Seaweed‑Infused Cement: A Greener Future for Construction

Concrete is the silent titan of infrastructure, forming the backbone of cities, homes, highways, and even the digital backbone of our economy—data centers. Its core ingredient, cement, is so pervasive that it is surpassed in human consumption only by water. Yet, this structural ubiquity has a dark side: nearly 8–10% of global carbon dioxide emissions are the direct result of the energy-intensive, fossil-fueled chemistry necessary to produce one of the world’s most basic building materials. As the world races to mitigate climate change, the construction industry has been placed firmly under the spotlight, spurring an urgent search for scalable, effective, and cost-competitive alternatives.

Amidst this global scramble, an unexpected hero has emerged from the ocean: seaweed. Once regarded as little more than beach detritus or a sushi staple, seaweed—specifically, certain macroalgae—has stepped into the limelight as a transformative, eco-friendly additive for cement. This article explores the fascinating journey of seaweed-infused cement: its scientific origins, the people and ideas that drove its development, environmental benefits, future horizons, and how it stands alongside—and in competition with—other bio-based and novel low-carbon building materials.

Inspiration from the Sea: The Origins of Seaweed-Infused Cement

The idea of incorporating seaweed into cement blends might sound whimsical, but it’s rooted in a serious quest to decarbonize construction at the molecular level. The pathway began with recognizing a fundamental paradox. On the one hand, cement production is tightly linked to climate change due to prodigious CO₂ emissions. On the other, seaweed represents one of the planet’s most efficient carbon sinks, drawing CO₂ from the atmosphere as it photosynthesizes and storing it within robust, mineral-rich tissues.

The concept of using seaweed in construction wasn’t entirely new: cultures along coastal regions have made use of dried algae in plasters, binding agents, and even as insulation for centuries. However, it’s only in the last decade—against the backdrop of climate activism and green tech innovation—that scientific curiosity focused on whether macroalgae could, with modern materials science, become a true structural additive for cement that improved both its environmental and engineering profile.

A critical leap happened as researchers from material, environmental, and marine sciences began to see seaweed’s unique blend of rapid renewability, mineral wealth (particularly calcium and silica), and carbon fixation as more than just ecological curiosities. The hypothesis: if dried and powdered seaweed could partially replace the cement binder in concrete, perhaps its addition could provide comparable performance with a fraction of the carbon footprint.

Pioneers and Innovators: The Teams Changing the Game

At the heart of the recent surge in seaweed-infused cement research is the multidisciplinary team led by Dr. Eleftheria Roumeli, assistant professor of materials science and engineering at the University of Washington, collaborating with Microsoft Research’s Dr. Kristen Severson, UW doctoral candidate Meng-Yen Lin, and former postdoc Paul Grandgeorge. Their work is emblematic of the 21st-century approach to scientific discovery: blending traditional experimental chemistry and engineering with state-of-the-art artificial intelligence.

The Roumeli team, inspired by the challenge of tackling concrete’s carbon problem at its chemical source, focused on green seaweed—specifically Ulva species, known for their rapid growth rates and robust cell structure. Previous efforts with microalgae had shown promise but were hampered by lower replacement rates and performance issues. Ulva’s larger structure offered the promise of improved reinforcement and compatibility within cementitious systems.

Crucially, the team understood that developing a new cement blend was no trivial matter: waiting 28 days or more for each set of concrete samples to cure and be tested for strength and durability made traditional trial-and-error experimentation prohibitively slow. Enter Microsoft’s expertise in machine learning. By training an AI model to predict and optimize the performance of different seaweed-cement blends, they were able to accelerate discovery, compressing what could have been a five-year research cycle into a single month. This synergy of humans and algorithms was pivotal in finding a recipe that reduced global warming potential by 21%—without any sacrifice in compressive strength or processability.

