## 3 Results and Discussion
### Scanning Electron Microscopy Analysis  
The morphology of the multicomponent solid waste cementitious material was characterized through a scanning electron microscopy (SEM) test to illustrate the changes in GBFS hydration products under alkali-sulfur co-excitation (Figures 8 and 9). Generally, the hydration products exhibited varying micro-morphologies. Among them, the C-S-H gel exhibited a reticular morphology, AFt exhibited a needle-like rod morphology, and Ca(OH)\({}_{2}\) exhibited a hexagonal plate morphology. As shown in Figure 8a, the EGC0 group was the control group. On day 3, a large amount of incomplete GBFS, with smooth and glassy surfaces and a reduced quantity of hydration products, was found. As shown in Figure 8b-d, with the addition of CS or EMR, the hydration products generated were relatively simple, but with the addition of CS and EMR, small amounts of AFt, C-S-H gel, and other hydration products were slowly generated, and the amount of GBFS was reduced. This indicates that the early activity of GBFS was effectively improved under alkali-sulfur co-activation, leading to higher strength. This observation was consistent with the 3 d compressive strength data.  
employed three types of industrial solid waste that met the above conditions to promote the hydration reaction and consequently generate more hydration products, particularly AFt. The optimal reaction ratio and reaction mechanism of the three waste materials were studied. Figure 10 illustrates the reaction mechanisms of the multicomponent solid waste cementitious materials.  
As shown in Figure 10a, mechanical grinding and GBFS activation were conducted to refine GBFS and increase the hydration reaction area to enhance the generation of hydration products. Moreover, under the influence of high-energy impact, GBFS can promote the depolymerization of the vitreous body, leading to the breakage of surface bonds and lattice defects. A large number of aluminate and silicate groups can dissolve in an aqueous solution, promoting the formation of C-S-H gel and AFt. As shown in Figure 10b, in the presence of insufficient EMR and excessive CS, the early stage generation of AFt was limited, which affected the early strength of the sample. However, as the hydration reaction  
Figure 10: Reaction mechanism of multicomponent solid waste cementitious material.  
progressed, a small amount of AFt was generated in the later hydration stage mainly because the cement contained a small amount of gypsum phase to provide SO42\({}^{-}\) to participate in the AFt reaction. Therefore, the main hydration product providing strength in this system was the C-S-H gel, of which the chemical reaction formula is shown in Equation (1) [32].  
\[SiO_{2}+xCa(OH)_{2}+(n-1)H_{2}O\to xCaO\cdot SiO_{2}\cdot nH_{2}O \tag{1}\]  
In contrast, as shown in Figure 10d, in the presence of insufficient CS and excessive EMR, the AFt formation rate was higher in the early stage, which effectively improved the early strength of the cementing material, and a large amount of AFt was generated in the late hydration stage; however, the AFt morphology was long and fine, the C-S-H gel amount was small, and the structure density was poor. The AFt generation chemical reaction is shown in Equation (2) [37].  
\[Al_{2}O_{3}+3(CaSO_{4}\cdot 2H_{2}O)+3 Ca(OH)_{2}+23H_{2}O\to 3 CaO\cdot Al_{2}O_{3} \cdot 3 CaSO_{4}\cdot 32H_{2}O \tag{2}\]  
As illustrated in Figure 10c, the incorporation of appropriate CS and EMR contents played a positive role in both the early and late hydration of the gelling material. This was primarily attributed to the generation of a significant amount of AFt and C-S-H gel hydration products, with both products interlacing and forming relatively dense structures.