## 3 Results and Discussion
### Carbonation Product Characterization  
Figure 8a-f illustrate the evolution patterns of carbonation uptake rates and 28-day phase composition characteristics of carbonation-cured specimens under varying temperature-humidity conditions. As the relative humidity increased from 60% to 80%, the carbonation uptake rates exhibited a gradual decline, indicating limited humidity-dependent modulation of carbonation reactions. This behavior arises from humidity gradients induced by internal-external humidity differentials, which drive the formation of continuous water films at the specimen surfaces. These films physically inhibit CO\({}_{2}\) transport efficiency into internal pore networks through barrier effects. Concurrently, high-humidity environments intensify pore water blocking effects, confining carbonation reactions to surface regions and reducing kinetic rates. Figure 7: Effects of temperature on pore solution pH at varying depths under different humidity conditions: (**a**) 60% RH, (**b**) 70% RH, (**c**) 80% RH. XRD phase analysis (tested on specimens at 3 mm depth from the exposed surface) shows that, compared with the standard curing group, the characteristic calcite (CaCO\({}_{3}\)) diffraction peak intensity (20 = 29.4\({}^{\circ}\)) in carbonation-cured specimens is significantly enhanced, confirming that calcite is the dominant carbonation product. This aligns with the findings of [PERSON]. [PERSON] et al., whose study on alkali-activated slag materials identified the main factors controlling the decalcification degree of C-A-S-H gels and demonstrated that calcite is the sole crystalline calcium carbonate formed in carbonated alkali-activated slag pastes [49]. The higher the crystallinity of the crystal, the higher the intensity of the corresponding diffraction peak and the sharper the shape of the diffraction peak. With the increase in humidity, the diffraction peaks of calcite show a sharper morphology and intensity increase, indicating that its crystallinity is improved. This suggests that the continuous water film on the surface and the retarding effect of pore water compromise the crystallographic integrity of carbonation products. Lower crystallinity weakens the me  
Figure 8: Effects of humidity on carbon uptake rate and 28-day phase composition under different temperatures: (**a**,**b**) 10 \({}^{\circ}\)C, (**c**,**d**) 20 \({}^{\circ}\)C, (**e**,**f**) 30 \({}^{\circ}\)C.  
chanical interlocking effect between calcite particles, leading to a reduced filling efficiency of harmful surface pores and diminished mechanical performance enhancement. Figure 9a-f characterize the effects of temperature variations on carbon uptake rate and product composition in alkali-activated slag-solidified shield much under different humidity conditions. The experimental data demonstrate a significant increasing trend in the carbon uptake rate with temperature elevation (10-30 \({}^{\circ}\)C), indicating enhanced carbonation reaction kinetics through thermal activation. This enhancement mechanism originates from the temperature-dependent acceleration of CO2 diffusion coefficients, improved Ca2+ solubility, and evaporation-induced alkaline ion migration, which synergistically promote carbonation product formation. Figure 9: Effects of temperature on carbon uptake rate and 28-day phase composition under different humidity conditions: (**a,b**) 10 \({}^{\circ}\)C, (**c,d**) 20 \({}^{\circ}\)C, (**e,f**) 30 \({}^{\circ}\)C.  
An XRD phase analysis demonstrated that the carbonation products across different temperature groups were predominantly composed of calcite-type calcium carbonate (CaCO\({}_{3}\)). The characteristic diffraction peak intensity at 20 = 29.4\({}^{\circ}\) increased with elevated temperatures, accompanied by sharpened peak morphology.