The Science of Seaweed Cement: How and Why It Works

Chemistry and Material Performance

Seaweed is a complex plant, rich in minerals, polysaccharides, and structural components that can enhance the matrix of concrete. When dried and powdered, it can be incorporated into cement mixtures at levels up to 5% by weight. In Roumeli’s research, incorporating Ulva seaweed yielded a number of positive outcomes:

Reduced Carbon Footprint: As seaweed grows, it absorbs CO₂, functioning as a carbon sink. Using seaweed in cement not only replaces part of the emissions-heavy cement, but also “locks in” biogenic carbon for the lifetime of the concrete.
Maintained or Enhanced Strength: Despite concerns that biomaterial additives might degrade mechanical performance, tests showed that seaweed partial replacement meets or even slightly exceeds standard compressive strength benchmarks.
Durability and Processability: Seaweed’s mineral profile and microstructure impart durability and help maintain water retention, which is key for the proper curing and long-term integrity of concrete.

Machine Learning in Materials Optimization

One of the most innovative aspects of this research is the use of machine learning (ML) to optimize formulations rapidly. By training a model on an initial set of 24 formulations—including different ratios of water, cement, aggregate, and seaweed—the researchers could predict the final performance of new recipes without waiting for the full curing period. This feedback loop, known as closed-loop optimization, enabled them to iterate quickly, identifying mixes with the highest performance and lowest environmental impact.

This approach not only sped up discovery but created a framework that is adaptable by geography and local resources. With ML, regional producers could train new models using their own locally-available algae species, minerals, or even food/agricultural waste—customizing eco-cement recipes to suit local conditions.

Seaweed Types, Sargassum Aggregates, and Global Adaptability

The most prominent seaweed used so far in structural cement applications is Ulva, a green macroalga abundant in temperate and tropical coastal waters. Its fast growth, high mineral content, and structural bulk make it ideal for scalable applications.

Yet, innovation has also arisen from necessity: Sargassum, a troublesome brown macroalga notorious for washing up in massive, smelly mats on Caribbean beaches, has been repurposed as an aggregate for clay bricks and even as filler or binder in eco-blocks. Researchers in Brazil and the Caribbean have demonstrated that sargassum can be integrated into lightweight ceramic aggregates, fiber cement tiles, and panels, sometimes even replacing 100% of the limestone with sargassum ash in certain products.

This flexibility opens the door to a localization model for green cement: tropical regions with sargassum, temperate zones with Ulva or other native macroalgae—each adapting their recipes to local circumstances, supporting circular economies, and reducing both waste and transport emissions.

Environmental Impact: Quantifying the Benefits

Carbon Footprint Reduction

Perhaps the single strongest argument for seaweed-infused concrete is the dramatic reduction in carbon emissions. At 5% seaweed inclusion, the global warming potential is reduced by 21% compared to traditional 100% cement-based binders. This is a substantial cut, given that cement’s global emissions rival those of all transportation combined.

Carbon Sequestration and Circular Benefits

Carbon Storage: Seaweed absorbs atmospheric CO₂ as it grows; when incorporated into concrete, this carbon is sequestered for the entire lifecycle of the material—often many decades, at minimum.
Local, Renewable Resource: Compared to mined minerals, seaweed regrows rapidly, often in just a few weeks or months, and can be cultivated on marginal or oceanic lands with minimal freshwater or fertilizer input.
Waste Remediation: Using seaweed like sargassum not only creates a market for algae that would otherwise be landfilled or incinerated, but also helps remediate environmental crises (e.g., Caribbean beach fouling).

Energy and Resource Efficiency

Seaweed harvesting, drying, and powdering require less energy than quarrying and processing cement or aggregate. Seaweed can be cultivated in Integrated Multi-Trophic Aquaculture (IMTA) systems, further reducing the environmental footprint of oceanic farming.

From Lab to Site: Applications and Commercialization Pathways

Current and Potential Uses

Structural Concrete: Both the University of Washington and pilot initiatives in India and Brazil have shown that seaweed can be used as a direct partial substitute in cast-in-place and precast concrete for buildings and infrastructure.
Eco-Friendly Bricks: In the Caribbean, Sargablocks—made with up to 40% sargassum seaweed, the rest being limestone and other organics—have already been used to build affordable homes, showcasing resilience to hurricanes and tropical storms.
Panels and Tiles: Sargassum has proven effective in lightweight panels for construction and fiber-cement tiles, even replacing limestone with seaweed ash in some cases, meeting current standards and improving durability.

