## Experimental Results and Discussion
### Co\({}_{2}\) Uptake  
The CO\({}_{2}\) uptake was calculated from the TG/DTG measurements using Equation (2) [21].  
\[\text{CO}_{2}\text{ uptake [wt.\%]}=\Delta\text{W/W}_{\text{d}} \tag{2}\]  
where W\({}_{\text{d}}\) is the weight of the specimen dried at 105 \({}^{\circ}\)C and \(\Delta\)W is the weight difference before and after carbonation curing (550-850 \({}^{\circ}\)C).  
Figure 11 shows the CO\({}_{2}\) uptake for the specimens according to CO\({}_{2}\) concentration. The variation in CO\({}_{2}\) uptake was found to be within 7%. As shown in the graph, the CO\({}_{2}\) uptake increased as the CO\({}_{2}\) concentration increased for STP0. The CO\({}_{2}\) uptake of STP0 was not significant at 10% CO\({}_{2}\) concentration, but it almost doubled at 15% CO\({}_{2}\) concentration. For STP30 and STP60, the CO\({}_{2}\) uptake increased significantly by the carbonation of the AOD slag under CO\({}_{2}\) curing. The increase was most significant when the CO\({}_{2}\) concentration was 5%. The CO\({}_{2}\) uptake of STP60 increased compared to that of STP30, but it did not increase in proportion to the mixed amount of AOD slag. This can be attributed to the influences of solubility, diffusivity and reaction rate of CO\({}_{2}\).  
The non-CO\({}_{2}\) cured specimens exhibited similar CO\({}_{2}\) uptake values (approximately 1.5%) regardless of the curing temperature, as shown in Figure 12. At CO\({}_{2}\) concentration of 5%, for STP0, the CO\({}_{2}\) uptake increased by approximately 1% due to the curing temperature change. This could also be confirmed via the compressive strength and MIP measurements. For STP30 and STP60, the CO\({}_{2}\) uptake significantly increased. However, the CO\({}_{2}\) uptake increased by approximately 1% only as the curing temperature increased for STP30 and STP60.  
Figure 10: Cumulative intrusion for specimens according to curing temperature.  
uptake compared to STP30. If the CO2 uptake increases further, STP30 and STP60 are expected to exhibit smaller diffusion coefficients than STP0.  
Figure 13b shows the comparison between the CO2 uptake and chloride diffusivity according to curing temperature at a CO2 curing centration of 5%. The figure also shows that the chloride diffusivity decreases and the CO2 uptake increases as the temperature increases. In the cases of STP0 and STP30, the chloride diffusion coefficient decreased slightly when the curing temperature increased from 23 to 40 \({}^{\circ}\)C. For STP60, the reduction in the chloride diffusion coefficient was significantly larger than that of STP0 and STP30. To secure the durability of high-volume AOD slag concrete, the curing temperature should be increased.  
Figure 14a shows the comparison between the CO2 uptake and drying shrinkage. The drying shrinkage reduced as the CO2 uptake increased. For STP0, the drying shrinkage significantly reduced, even though the CO2 uptake was less than 5%, which was much lower than that of STP30 or STP60. For STP30 and STP60, the drying shrinkage reduced in proportion to the increase in the CO2 uptake. The overall reduction in drying shrinkage was similar for all variables.  
The CO2 uptake increased, and the drying shrinkage was reduced as the temperature increased regardless of the AOD slag substitution rate, as shown in Figure 14b. The drying shrinkage of STP0 was significantly reduced as the curing temperature increased as shown in Figure 6, even though the CO2 uptake was extremely low. For STP30 and STP60 with AOD slag, however, small changes were  
Figure 14: Comparison between CO2 uptake and drying shrinkage: (**a**) CO2 concentration and (**b**) curing temperature.  
Figure 13: Comparison between CO2 uptake and chloride diffusivity: (**a**) CO2 concentration and (**b**) curing temperature.  
observed in the drying shrinkage, and the drying shrinkage decreased as the CO2 uptake increased regardless of the replacement level of the AOD slag. It was found that the drying shrinkage of OPC is more affected by CO2 curing temperature than AOD slag.