## 3 Experimental Analysis of Steam Curing and Orthogonal Matching Ratio
### Orthogonal Experiment Mix Proportion Design
#### 3.3.3 Analysis of Variance Significance  
The results of the variance significance analysis are shown in Table 18 below:  
According to the analysis of variance results in Table 18, both coal gangue content and additional water content exhibit a statistically significant effect on the compressive strength  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Indicator** & \begin{tabular}{c} **Different Factors and** \\ **Levels** \\ \end{tabular} & \begin{tabular}{c} **Sum of** \\ **Squares** \\ \end{tabular} & \begin{tabular}{c} **Degree of** \\ **Freedom** \\ \end{tabular} & \
\begin{tabular}{c} **Mean** \\ **Square** \\ \end{tabular} & **F-Value** &
\begin{tabular}{c} **F\({}_{\alpha}\)(f\({}_{\alpha}\)f\({}_{\mathrm{b}}\))** \\ \end{tabular} \\ \hline \multirow{7}{*}{3 d} & Coal gangue content A & 25.897 & 2 & 12.949 & 413.11 (**) & \\  & Coarse aggregate & & & & \\  & particle size B & 0.056 & 2 & 0.028 & 0.89 () & \\  & Additional water & & & & & F\({}_{0.01}\)(2,2) = 99.0 \\ strength/MPa & consumption C & 4.446 & 2 & 2.223 & 70.916 (*) & F\({}_{0.05}\)(2,2) = 19.0 \\  & error & 0.63 & 2 & 0.315 & & \\  & Total & 30.461 & 8 & & & \\ \hline \multirow{7}{*}{7 d} & Coal gangue content A & 24.886 & 2 & 12.443 & 145.00 (**) & \\  & Coarse aggregate & & & & & \\  & particle size B & 0.082 & 2 & 0.041 & 0.478 () & \\  & Additional water & & & & F\({}_{0.01}\)(2,2) = 99.0 \\ strength/MPa & consumption C & 5.887 & 2 & 2.944 & 34.30 (*) & F\({}_{0.05}\)(2,2) = 19.0 \\  & error & 0.172 & 2 & 0.086 & & \\  & Total & 31.026 & 8 & & & \\ \hline \multirow{7}{*}{14 d} & Coal gangue content A & 28.747 & 2 & 14.374 & 479.12 (**) & \\  & Coarse aggregate & & & & & \\  & particle size B & 0.16 & 2 & 0.08 & 2.67 () & \\  & Additional water & & & & F\({}_{0.01}\)(2,2) = 99.0 \\ strength/MPa & consumption C & & & & & \\  & error & 0.06 & 2 & 0.03 & & \\  & Total & 36.368 & 8 & & & \\ \hline \multirow{7}{*}{28 d} & Coal gangue content A & 54.013 & 2 & 27.006 & 452.87 (**) & \\  & Coarse aggregate & & & & & \\  & particle size B & 0.125 & 2 & 0.063 & 1.045 () & \\ \cline{1-1}  & Additional water & & & & & F\({}_{0.01}\)(2,2) = 99.0 \\ \cline{1-1}  & consumption C & 7.685 & 2 & 3.843 & 64.44 (*) & F\({}_{0.05}\)(2,2) = 19.0 \\ \cline{1-1}  & error & 0.119 & 2 & 0.06 & & \\ \cline{1-1}  & Total & 61.942 & 8 & & & \\ \hline \hline \end{tabular}  
* The critical values for F\({}_{0.01}\)(2,2) and F\({}_{0.05}\)(2,2) are 99 and 19, respectively. If the calculated F value is greater than F\({}_{0.01}\)  
of coal gangue concrete, whereas the effect of maximum aggregate particle size is negligible. The ranking of influencing factors across different curing ages (3, 7, 14, and 28 days) is as follows: coal gangue content \(>\) additional water content \(>\) maximum aggregate particle size, which aligns with the findings from the range analysis.  
Based on the results of the range and variance analyses, and under the requirement of achieving a design compressive strength of 30 MPa, the optimal mix design for coal gangue concrete is determined to be a coal gangue content of 20%, a maximum aggregate particle size of 20 mm, and an additional water content of 70% of its saturated water absorption capacity.