Material Performance and Scalability

Research demonstrates that, at optimal dosages (usually 5–10% by mass), seaweed additives do not diminish, and may even enhance, compressive and tensile strength; they can also improve moisture retention, internal curing, and shrinkage characteristics. For Sargablock and similar innovations, field tests confirm the material’s resistance to tropical conditions and longevity far beyond what might be expected for a waste-based product.

The true promise, however, lies in scalability. Seaweed is abundant, renewable, and globally distributed, with oceanic “farming” potential measured in tens of millions of tons per year, posing no competition to food supplies and requiring no arable land. This could enable not just niche sustainable design but mainstream adoption—if economic and regulatory hurdles are met.

Regulation, Standards, and Barriers to Adoption

Regulatory Pathways

Cement and concrete are among the most strictly regulated of all materials, due to their underpinning role in public safety. Any new additive must pass rigorous testing for:

Structural Strength and Durability
Fire and Moisture Resistance
Consistency Over Large Batches
Compatibility with Existing Construction Methods

The pioneering University of Washington seaweed cement passed industry-standard compressive strength tests, positioning it well for further code adoption efforts. In Mexico, Sargablock homes have likewise been accepted for low-income housing, with planned expansion into other parts of Latin America and even the United States.

Standardization Efforts

Efforts are underway internationally to expand relevant standards (such as EN 197-1 and EN 197-5 in Europe, ASTM standards in the US, and others globally) to cover novel low-carbon and bio-based cementitious systems. As demonstrated in studies on machine-learning optimized green cements, there is a call for regulatory frameworks that accommodate multi-component blends and regionally variable raw materials.

Barriers: Knowledge, Acceptance, and Scale

Despite compelling data, many industry players remain cautious—for reasons ranging from perception of risk, warranty concerns, cost, to simple inertia. Demonstration projects, accelerated performance validation, and broader consumer education will be pivotal in closing this gap. Concomitantly, scaling up cultivation and industrial processing of seaweed for construction, with reliable supply chains, remains a work in progress.

Beyond Seaweed: Complementary and Competitive Eco-Friendly Materials

While seaweed-infused cement represents a major breakthrough, it is part of a fast-expanding ecosystem of green building materials, each with strengths and limitations, and in many cases, synergies with seaweed-based approaches.

Straw-Based Bio-Composites

Straw, a by-product of agriculture, is being transformed into high-performance prefabricated panels, acoustic boards, and insulating blocks. Companies like EcoCocon and New Frameworks produce straw panels with negative embodied CO₂ values and high renewable content—sequestering more carbon than they emit. These panels can be used for wall systems, insulation, or as a component in hybrid concrete assemblies.

Hemp-Based Building Materials

Hemp is another champion of bio-based construction. With rapid growth, high carbon sequestration, and robust fiber properties, hemp is being used for:

Hempcrete: A mixture of hemp hurds, lime, and water, offering high insulation and carbon storage.
Hemp-clay boards and hemp particleboard: Strong, lightweight, recyclable, with low embodied energy and VOC emission.

Mycelium-Based Materials

The fungal root system, mycelium, has now moved from concept to reality as a grown-in-place building material. Mycelium can be cultivated in molds with agricultural waste, forming bricks, insulation panels, and even complete wall systems with excellent fire resistance, thermal/acoustic properties, and full biodegradability at end-of-life.

Biochar-Infused Cement

Biochar—a form of carbon-rich material derived from pyrolyzed biomass—has tremendous promise as a supplementary cementitious material. Studies confirm that replacing 1–2% of cement with biochar can slightly enhance compressive strength, improve durability, act as an internal curing agent, and, significantly, sequester carbon within the cement matrix. Combining seaweed with biochar could further amplify sustainability benefits.

