Carbonation of a Synthetic CAF Compound by CO Absorption and Its Effect on Cement Matrix.

In the field of construction materials, the development of fundamental technologies to reduce energy consumption and CO emissions, such as manufacturing process improvement and the expanded use of alternative materials, is required. Technologies for effectively reducing energy consumption and improving CO absorption and reduction that can meet domestic greenhouse gas reduction targets are also required. In this study, calcium-aluminate-ferrite (CAF), a ternary system of CaO·AlO·FeO, was sintered at a low temperature (1100 °C) to examine the possibility of CO adsorption, and excellent CO absorption performance was confirmed, as the calcite content was found to be 11.01% after 3 h of the reaction between synthetic CAF (SCAF) and CO. In addition, the physical and carbonation characteristics were investigated with respect to the SCAF substitution rate for cement (10%, 30%, 50%, 70%, and 100%). It was found that SCAF 10% developed a compressive strength similar to that of ordinary Portland cement (OPC 100%), but the compressive strength tended to decrease as the SCAF substitution rate increased. An increase in the SCAF substitution rate led to the rapid penetration of CO, and carbonation was observed in all the specimens after 7 days. As carbonation time increased, the CO diffusion coefficient tended to decrease. This is because the diffusion of CO in the cement matrix follows the semi-infinite model of Fick's second law. SCAF can contribute to reduced energy consumption and CO emissions because of the low-temperature sintering and can absorb and fix CO when a certain amount is substituted.