High-Performance CO2 Sequestration Solid Materials Consist of β-C2S and γ-C2S Binary Clinkers Synthesized from Carbide Slag and Sandstone: Sintering, Carbonation, and Microstructure

In this work, we propose low-energy consumption and high-performance CO2 sequestration solid materials consisting of β-C2S (dicalcium silicate) and γ-C2S binary clinkers synthesized by using carbide slag, sandstone, and ferroferric oxide (Fe3O4). The performance controlling factors for carbonated compacts were investigated and found that the C2S clinker composition was the key factor. The presence of a small (i.e., 5.2%) amount of β-C2S in the mixture could reduce the first-stage activation energy during the carbonation reaction compared to that of powder (i.e., basically γ-C2S), thus accelerating the whole carbonation reaction. The compressive strength of carbonated compacts made from the mixture was nearly 2.5 times that of carbonated compacts made from powder (i.e., 116.8 and 47.4 MPa, respectively) after 24 h of CO2 curing. The 24 h degree of carbonation of carbonated compacts made from the mixture was nearly 1.5 times that of carbonated compacts made from powder (i.e., 45.0 and 30.2%, respectively). This finding could provide guidance on the high-performance CO2 sequestration solid materials from the view of adjustment of the proportion of β-C2S and γ-C2S in C2S binary clinkers by a one-step sintering reaction.