This study describes and demonstrates a carbon-negative process for manufacturing cement from widely abundant seawater-derived magnesium (Mg) feedstocks. In contrast to conventional Portland cement, which starts with carbon-containing limestone as the source material, the proposed process uses membrane-free electrolyzers to facilitate the conversion of carbon-free magnesium ions (Mg2+) in seawater into magnesium hydroxide (Mg(OH)2) precursors for the production of Mg-based cement. After a low-temperature carbonation curing step converts Mg(OH)2 into magnesium carbonates through reaction with carbon dioxide (CO2), the resulting Mg-based binders can exhibit compressive strength comparable to that achieved by Portland cement after curing for only two days. Although the proposed “cement-from-seawater” process requires similar energy use per ton of cement as existing processes, its potential to achieve a carbon-negative footprint makes it highly attractive to decarbonize one of the most carbon intensive industries.

About 2 000 000 billion litres of water is consumed globally every year. The amount of potable water available is reducing due to pollution of various water bodies. The textile industry waste water is one of the sources of pollution. There are problems associated with handling dye waste water, with the treatment process, and with several environmental problems that also occur. On the other hand, about 700 million litres of potable water is used for the production of concrete. Using the waste dye water in concrete reduces the overall water consumption and at the same time it provides a solution to the dye waste water disposal problem, making it beneficial in socioeconomic as well as environmental terms. This study explored the possibility of 100% replacement of potable water with textile dye waste water in cement concrete. The preliminary study indicated that the fresh and hardened properties of concrete made using potable water and textile dye waste water (untreated water) are comparable.

This study describes and demonstrates key steps in a carbon-negative process for manufacturing cement from widely abundant seawater-derived magnesium (Mg) feedstocks. In contrast to conventional Portland cement, which starts with carbon-containing limestone as the source material, the proposed process uses membrane-free electrolyzers to facilitate the conversion of carbon-free magnesium ions (Mg 2+ ) in seawater into magnesium hydroxide [Mg(OH) 2 ] precursors for the production of Mg-based cement. After a low-temperature carbonation curing step converts Mg(OH) 2 into magnesium carbonates through reaction with carbon dioxide (CO 2 ), the resulting Mg-based binders can exhibit compressive strength comparable to that achieved by Portland cement after curing for only 2 days. Although the proposed “cement-from-seawater” process requires similar energy use per ton of cement as existing processes and is not currently suitable for use in conventional reinforced concrete, its potential to achieve a carbon-negative footprint makes it highly attractive to help decarbonize one of the most carbon-intensive industries.

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This study describes and demonstrates a carbon-negative process for manufacturing cement from widely abundant seawater-derived magnesium (Mg) feedstocks. In contrast to conventional Portland cement, which starts with carbon-containing limestone as the source material, the proposed process uses membrane-free electrolyzers to facilitate the conversion of carbon-free magnesium ions (Mg2+) in seawater into magnesium hydroxide (Mg(OH)2) precursors for the production of Mg-based cement. After a low-temperature carbonation curing step converts Mg(OH)2 into magnesium carbonates through reaction with carbon dioxide (CO2), the resulting Mg-based binders can exhibit compressive strength comparable to that achieved by Portland cement after curing for only two days. Although the proposed “cement-from-seawater” process requires similar energy use per ton of cement as existing processes, its potential to achieve a carbon-negative footprint makes it highly attractive to decarbonize one of the most carbon intensive industries.