Northwestern researchers have demonstrated a laboratory process that uses seawater, electricity and injected carbon dioxide to grow mineral solids with sand-like properties. The material may eventually serve as an aggregate or an ingredient in other construction products, but it is not an established commercial replacement for concrete sand.
How seawater becomes a sand-like solid
The process uses electrodes immersed in seawater. An electric current splits water, producing hydrogen gas and hydroxide ions. While current continues to flow, carbon dioxide is bubbled through the water, increasing the bicarbonate concentration. The hydroxide and bicarbonate react with calcium and magnesium ions already present in seawater, precipitating minerals including calcium carbonate and magnesium hydroxide.
In Northwestern Engineering’s March 19, 2025 report, the experimental solids are described as primarily calcium carbonate and/or magnesium hydroxide. The process does not produce one fixed material: researchers varied voltage and current, carbon dioxide flow, timing, duration and seawater recirculation. Depending on those conditions, the output could be flaky and porous or denser and harder; the team reports being able to control composition, size, shape and porosity.
What it could be used for—and what is not established
Northwestern proposes that the mineral material could substitute for sand or gravel in concrete, or potentially be used in cement, plaster and paint. These are suggested applications, not demonstrated commercial uses. The reviewed sources do not establish that this exact material is available to buy, has been used in concrete at field scale, or meets long-term concrete performance requirements.
#1 Best Overall
- FOR EASY REPAIRS — It's the ideal concrete patch repair mix, neatly fixing cracks and spalls so your property looks like new. It's even textured for a more seamless blend with the existing structure
- TOUGH AND DURABLE — Formulated to avoid shrinking or cracking, the ready-to-use premixed cement patch offers good adhesion and high strength so your slabs, walls & walkways/sidewalks perform as good as ever
- EASY CLEANUP — Sika concrete patch is acrylic-based, so once application is done, it cleans up using only water. No need for special cleaners and chemicals
- GREEN — It follows regulations concerning the use of volatile organic compounds (VOC), helping to keep the air we breathe cleaner and fresher
- A BREEZE TO USE — Minimal prep is required, since it comes premixed. Just use a putty or trowel to spread where repairs are needed. It takes only a few hours to set and about a day for a full cure
Northwestern notes that sand or gravel accounts for 60–70 percent of concrete. That figure is the university report’s description of concrete’s constituents; it does not mean the experimental material has replaced that share in any mix. For construction use, the material would need to satisfy the relevant requirements for particle properties and performance, and the available reporting does not provide field-scale validation or long-term concrete results.
How much CO₂ can the material store?
Northwestern’s example is a material composed of equal parts calcium carbonate and magnesium hydroxide. The university says one metric ton of that material could have capacity to store over one-half metric ton of CO₂. Capacity depends on the mineral ratio, so the figure should not be generalized to every possible output.
Rank #2
- QUICK SETTING: Sets in 20 minutes
- VERSATILE: Indoor, and outdoor use
- EASY TO USE: Ready to use! Just add water, mix, and use!
- MULTIPLE SURFACES: Handrails, bolts, poles, fixtures, and more
- PRACTICAL SIZE: 10 pound bag saves your back while providing plenty of cover
This is a reported storage capacity for an example composition, not a measured lifecycle removal rate or a guarantee of net climate benefit. The report does not provide a full lifecycle assessment accounting for electricity, carbon dioxide sourcing, processing and deployment. The process also releases hydrogen, described by the university as a potentially useful coproduct; the report does not establish its commercial yield, cost or lifecycle emissions.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Scale-up and what happens to the water
Study lead Alessandro Rotta Loria envisions modular reactors that would run in controlled equipment rather than directly in the ocean. In the proposed approach, operators would control input-water and effluent chemistry, then return effluent to open seawater only after adequate treatment and environmental verification. This is a deployment concept, not evidence that field-scale environmental validation or deployment has been completed.
Recommended Free Tools
Rank #3
- Quikrete #110110 10LB Concrete Mix
- QUIKRETE COMPANIES
Commercial performance remains unestablished for this specific material: the available sources do not report field-scale production, industrial operating performance, lifecycle emissions or commercial availability. A broader 2026 American Chemical Society perspective discusses seawater electrolysis as a route relevant to carbon removal, renewable hydrogen and cement and concrete decarbonization, but it does not establish commercial readiness for Northwestern’s particular sand-like solids.
Quick Recap
Best Value
- This item Rockite expansion cement 15 min 1 lb
- Used for hardware, glue
- The product is manufactured in United States
- Model number: 10001
Rank #4
- This product adds a great value
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
