# Preparation of Cementitious Material with Wet Fly Ash by Hydrothermal Reaction and Calcination
## 3 Results and Discussion
### Hydrothermal Synthesis System Analysis
#### 3.1.4 Quantitative Analysis of Reaction Products  
Following the law of conservation of mass, according to the chemical reaction equation in Equations (3)-(5), assuming that the total mass of reactants is 100 g, set the production amounts of the three hydration products C\({}_{2}\)SH, C\({}_{3}\)AH\({}_{6}\), and C\({}_{3}\)ASH\({}_{4}\) as \(x/\)g, \(y/\)g, and \(z/\)g, respectively, and solve for the range of values of \(x\), \(y\), and \(z\), respectively, according to the calculation equation in Equations (7)-(10), i.e., to obtain the range of the production contents of each of the three reaction products C\({}_{2}\)SH, C\({}_{3}\)AH\({}_{6}\), and C\({}_{3}\)ASH\({}_{4}\) in the fly ash-line system under the conditions of the autoclave process. This provides a basis for  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Sample No.** & **Experimental Parameters** & **Reaction Rate of Fly Ash/\%** \\ \hline
1 & 120 \({}^{\circ}\)C–4 h—22\% & 10.26 \\
2 & 140 \({}^{\circ}\)C–8 h—22\% & 15.39 \\
3 & 160 \({}^{\circ}\)C–6 h—22\% & 15.39 \\
4 & 160 \({}^{\circ}\)C–4 h—26\% & 13.52 \\
5 & 140 \({}^{\circ}\)C–6 h—26\% & 16.22 \\
6 & 120 \({}^{\circ}\)C–8 h—26\% & 16.32 \\
7 & 140 \({}^{\circ}\)C–4 h—30\% & 15.71 \\
8 & 120 \({}^{\circ}\)C–6 h—30\% & 17.14 \\
9 & 160 \({}^{\circ}\)C–8 h—30\% & 20.00 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Fly ash reaction degrees of different autoclaved samples.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample No.** & \begin{tabular}{c} **Experimental** \\ **Parameters** \\ \end{tabular} & \
\begin{tabular}{c} **Ca(OH)\({}_{2}\) Weight** \\ **Loss /wt\%** \\ \end{tabular} &
\begin{tabular}{c} **CaO Reaction Rate \%** \\ \end{tabular} \\ \hline
1 & 120 \({}^{\circ}\)C–4 h—22\% & 2.17 & 71.71 \\
2 & 120 \({}^{\circ}\)C–8 h—26\% & 3.30 & 63.85 \\
3 & 120 \({}^{\circ}\)C–6 h—30\% & 3.90 & 62.83 \\
4 & 140 \({}^{\circ}\)C–8 h—22\% & 1.66 & 78.63 \\
5 & 140 \({}^{\circ}\)C–6 h—26\% & 3.02 & 68.69 \\
6 & 140 \({}^{\circ}\)C–4 h—30\% & 3.99 & 62.00 \\
7 & 160 \({}^{\circ}\)C–6 h—22\% & 1.76 & 77.36 \\
8 & 160 \({}^{\circ}\)C–4 h—26\% & 3.10 & 66.06 \\
9 & 160 \({}^{\circ}\)C–8 h—30\% & 3.16 & 69.87 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Mass fraction of Ca(OH)\({}_{2}\) and CaO reaction degrees of different autoclaved samples.  
exploring the effect of changes in the autoclave process parameters on the formation and content of the products. The results of the calculations are shown in Table 5.  
\[(2x/190+3y/378+3z/402)\times 56=m(CaO) \tag{7}\]  
\[(y/378+z/402)\times 102=m\ (Al_{2}O_{3}) \tag{8}\]  
\[(x/190+z/402)\times 60=m\ (SiO_{2}) \tag{9}\]  
\[m(Al_{2}O_{3})+m(SiO_{2})=m(FA) \tag{10}\]  
where \(m(CaO)\) is the mass of the calcium oxide reaction, g; and \(m(FA)\) is the mass of the fly ash reaction, g.  
Increasing the steam autoclave reaction temperature and extending the reaction time is beneficial to improve the reaction degree of calcium oxide and fly ash and can also effectively reduce the free calcium oxide content. When the amount of fly ash is 22%, and the reaction temperature is 140 \({}^{\circ}\)C for eight hours, the reaction rate of calcium oxide is the highest at 78.63%, and the reaction rate of fly ash is 15.39% at this time. With the increase in reaction time and temperature, the amount of C\({}_{2}\)SH formation is gradually increased. The content of C\({}_{3}\)ASH\({}_{4}\) increased gradually with the increase in the reaction temperature. The reaction rate and product content of each raw material are similar when the reaction temperature is 140 \({}^{\circ}\)C and 160 \({}^{\circ}\)C, so the reaction temperature is chosen to be 140 \({}^{\circ}\)C for the reason of energy saving. Considering the above analysis, the best lime dosing ratio is 22%, and the steam autoclave reaction temperature is 140 \({}^{\circ}\)C for eight hours.