Geologically-inspired calcium carbonate-based sustainable cementitious materials

During geological diagenesis, calcium carbonate (Cc) particles can aggregate and solidify into dense continuous structures. Inspired by this natural process, this study proposes a new low-carbon cementitious system, Cc cementitious materials, and aims to produce dense Cc pastes within timescales comparable to those of conventional manufacturing processes. To accurately clarify the mechanism behind, high-purity Cc polymorphs (amorphous calcium carbonate (ACC), vaterite, aragonite, and calcite) were used. Results show that the densification behaviour of Cc polymorphs was influenced by the particle rearrangement capability, dissolution–precipitation characteristics, and precipitated crystal morphologies. Among those polymorphs, the paste made from ACC exhibited excellent early-age mechanical properties and could obtain a compressive strength of 23 MPa with a mild cold-sintering process. The findings suggest the potential of Cc as a binder in cold-sintered construction materials, thus providing insights for developing a low or even negative carbon Cc-based concrete from calcium-rich solid wastes and atmospheric carbon dioxide.