## 3 Experimental Results
### Tg  
The results of the 3-day thermogravimetric (TG) and differentiated thermogravimetry (DTG) tests are shown in Figure 8a,b, respectively. Figure 8a shows that the loss of ignition in the sample decreases as the amount of quartz powder substitution increases. This is because quartz powder is basically non-chemically reactive, resulting in a reduction in the quality of chemically bound water. Figure 8b shows that the mass loss peak at around 100 degrees corresponds to the decomposition of C-S-H and AFt. The mass loss peak at around 180 degrees corresponds to the decomposition of HC and Mc. The mass loss peak between 400 and 500 degrees corresponds to the decomposition of CH. The mass loss peak between 550 and 900 degrees corresponds to the decomposition of various forms of calcium carbonate, which mainly comes from the cementitious materials used [39]. Based on the results of our TG testing, we can calculate the contents of chemically bound water and calcium hydroxide, as shown in Equations (1) and (2), respectively [23]:  
\[H_{a}=\frac{M_{40}-M_{550}}{M_{550}}\times 100\% \tag{1}\]  
\[F_{a}=\frac{M_{400}-M_{500}}{M_{500}}\times 100\% \tag{2}\]  
Figure 8: Curves of Qu0, Qu7.5, and Qu15 over 3 days: (**a**) TGA; (**b**) DTG.  
\(M_{40},M_{400}\), and \(M_{500}\) correspond to the quality of the sample at 40 degrees, 400 degrees, and 500 degrees, respectively. The calculation results for the chemically bound water and calcium hydroxide after 3 days are shown in Table 3, where we can see that both of their masses decreased as the substitution amount increased.  
Figure 9a,b show the calculation results for the 28-day TG and DTG tests, respectively. Comparing Figures 8a and 9a, we can see that the overall trend is similar. As the amount of quartz powder substitution increases, the mass loss decreases. From Day 1 to Day 28, the amount of mass loss increases because of an increase in hydration products, which generates more chemically bound water. Figure 9b shows that the hydration product contents, that is, CH and CSH, decrease as the amount of quartz powder substitution increases.  
Calculations for chemically bound water and calcium hydroxide at 28 days are shown in Table 4. As the amount of quartz powder substitution increases, the chemically bound water and CH contents decrease, which indicates that the dilution effect of quartz powder plays a dominant role in those 28 days.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Qu0** & **Qu7.5** & **Qu15** \\ \hline Combined water (wt\%) & 13.15 & 12.23 & 11.46 \\ Portlandite (wt\%) & 14.80 & 14.12 & 13.51 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Combined water and portlandite in Qu0, Qu7.5, and Qu15 after 3 days.  
Figure 9: Curves of Qu0, Qu7.5, and Qu15 after 28 days: (a) TGA; (b) DTG.  
The development of macro-properties can reflect the evolution of concrete's microstructure. As combined water increases, hydration products form, and strength also increases. Hence, combined water and strength have a close relation. Figure 10 shows the relationship between chemically bound water and strength. We can see that for different specimens (Qu0, Qu7.5, and Qu15) at different test times (3 and 28 days), there is an exponential function relationship between chemically bound water and strength [31; 32]. The chemically bound water unit is g/g binder, and the strength unit is MPa.