###### Abstract  
To disclose influences of ultrasonic vibration agitation on the carbonation resistance of cement-based materials after absorption of CO\({}_{2}\), the variation laws in internal carbonization zone were explored by the testing carbonization depth and carbonization range (pH variation range) of cement mortar after CO\({}_{2}\) absorption at different ages. Results demonstrated that when CO\({}_{2}\) absorption volumes of the cement mortar before carbonization were 0.44%, 0.88%, 1.32%, 1.76%, and 2.20% (28 d), the carbonization depth under ultrasonic vibration decreased by 5.5%, 12.3%, 21.7%, 20.7%, and 26.7% compared to those under mechanical stirring, respectively. When the ultimate CO\({}_{2}\) absorption volume increased to 2.2% of cement mass, the extended degree of cement mortar was 103.23 mm, which decreased by 5.4% compared to that before CO\({}_{2}\) absorption. pH variation values of the carbonization range under ultrasonic vibration presented a rising trend with the increase of CO\({}_{2}\) absorption volume of cement mortar before carbonation. This indicated that, with the increase of CO\({}_{2}\) absorption volume of cement mortar before carbonation increases under ultrasonic vibration, the carbonization process of the hardened body of cement mortar might be dedeelerated to some extent. Additionally, changes in internal composition and physical images of cement-based materials after absorption of CO\({}_{2}\) were analyzed through microtest means like SEM and XRD. A carbonation resistance model was constructed, thus enabling disclosure of the variation mechanism of carbonation resistance of cement-based materials after absorption of CO\({}_{2}\) under mechanical stirring and ultrasonic vibration. Results demonstrated that the higher CO\({}_{2}\) absorption volume of fresh slurry generated more \"nano-level\" CaCO\({}_{3}\) crystal nucleus. Accordingly, it could improve the porous structure of the cement mortar, decrease the quantity of capillary tubes significantly, improve the compaction degree of cement-based materials effectively, and lower the diffusion rate of CO\({}_{2}\) in the cement paste base, thus improving the carbonation resistance. Research conclusions have important significance to decrease CO\({}_{2}\) emissions and improve carbonation resistance of concrete. f 202  
emission reduction has become one of the hot topics in energy policy and environmental administration [7; 8; 9]. At present, sealing and solidification of CO2 are the most common methods to decrease carbon emissions. Mineral carbonization and marine sequestration are the most common methods. However, the natural carbonization of minerals takes a long time since it is very slow. To accelerate the reaction, it is necessary to enhance minerals in advance, which may incur excessive energy consumption. Therefore, sealing potentials of mineral carbonization are not so optimistic. Besides, marine sequestration may increase CO2 concentration on seawater surface, thus changing chemical characteristics of marine ecosystem and causing various problems like ocean acidification. Hence, concrete was applied to absorb, recycle, and solidify CO2. This has important significance to realize sustainable development of the concrete industry, relieve greenhouse gas emission, and solve global warming. Therefore, it is urgent to explore a new method for CO2 sealing and solidification. As everyone knows, cement in concrete may produce a lot of Ca(OH)2 during hydration, which accounts to a high proportion (about 20-30%) in cement. Most of Ca(OH)2 exists in cement stone pores as crystals. Ca(OH)2 can react with CO2 in solution to produce CaCO3. This is also another important reason that concrete has such considerable CO2 absorption volume. Compared with mineral carbonization and marine sequestration, CO2 absorption based on concrete has stronger operability and more promising application prospects. China's strategies for CO2 emission reduction are significantly different from those of other countries.