## 3 Results and Discussion
### Setting Time  
#### 3.2.1 Effect of One-Component Retarder on Setting Time of HBCSA Paste  
The setting time of HBCSA cement without retarder is between 17 and 21 min, and PCE mainly produces a dispersing effect in this cement but has little effect on prolonging the setting time of cement. From the setting time of the three single-component retarders (Table 2), it can be seen that the setting time of the cement paste is gradually prolonged when the content of \(\beta\)-CD is 0.1%. When the dosage reaches 0.3%, the retardation effect is more obvious. When the dosage reaches 0.7%, the setting time does not increase significantly, and only increases by 10% compared with the previous dosage. Some studies have shown [28] that with the increase of \(\beta\)-CD content, the setting time also continues to extend. In our research, when the \(\beta\)-CD content reaches 0.5%, the setting time does not increase significantly. So when the dosage of \(\beta\)-CD is 0.5%, the initial and final coagulation effect is the best. When the content of CA is as small as 0.1%, it has little effect on the setting time of HBCSA cement. When the content reaches 0.3%, the setting time increases with the increase in the content, and the maximum can be prolonged by 54 min and 79 min. However, when the content reaches 0.9%, the setting time does not show a regular increase but shows a downward trend. At a low dosage of B, the retardation effect is poor, and the retardation effect of 0.1%, 0.3%, 0.5%, and 0.7% is the same, which also shows that the change in dosage is too small and cannot prolong the setting time of HBCSA cement. When the dosage reaches 0.9%, the setting time of the initial setting and the final setting is only 14 min and 16 min longer than that of the blank group, so the retardation effect of B content on HBCSA cement is not obvious within 1%.  
Therefore, when the dosage is the same and higher than 0.1%, the retardation effect of citric acid and cyclodextrin is more significant. The coagulation time can reach about 1 h. This is reflected in the fact that both \(\beta\)-CD and CA molecules contain a hydrophilic group hydroxyl group. Due to adsorption, \(\beta\)-CD can associate with water molecules through hydrogen bonds, so a large number of solvated  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \(\beta\)**-CD** & & & **CA** & & & **B** & \\ \hline
**Content/\%** & **Initial** & **Final** & **Content/\%** & **Initial** & **Final** & **Content/\%** & **Initial** & **Final** \\ \hline
0.1 & 19 & 23 & 0.1 & 15 & 20 & 0.1 & 21 & 25 \\
0.3 & 43 & 55 & 0.3 & 38 & 45 & 0.3 & 21 & 25 \\
0.5 & 51 & 65 & 0.5 & 66 & 79 & 0.5 & 26 & 30 \\
0.7 & 58 & 68 & 0.7 & 71 & 100 & 0.7 & 26 & 30 \\
0.9 & 60 & 71 & 0.9 & 55 & 95 & 0.9 & 31 & 37 \\ \hline \hline \end{tabular} \end{water films are formed on the surface of cement particles, which hinders the direct contact between cement particles and water and effectively inhibits the reaction of (C4A3S) and CaSO4, particularly having the effect of inhibiting the dissolution rate of CaSO4, thereby inhibiting the hydration of cement [28]. The B4O72- and Ca2+ in borax will generate calcium borate [25; 27], but when the dosage is small, calcium borate is not enough to cover and seal the cement particles, and the cement will still be hydrated, so the retarding effect is not obvious enough.