Other Bio- and Tech-Enhanced Innovations

AggreCrete and Polymer-Modified Concrete: Hydrophobic, low-permeability, and recyclable alternatives, especially for marine or flood-prone environments.
Graphene-Enhanced Cement: Nanomaterial additives like graphene or nano-cellulose for strength without mass, sometimes offering routes for incorporating algal or plant-based matter.

The table below summarizes key properties, advantages, and challenges of several eco-friendly alternatives, including seaweed-infused cement:

Material Type	Main Resource/Input	CO₂ Reduction Potential	Performance (Structural)	Key Advantages	Challenges
Seaweed-Infused Cement	Ulva, Sargassum, etc.	~21% (or more)	Comparable to standard cement	Fast renewability, carbon sink, scalability	Supply chain for mass production, full life-cycle/LCA validation
Straw Panels/Bio-composites	Wheat, rye, rice straw	Up to -95% (negative)	Good (for insulation, walls)	Carbon-negative, insulation, acoustic	Moisture protection, integration with structure
Hempcrete & Hemp Boards	Industrial hemp	High	Insulation, non-structural	Rapid regrowth, carbon store, versatile	Regulatory barriers, limited structural use
Mycelium-Based Materials	Fungal mycelium + waste	High	Insulating, some bricks	Fully biodegradable, fire resistance, custom shapes	Scaling up, structural limitations
Biochar-Infused Cement	Pyrolyzed biomass	High, even carbon-negative	Strong at low doses, durable	Internal curing, improved durability, waste valorization	Variability in properties, cost, standardization
Sargassum Clay Aggregates	Sargassum + clay/ash	High LCA improv.	Panels, blocks, tiles	Waste-to-resource, lighter weight, local solution	Consistency, salt/mineral impact

Looking Ahead: Future Possibilities for Seaweed-Based and Bio-Based Construction

Scaling, Ecosystem Integration, and Dynamic Blending

Global Adaptability: As machine learning–assisted optimization becomes the norm, local blending of available biomaterials (including seaweed, biochar, straw, and hemp) could create region-specific, high-performance eco-concretes.
Decentralized, Localized Manufacturing: Empowering small- and medium-sized producers, including in the Global South and Small Island States, to utilize their own “waste” resources could revolutionize construction supply chains.
Hybrid Systems: Combining different eco-materials (e.g., seaweed cement panels with biochar aggregate, hemp-bio panels, or mycelium-insulated walls) enables entire buildings to achieve net-zero or net-negative embodied carbon.

Environmental and Societal Impact

Circular Economy: Utilizing fast-growing marine and agricultural by-products in construction addresses both environmental pollution (e.g., sargassum beach crises) and resource depletion.
Community Resilience: In disaster-prone or low-income areas, access to cheaper, more durable, climate-resilient housing built from local seaweed or biomaterials bolsters recovery efforts and lowers systemic risk.

Remaining Barriers and Research Frontiers

Life-Cycle and End-of-Life Analytics: More long-term LCA data and standardized testing on seaweed/bio-blended concretes are needed.
Building Code Evolution: Ongoing advocacy to update local and international building codes for the safe, performance-based adoption of novel biomaterials.
Supply and Cultivation: As demand grows for both food- and construction-grade seaweed and other bioproducts, sustainable aquaculture and harvesting practices are paramount.
Economic Viability: Continued reduction in processing costs, scale economies, and value recognition (including carbon credit markets) will drive mainstream adoption.

The Road to a Greener Skyline: A Blueprint for Change

Seaweed-infused cement is much more than a clever hack; it is emblematic of an epochal shift in materials science—where biology, AI, and sustainability coalesce to reshape even the most familiar matter beneath our feet. The scale of opportunity is enormous: every kilogram of biogenic additive in cement is a kilogram of emissions foregone, a gram of oceanic waste repurposed, a step toward a regenerative built environment.

As the research matures, and as the construction sector embraces machine learning–optimized, multi-material formulations, the promise is clear: cities that store carbon instead of spewing it, buildings that give back rather than take, and a built environment in harmony with the planet’s cycles.

