## 3 Results and Discussion
### Discussion of Orthogonal Experimental Results
#### 3.1.1 Effect of Factors on the Fluidity Ratio of Composite Micronized Powder
As a result, an excessive amount of BFS powder will instead deteriorate the slurry's fluidity, which also explains the phenomenon that the fluidity ratio increases first and then decreases with the increase in the amount of BFS compound micronized powder [18]. The viscosity of the slurry is the main factor affecting the fluidity, and the resistance is high when the viscosity is too high, leading to reduced flow. The addition of MTS can properly reduce the viscosity of the slurry, thus improving the mortar fluidity [19]. The role of GA is to improve the ease of grinding solid waste materials, ensuring a more uniform mixture and concentrated fineness. The slurry prepared with the composite micro powder exhibits reduced sliding resistance, thus increasing the fluidity of the slurry [20]. The structure of DG is a dense structural network formed by short columnar crystals in contact with each other, and the increase in its doping quantity will reduce the flow of the system, but when its doping quantity is greater than a certain reasonable range, the flow of the system increases due to its higher water content [21]. 1.2 Influence of Factors on the Performance of Composite Micronized Powder against Chloride Ion Penetration  
As can be seen from Table 5, the main law of the influence of each factor on the substrate resistance to chloride ion penetration is A \(>\) D \(>\) C \(>\) B. Figure 2 shows the effect curve of each factor on the substrate electric flux. From Figure 2, it can be seen that with the increase in BFS, DG and GA doping, the electric flux of the matrix decreases and the resistance to chloride ion penetration increases; conversely, with an increase in MTS doping, the electric flux of the matrix first increases and then decreases, and the resistance to chloride ion penetration of the matrix first decreases and then increases. The matrix prepared with the composite micronized powder has the best resistance to chloride ion penetration when the ratio is A4B4C4D4, i.e., 35% BFS, 30% MTS, 0.3% GA, 10% DG and 25% WQMS. Table 6 shows the grading of the chloride ion permeation resistance of concrete by the electric flux method. Combined with the results of the orthogonal experiments in Table 4, it can be seen that the chloride ion permeation resistance of the composite micropowder matrix reaches Q-II grade, with some reaching Q-III grade. Figure 1: Graph showing the effect of each factor on the fluidity ratio of composite micronized powder. The ability of BFS and DG to enhance the chloride ion penetration resistance of the matrix can be attributed to their two effects in the cementitious system, namely, the volcanic ash effect and the filling effect [22; 23]. The volcanic ash effect of BFS and DG is manifested by the secondary reaction of glass phase SiO\({}_{2}\) and Al\({}_{2}\)O\({}_{3}\) in BFS and DG with cement hydration product Ca(OH)\({}_{2}\) in the alkaline environment of the cementitious system, and the formation of cementitious materials such as hydrated calcium silicate and hydrated calcium aluminate improves the compactness and volume stability of the matrix, and it is more challenging for chloride ions to penetrate. The filling effect of BFS and DG is shown by the fact that during the hydration process of cement, BFS and DG micropowder particles with smaller particle size than cement, which are not involved in the reaction, are evenly dispersed in the pores and cementitious body, playing the role of filling capillary pores and pore cracks, improving the pore structure and the compactness of the matrix, thus reducing the chloride ion permeability. The mechanism of action of the two effects can be summarized as the incorporation of BFS and DG leads to a denser microstructure with a matrix having fewer interconnected pores [24].