Bioinspired Organic–Inorganic Hybrid Magnesium Oxychloride Cement via Chitosan and Tartaric Acid

The development of magnesium oxychloride cement (MOC) contributes to reducing CO2 emissions and recycling potash industrial wastes. Unfortunately, MOC is restricted by its water sensitivity, and fabrication of an MOC-based composite with combined water resistance and compressive strength is still challenging. Bioinspired by marine organisms, we herein proposed an organic–inorganic hybrid strategy to enable such a cementitious material. Under a sustainable development concept, we chose biobased chitosan (CS) and tartaric acid (TA) as organic components, which can provide more active sites for Mg2+ ions in MOC to construct the stable double chelating network, thus promoting the generation of phase 5. The MOC–CS–TA composite realized the combination of a high compressive strength (52.25, 59.01, and 61.52 MPa at various curing ages, respectively) and an enhanced water resistance coefficient (0.88) compared with other MOC-based materials. The improvement can be attributed to the physical filling and protective effects of gel-like phase 5 and chelating products, which is similar to reef-building oysters and slush-buried sea rocks. This work provides a workable guideline for the practical applications of eco-friendly and high-performance building materials.