## 3 Results and Discussion
### Chemical Activation Process Test Results
#### 3.2.2 Orthogonal Test Extreme Variance and ANOVA Analysis  
Flexural and compressive strengths at 3 days, 7 days, and 28 days were determined for orthogonal test protocols with different dosages of CaO, CaCO\({}_{3}\), and CaCO\({}_{4}\cdot\)2H\({}_{2}\)O. The range analysis is shown in Figures 16-18, and the ANOVA results are shown in Figure 19, which clarified the important role of the three reagents and their different dosages on the effect of activity enhancement, as well as the superimposed enhancement effect among them. Figure 15: Compressive strength and activity index curves of collodion sand specimens of different ages with different reagents. Figure 16: Flexural (**a**) and compressive (**b**) strength k-value curves at different dosages and ages. Figure 17: Curves of extreme values of flexural strength versus time for different dosages of volcanic rock powder. Figure 16a shows that the flexural strengths of the same reagents exhibited similar trends with age. The strengths of CaO and CaCO\({}_{3}\) 2H\({}_{2}\)O first increased and then decreased, while the opposite was true for CaCO\({}_{3}\). The highest flexural strength was found in the 2% dosed CaCO\({}_{4}\) 2H\({}_{2}\)O, which played a dominant role. The strengths of 2% dosed CaCO\({}_{3}\) were slightly lower than those of the other two ages at 7 days, and the 6% dosed CaO also demonstrated an excellent performance. Considering the flexural strength at all ages, the optimum combination of dosing was 6% CaO + 2% CaCO\({}_{3}\) + 2% CaCO\({}_{4}\) 2H\({}_{2}\)O. Figure 17 shows that CaSO\({}_{4}\) 2H\({}_{2}\)O had the greatest effect on all ages, followed by CaCO\({}_{3}\), and CaO had the smallest effect. Therefore, the order of the effects of the three reagents on flexural strength was CaSO\({}_{4}\) 2H\({}_{2}\)O \(>\) CaCO\({}_{3}\) \(>\) CaO. Figure 16b shows that the compressive strength of 2% doped CaSO\({}_{4}\) 2H\({}_{2}\)O followed the same variation rule as the flexural strength. Additionally, 2% doped CaCO\({}_{3}\) performed well at 7 and 28 days. Furthermore, 5% doped CaO exhibited greater strength in the early stage,  
Figure 19: F value curve of variance of flexural (**a**) and compressive (**b**) strength at different ages. Figure 18: Curves of extreme values of compressive strength versus time for different dosages of volcanic rock powder. while 7% doped CaO dominated at 28 days. Considering the compressive strength at each age, the best combination of dosing was as follows: 5% CaO + 2% CaCO\({}_{3}\) + 2% CaCO\({}_{4}\cdot\)2H\({}_{2}\)O. Figure 18 shows that CaCO\({}_{4}\cdot\)2H\({}_{2}\)O had the greatest influence at 3 days and decreased first and then rose with age; the change rule of CaO and CaCO\({}_{3}\) was the same as theirs, but the influence of CaCO\({}_{3}\) was the greatest at 28 days. Therefore, the order of influence of the three reagents on compressive strength was as follows: CaCO\({}_{4}\cdot\)2H\({}_{2}\)O \(>\) CaCO\({}_{3}\)\(>\) CaO. We calculated the sum of squared deviations, degrees of freedom, and the F value of flexural and compressive strength, and checked the F test critical value table: F0.10(2,2) = 9; F0.05(2,2) = 19; F0.01(2,2) = 99. The influencing factors were divided into insignificant (F \(<\) F0.10(2,2)), relatively significant (F0.10(2,2) \(<\) F \(<\) F0.05(2,2)), significant (F0.05(2,2) \(<\) F \(<\) F0.01(2,2)), and particularly significant (F \(\geq\) F0.01(2,2)). We evaluated the significant impact of each reagent and dosage (Figure 19). The significance analysis of flexural strength (Figure 19) revealed that the F values for CaO (3 d and 7 d) and CaCO\({}_{4}\cdot\)2H\({}_{2}\)O (7 d and 28 d) fell within the ranges of F0.05(2,2) and F0.01(2,2), corresponding to the 19-99% confidence interval, indicating a significant impact. Notably, the F value for 28 d CaO exceeded the 99% confidence level, and the F value for CaCO\({}_{3}\) was within a similar range, increasing with age. This suggests that this dosage had a particularly significant effect on flexural strength.