## 3 Results and Discussions  
### Changes in Hydraulic Time Composition with Mixing Percentage  
Figure 2 and Table 2 show the XRD results of the mixed potassium feldspar and limestone powder, with mass percentage ratios of 1:9, 2:8, 3:7, and 4:6 after burning for 3 h at 1000 \({}^{\circ}\)C. MDI Jade 9 software was used to calculate the mass percentage of the air-hardening component and hydraulic component of the samples via XRD. Jade software is able to conduct qualitative and semi-quantitative analyses of the samples, and the semi-quantitative analysis results are calculated primarily based on the peak value. The semi-quantitative analysis has a certain error in the analysis of the phase with relatively simple ingredients, but this error is within an acceptable range. Therefore, the results of this experiment are relatively reliable.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Components and Content**} & \multicolumn{6}{c}{**Mass Percentage (\%)**} \\ \cline{2-7}  & \multicolumn{3}{c}{**Air-Hardening Component**} & \multicolumn{3}{c}{**Hydraulic Component**} \\ \hline
**No.** & **CaO** & **Ca(OH)\({}_{2}\)** & **Total** & **C\({}_{2}\)S** & **C\({}_{2}\)AS** & **Total** \\ \hline K1 & 66.5 & 3.5 & 70.0 & 17.6 & 3.3 & 20.9 \\ \hline K2 & 40.9 & 10.2 & 51.1 & 28.4 & 10.1 & 38.5 \\ \hline K3 & 33.1 & 5.1 & 38.2 & 31.0 & 12.9 & 43.9 \\ \hline K4 & 29.6 & 5.1 & 34.7 & 27.4 & 19.3 & 46.7 \\ \hline NHL2 & 23.9 & 56.8 & 80.7 & 18.3 & 0.0 & 18.3 \\ \hline NHL5 & 45.0 & 20.2 & 65.2 & 33.8 & 0.0 & 33.8 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Mass percentage of the air-hardening component and hydraulic component for K1, K2, K3, K4, NHL2, and NHL5.  
The XRD characterization was performed after burning but before shaking. According to the XRD results, the resulting products after high-temperature calcination were primarily composed of CaO, 2 CaO*SiO2 (C2S), and 2 CaO*Al2O3*SiO2 (C2 AS). Among those products, CaO was the air-hardening cementing material, while C2S and C2 AS were the hydraulic-cementing materials [3]. After potassium feldspar and limestone were calcined at a mass ratio of 1:9, K1 generated 3.5% Ca(OH)2 and 66.5% CaO, 17.6% C2S, and 3.3% C2 AS.  
With an increase in the potassium feldspar proportion, the content of Al2O3 also gradually increased. Al2O3 and CaCO3 continued to generate C2 AS. The C2 AS content increased from 3.3% to 19.3%, while C2S slowly increased from K1 to K3, and K4 decreased slightly. With increasing potassium feldspar content, more C2 AS is generated, and the C2S content reaches its maximum when the potassium feldspar content is 30% at 1000 \({}^{\circ}\)C after burning for 3 h. Due to the production of C2S and C2 AS, the content of CaO in the sample gradually decreases. According to European Standards [20], the high content of CaO and Ca(OH)2 must be greater than or equal to 35%. The contents of CaO and Ca(OH)2 are higher than 35% in K1, K2, and K3, while K4 is less than 35%.  
Although K4 has more hydraulic components, its air-hardening phase is less than 35%. Therefore, K3 has more hydraulic phases than K1 and K2 and enhances the early strength of the test blocks even more. K3 is the best choice for comparison with NHL2 and NHL5.