## 3 Research on Alkali-Activated Grout Materials
### Study on UCS and Fluidity of Alkali-Activated Composite Grouting Material
#### 3.2.3 UCS Test Results and Analysis of Alkali-Activated Composite Grouting Material  
When the curing periods were 3, 7, and 28 days, UCS tests were conducted on alkali-activated composite grouting material samples to quantitatively evaluate the S/S effects of slag-fly ash alkali-activated composites under different influencing factors, as shown in Figure 8. The figure indicates that the strength of alkali-activated grout materials increases with the curing period. The primary growth period for strength is within the first 0-7 days. When cured for 3 and 7 days, the strength averages 56.2% and 86.1% of the 28-day strength, respectively. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c} \hline \hline
**Test Number** & **D-1** & **D-2** & **D-3** & **D-4** & **D-5** & **D-6** & **D-7** & **D-8** & **D-9** & **D-10** & **D-11** & **D-12** & **D-13** & **D-14** & **D-15** & **D-16** \\ \hline Fluidity/mm & 227.3 & 230.9 & 231.6 & 235.9 & 210.2 & 208.1 & 216.1 & 212.8 & 205.8 & 206.4 & 197.5 & 200.9 & 201.4 & 200.0 & 195.2 & 191.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Results of the alkali-activated composite grouting material fluidity test. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Level** & **Soil-to-Binder Ratio** & **Slaked Lime Content** & **Water-to-Solid Ratio** \\ \hline
1 & 197.1 & 211.2 & 206.2 \\
2 & 202.7 & 211.3 & 209.3 \\
3 & 211.8 & 210.1 & 212.5 \\
4 & 231.4 & 210.3 & 214.9 \\ Delta & 34.3 & 1.3 & 8.8 \\ Ranking & 1 & 3 & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Analysis of poor flowability in alkali-activated composite grouting material. Figure 7: Analysis of the average fluidity of alkali-activated grout materials. During the UCS testing of alkali-activated composite grouting material samples, failure occurred. When the pressure reached the load limit of the sample, numerous microcracks appeared in the compression zone. With increasing pressure, these microcracks expanded and extended, eventually leading to the disintegration and fragmentation of the material. The failure mode of the specimens is shown in Figure 9.  
Table 9 shows the extreme difference analysis of each factor on the UCS of alkali-activated grout materials at the maintenance ages of 3 days, 7 days, and 28 days. From the table, it can be seen that the influence of each factor on the UCS of alkali-activated grout materials at 3 days is arranged in ascending order as soil-to-binder ratio > slaked lime content > water-to-solid ratio, and the influence of alkali-activated grout materials at 7 days and 28 days on the UCS is arranged in ascending order as soil-to-binder ratio > water-to-solid ratio > slaked lime content. The alkali-activated composite grouting material reaches the highest UCS at the maintenance age of 28 days, while the soil-to-binder ratio corresponds to 5:5, the slaked lime content to 4.5%, and water-to-solid ratio to 0.26. A comprehensive comparison can conclude that the influence of each factor on the alkali-activated grout materials of the UCS is as follows: the soil-to-binder ratio is the main factor affecting the UCS of alkali-activated grout materials. At any maintenance age, with the decrease in the soil-to-binder ratio, its strength increases persistently. In the interval of the soil-to-binder ratio from 7:3 to 6:4, the 28-day UCS has the most obvious trend. When the maintenance age is 3 days, the second factor that affects the UCS is slaked lime, while, with the increase in the maintenance age to 7 days and 28 days, the second factor of UCS  
Figure 8: Group D specimens’ unconfined compressive strength at various ages. Figure 9: Forms of damage in alkali-activated composite grouting material samples. becomes the water-to-solid ratio. The UCS increased with the increase in the slaked lime content and increased with the decrease in the water-to-solid ratio at all ages. The reasons for the above situation are as follows.