Bioinspired calcium carbonate binders via synergistic crystallization control of amorphous calcium carbonate using poly aspartic acid and magnesium ions

Inspired by the biomineralization process, amorphous calcium carbonate (ACC) can be served as a precursor for fabricating calcium carbonate based cementitious materials. This study presents a biomimetic approach to prepare a novel calcium carbonate binder through controlled ACC crystallization using poly aspartic acid (pAsp) and magnesium ions (Mg²⁺) as an organic-inorganic binary system. The results indicate that the pAsp-Mg²⁺ binary additives substantially improve ACC stability, prolonging its lifetime from 1 day to 3 days. This extended stabilization enables controlled crystallization of ACC characterized by the formation of fibrous crystals (at 3 days), followed by vaterite and Mg-calcite phases (at 7–14 days) with progressive crystal refinement. Compared to unmodified systems, the modified CaCO₃ binder achieves a 107.65 % increase in compressive strength alongside improved microscale mechanical properties and reduced porosity. This study establishes a biomimetic route to designing calcium carbonate-based cementitious materials through modifying ACC crystallization kinetics using synergistic organic–inorganic modifiers. This finding demonstrates the potential of calcium carbonate as a sustainable binder, which provides a promising pathway to develop low-carbon or even carbon-negative concrete.