## 3 Results and Discussion
### Xrd  
The XRD patterns were collected for CA-A, CG-A, NA-A, and NG-A samples at 7 and 28 days as shown in Figure 4, and the phases detected from XRD were listed in Table 4. The XRD data was analyzed using X'Pert HighScore Plus [22] based on reference patterns of the International Center for Diffraction Data (ICDD) PDF-2 database [23]. To identify calcium silicate hydrate (C-S-H), the experimental pattern of 23-year-old C-S-H, measured by [PERSON] and [PERSON] [24], was referenced after eliminating the reflections of calcium hydroxide because the reference pattern of C-S-H in the database (i.e., PDF 033-0306) showed only three major peaks (\(d\)-spacing = 3.04, 2.79, and 1.82 A) without amorphous characteristics. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Explanatory Factor**} & \multirow{2}{*}{**Entire Data Calculation**} & \multicolumn{2}{c}{**Separate Data Calculation**} \\ \cline{3-4}  & & **Group of CaO-Activation** & **Group of NaOH-Activation** \\ \hline Activator type (CaO vs. NaOH) & 0.00 & - & - \\ GGBFS source (type A vs. B) & 0.47 & 0.52 & 0.50 \\ CaSO\({}_{4}\) type (anhydrite vs. gypsum) & 0.33 & 0.49 & 0.02 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Calculated significance levels (\(p\)-values) of the explanatory factors from the factorial design using ANOVA. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**CaO-Activation**} & \multicolumn{4}{c}{**NaOH-Activation**} \\ \cline{2-9}
**Phase** & \multicolumn{2}{c}{**CA-A**} & \multicolumn{2}{c}{**CG-A**} & \multicolumn{2}{c}{**NA-A**} & \multicolumn{2}{c}{**NG-A**} \\ \cline{2-9}  & **7-Day** & **28-Day** & **7-Day** & **28-Day** & **7-Day** & **28-Day** & **7-Day** & **28-Day** \\ \hline \multicolumn{9}{c}{C-S-H formed in all the samples, but the relative comparison of the peak intensities} \\ \multicolumn{9}{c}{was not possible among samples because C-S-H is semi-amorphous.} \\ \hline Ettringite & \(\bullet\)\(\bullet  
All the samples produced a C-S-H phase; however, due to its amorphous nature, it was not possible to quantitatively compare the peak intensities of C-S-H in XRD with the samples in this study. Ettringite [Ca\({}_{6}\)Al\({}_{2}\)(SO\({}_{4}\))\({}_{3}\)(OH)\({}_{12}\)\(\cdot\)26H\({}_{2}\)O, AFt phase] also formed in all the samples. However, the CaO-activated samples produced significantly stronger ettringite peaks, unchanged after 7 days, than those of the NaOH-activated samples. In the CaO-activation, CA-A showed weak reflections of unreacted anhydrite at 7 days, which disappeared at 28 days, while CG-A exhibited noticeable peaks of unreacted gypsum until 28 days. At 28 days, it might appear as though CG-A contained a large quantity of unreacted gypsum because of the strong intensity of the first peak (see \(\blacksquare\) in Figure 4); note, however, that only the first peak was unusually strong when it was compared to that of the reference pattern of gypsum (i.e., PDF 01-070-0982), while the second peak (see \(\blacktriangledown\)) was much reduced from day 7 to day 28. Thus, CG-A at 28 days did not contain a large portion of unreacted gypsum (more discussion will be made later in Section 3.4). Nonetheless, the result showed that anhydrite was significantly more consumed than gypsum in the CaO-activation. In the NaOH-activation, NA-A and NG-A similarly showed complex phase compositions that consisted of U-phase (NaCa\({}_{4}\)Al\({}_{2}\)(SO\({}_{4}\))\({}_{1.5}\)(OH)\({}_{12}\)\(\cdot\)9H\({}_{2}\)O, AFm phase), Na\({}_{2}\)SO\({}_{4}\), akermanite (Ca\({}_{2}\)MgSi\({}_{2}\)O\({}_{7}\)), and ettringite, except that NG-A showed a small portion of remaining gypsum. It is worth noting that Na\({}_{2}\)SO\({}_{4}\) formed in both samples. In earlier studies [12; 25; 26], U-phase often formed when Na\({}_{2}\)SO\({}_{4}\) was present in cementitious systems, and it competed with ettringite under lowered pH environments. Thus, in the NaOH-activation, due to the substantial formation of U-phase, the ettringite formation seemed to be suppressed.