Researching casting green cement samples into molds to cure and later test their structural properties.
What if the key to greener concrete wasn’t mined from the Earth, but grown in the ocean?
Researchers from the University of Washington and Microsoft have developed a new type of low-carbon concrete using powdered seaweed.
By blending dried green algae with cement, the team created a formulation with 21 percent lower global warming potential while maintaining the material’s structural strength.
Their findings highlight how combining natural materials with machine learning tools can speed up the search for more sustainable building solutions.
Cement, the critical binding agent in concrete, is one of the world’s most polluting materials. It’s responsible for up to 10 percent of all global CO₂ emissions, largely from fossil fuel use and a carbon-releasing chemical process called calcination.
Producing one kilogram of cement emits nearly a kilogram of CO₂. In contrast, seaweed acts as a carbon sink while it grows, making it a promising alternative additive.
“Cement is everywhere — it’s the backbone of modern infrastructure — but it comes with a huge climate cost,” said senior author Eleftheria Roumeli, a UW assistant professor of materials science and engineering.
“What makes this work exciting is that we show how an abundant, photosynthetic material like green seaweed can be incorporated into cement to cut emissions, without the need for costly processing or sacrificing performance.”
Ordinarily, arriving at the right mix of ingredients would take years of trial and error, as each concrete sample needs weeks to cure before it can be tested.
To overcome that bottleneck, the team used a custom machine learning model that predicted optimal seaweed-cement blends. By feeding test results back into the system, they honed the formulation in just 28 days, a process Roumeli estimates would have otherwise taken five years.
“Machine learning was integral in helping us dramatically shorten the process — especially important here, because we’re introducing a completely new material into cement,” Roumeli said.
Unlike other cement additives that require complex treatments or manufacturing steps, green seaweed can be used in its dried, powdered form without costly processing.
This makes it a particularly accessible option for scaling low-carbon concrete production globally.
By pairing this natural material with machine learning, the researchers envision a system where producers can quickly develop customized cement formulations tailored to local resources and environmental conditions, whether that involves different algae species, food waste, or other bio-based additives.
The team now aims to explore how different seaweed compositions and structures influence cement performance.
Their broader goal is to expand the method to other algae varieties or even food waste, enabling producers worldwide to develop local, sustainable cement alternatives, with machine learning accelerating the optimization process.
“By combining natural materials like algae with modern data tools, we can localize production, reduce emissions, and move faster toward greener infrastructure,” Roumeli said.
“It’s an exciting step toward a new generation of sustainable building materials.”
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