## 2 Materials and Methodology
### Effect of Temperature (23 \({}^{\circ}\)C, 40 \({}^{\circ}\)C, and 60 \({}^{\circ}\)C)  
To assess the effect of increasing temperature on CO2 capture, MRA, RCA, and CA-L were submitted to forced CO2 carbonation in a climatic chamber with the following conditions: 23 \({}^{\circ}\)C, 40 \({}^{\circ}\)C, and 60 \({}^{\circ}\)C, with a constant RH of 60% and a constant CO2 concentration of 25%.  
Figure 2 presents the maximum CO2 content captured by each RA in relation to the respective cement paste content at 23 \({}^{\circ}\)C, 40 \({}^{\circ}\)C, and 60 \({}^{\circ}\)C. The values ranged between 3.6 and 34.8%, with the highest value obtained in RCA IW1 at 23 \({}^{\circ}\)C.  
The increase in temperature from 23 \({}^{\circ}\)C to 60 \({}^{\circ}\)C did not cause significant differences in CO2 capture. Interestingly, the capture values obtained at 40 \({}^{\circ}\)C were lower in all RAs. Taking into account that 60 \({}^{\circ}\)C is the temperature that is closest to the temperature of blue gases in Portuguese cement factories, these results are promising. The temperature increase from 23 \({}^{\circ}\)C to 60 \({}^{\circ}\)C generally led to a decrease in the time required to achieve maximum CO2 capture. The enhancement in the carbonation reaction speed seems to be dependent on the portlandite and cement paste content present in the RA (Table 4). The results of the MRA show no significant difference in CO2 capture when increasing the temperature from 23 \({}^{\circ}\)C to 60 \({}^{\circ}\)C. Concerning the RCA and CA-L, different behaviours were found with the increment of temperature. Reductions were found in those with higher initial CO2 capture potential, meaning that they were low-carbonated before the forced carbonation (RCA-IW and CA-L). This phenomenon could be attributed to the fact that the carbonation reaction occurred faster at higher temperatures. Consequently, the rapid formation of CaCO3 during the early stages of carbonation creates a protective coating that shields unreacted cement components. The carbonated barrier obstructs the pores' structure, hindering the diffusion of CO2 into the cement matrix, ultimately leading to a lower CO2 capture [37; 38]. Additionally, a higher amount of CO2 can lead to more water being produced from carbonation reactions, making the pores more saturated and hindering CO2 penetration [39]. The low values of CO2 capture with increases in carbonation temperature can also be resultant of greater amounts of Ca2+ ions leaching from the silicates and reduced CO2 solubility, leading to higher pH values of the water, causing a lower dissolution rate of Ca2+ [40]. In terms of maximum CO2 uptake, the effect of increasing the temperature of carbonation varied among the different RA types, causing a non-linear tendency in the results (Table 5). This could be due to the respective compositions of the RAs and their initial carbonation states. Moreover, some studies, such as those by [PERSON] et al. [41] and [PERSON] et al. [42], argue that the transmission coefficient and reaction coefficient of CO2 increase with rising temperatures. As a result, more CO2 is able to penetrate the material and react with the hydration products. [PERSON] et al. [43] and [PERSON] and [PERSON] [44] claim that increasing the temperature from ambient levels to a threshold range of 60 to 80 \({}^{\circ}\)C enhances both the CO2 sequestration capacity and the carbonation speed of materials. However, beyond this threshold, a slight increase in temperature appears to have little effect or may even prevent mineral CO2 sequestration.