investment to ensure that greenhouse gas emissions do not grow with it. Some companies are already finding ways to optimize concrete formulas and increase concrete recycling or material recovery. Sustainable concrete and cement production is a practical switch that can save money by building longer-lasting structures.

Author: Hailey Morris