On beaches from the Caribbean to the Pacific Northwest, seaweed’s tale is shifting—from nuisance to necessity, from symbol of decay to foundation of renewal.

References

” The Secret Ingredient from the Ocean That Could Fix Cement’s Dirty Problem.” Science News Today, The Science Desk, 21 July 2025.
Poor, William. “Seaweed-Infused Cement Could Cut Concrete’s Carbon Footprint.” UW News, University of Washington, 17 July 2025.
Stiffler, Lisa. “UW and Microsoft Use Seaweed to Create Novel Carbon-Trapping Cement.” GeekWire, 8 July 2025.
Coffee, Calvin. “Microsoft-backed Scientists Develop Unbelievable Substance That Could Transform Construction Industry.” The Cool Down, 5 Sept. 2025.
Malewar, Pranjal. “Sargassum Seaweed Transforms into Eco-Friendly Building Blocks.” New Atlas, 5 Sept. 2025.
Breschi, Tommaso. “50 Sustainable Construction Materials to Watch in 2025.” Revalu Journal, 20 Jan. 2025.
“Hydration Kinetics of Biochar-Enhanced Cement Composites: A Mini-Review.” Buildings, vol. 15, no. 14, MDPI, 18 July 2025.
“Adding Biochar to Cement Yields Concrete That’s Stronger, More Environmentally Friendly.” TechXplore, University of Saskatchewan, 21 Aug. 2025.
“Machine Learning-Accelerated Discovery of Green Cement Recipes.” Materials and Structures, Springer, 17 June 2025.
“Sargablock | for Tomorrow.” United Nations Development Programme Mexico, 2020.
“Mr. Sargassum Has Built 13 Homes with Blocks Made of Seaweed.” Mexico News Daily, 20 July 2022.
“Building a Sustainable Future: Macroalgae in Green Concrete.” Blue Evolution, 2025.
Jacques, Kiley. “Compressed Straw Panels for Low-Carbon Building.” GreenBuildingAdvisor, 18 Apr. 2022.
“EcoCocon Pre-fabricated Straw Panel System.” Go Green Home Supply, 2025.
“Panels — New Frameworks.” NewFrameworks.com, 2025.
“Hemplith® 30 Lightweight Panel.” Von Hanf, 2025.
“Hemp-Based Fiberboard Moves Closer to Mass Market.” HempBuild Magazine, 4 Aug. 2025.
“How Mushrooms Are Being Used to Build Houses with Mycelium Blocks.” Longevity Botanicals, 16 May 2025.
Nasir, Osama. “From Fungi to Foundations: Mycelium in Construction.” Parametric Architecture, 2 July 2024.
“Living Mycelium in Sustainable Construction Materials: A Fungal Revolution.” ArchUp, 7 June 2025.
“Our Technology – ECOncrete.” econcretetech.com, 2025.
Kaminer, Riley. “Turning Sargassum into Concrete? It’s Possible, and It’s Oh-So-Eco, Thanks to Admix Innovations.” Refresh Miami, 18 Nov. 2024.
Wu, Fufei, et al. “Biochar Modification Enhances Mechanical and Durability Properties of Cement-Based Materials.” Nature Scientific Reports, 2025.
Ooi, M.K., and Mansor, M.F. “The Mechanical and Durability Properties of Cement Paste Containing Macroalgae Powder As Partial Cement Replacement.” Construction and Building Materials, vol. 274, 2021.
“Study on Strength of Concrete Prepared by Replacing Cement with Seaweed Powder.” International Journal of Advanced Engineering and Management, 2022.
Schmelzer, Ron. “AI-Engineered Cement Formulations Promise To Cut CO₂ Emissions In Half.” Forbes, 20 June 2025.
“Machine Learning-Accelerated Discovery of Green Cement Recipes.” Science Daily, Paul Scherrer Institute, 19 June 2025.
Poor, William. “Seaweed-Infused Cement Could Cut Concrete’s Carbon Footprint.” UW News, University of Washington, 17 July 2025.
“The Impact of Salt Water on Concrete vs. AggreCrete PMC.” AggreBind, 27 Nov. 2024.
