ChemRxiv, vol.1, pp.1-39, 2021 (Non Peer-Reviewed Journal)
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.