“Biochar Cement Concrete Toward Decarbonisation and Sustainability for Construction: Characteristic, Performance and Perspective.” Nature Scientific Reports, 2023.
“Concrete Goes Blue: How Seaweed and AI Are Cracking Cement’s Dirtiest Secret.” ImpactLab, 19 July 2025.
“ECOncrete Technology.” ECOncrete, 2025.
“Mycelium in Construction Materials: Sustainable Building Solutions.” ArchUp, 7 June 2025.
Ashik, K.H., et al. “Study on Strength of Concrete Prepared by Replacing Cement with Seaweed Powder.” International Journal of Advanced Engineering and Management, 2022.
Malewar, Pranjal. “Sargassum Seaweed Transforms into Eco-Friendly Building Blocks.” New Atlas, 5 Sept. 2025.
Schmelzer, Ron. “AI-Engineered Cement Formulations Promise To Cut CO₂ Emissions In Half.” Forbes, 20 June 2025.
“The AI that Writes Climate-Friendly Cement Recipes in Seconds.” ScienceDaily, Paul Scherrer Institute, 19 June 2025.
“Virginia Uniform Statewide Building Code (USBC).” DHCD Virginia, 2025.
Kaminer, Riley. “Turning Sargassum into Concrete? It’s Possible, and It’s Oh-So-Eco.” Refresh Miami, 18 Nov. 2024.
“Biochar Modification Enhances Mechanical and Durability Properties of Cement-Based Materials.” Nature Scientific Reports, 2025.
“Living Mycelium in Sustainable Construction Materials: A Fungal Revolution.” ArchUp, 7 June 2025.
Poor, William. “Seaweed-Infused Cement Could Cut Concrete’s Carbon Footprint.” UW News, University of Washington, 17 July 2025.
“Panels — New Frameworks.” NewFrameworks.com, 2025.
“EcoCocon Pre-fabricated Straw Panel System.” Go Green Home Supply, 2025.
Jacques, Kiley. “Compressed Straw Panels for Low-Carbon Building.” GreenBuildingAdvisor, 18 Apr. 2022.
“UKU Hemp-light Clay Boards.” UKU, 2025.
“HEMPLITH® 30 Lightweight Panel.” Von Hanf, 2025.
“Hemp-Based Fiberboard Moves Closer to Mass Market.” HempBuild Magazine, 4 Aug. 2025.
“How Mushrooms Are Being Used to Build Houses with Mycelium Blocks.” Longevity Botanicals, 16 May 2025.
Nasir, Osama. “From Fungi to Foundations: Mycelium in Construction.” Parametric Architecture, 2 July 2024.
“Living Mycelium in Sustainable Construction Materials: A Fungal Revolution.” ArchUp, 7 June 2025.
“Adding Biochar to Cement Yields Concrete That’s Stronger, More Environmentally Friendly.” TechXplore, University of Saskatchewan, 21 Aug. 2025.
“Hydration Kinetics of Biochar-Enhanced Cement Composites: A Mini-Review.” Buildings, vol. 15, no. 14, MDPI, 18 July 2025.
Wu, Fufei, et al. “Biochar Modification Enhances Mechanical and Durability Properties of Cement-Based Materials.” Nature Scientific Reports, 2025.
Malewar, Pranjal. “Sargassum Seaweed Transforms into Eco-Friendly Building Blocks.” New Atlas, 5 Sept. 2025.
“Sargablock | for Tomorrow.” United Nations Development Programme Mexico, 2020.
“Mr. Sargassum Has Built 13 Homes with Blocks Made of Seaweed.” Mexico News Daily, 20 July 2022.

This work reflects a rigorous synthesis of current literature, diverse case studies, and cutting-edge research, aiming to offer Infinity Gent readers an authoritative, future-focused perspective on the promise and practicality of seaweed-infused cement and allied bio-based construction materials.

Get Stories That Match Your Curiosity

Subscribe to the Infinity Gent newsletter and choose the categories that inspire you most.

Infinity Gent