## 2 Materials and Methods
### Methodology  
#### 2.2.1 Physical Activation Process Methods  
First, the natural volcanic rock was crushed and ground. Zirconia balls were selected as the grinding media, and the fineness and particle distribution of the volcanic rock powder were adjusted through the combination of different grades and grinding times. The finalized abrasive gradation was as follows: 2.5-5 mm accounted for 60%; 5-10 mm accounted for 30%; and 10-15 mm accounted for 10%. The time control was 15-60 min. The specific surface area of the ground volcanic rock powder was determined to be 480 m\({}^{2}\)/kg, 560 m\({}^{2}\)/kg, 640 m\({}^{2}\)/kg, and 735 m\({}^{2}\)/kg. The test method adhered to the Chinese standard GB/T 8074-2008 [41] and was conducted using the Hebei Hangxin FBT-9 type fully automatic specific surface area meter (Hebei Hangxin Instrument Co., Ltd., Shijiazhuang, China). Particle distribution was analyzed utilizing the German RODOS laser particle sizer (German Rodos GmbH, Kiel, Germany), in accordance with the Chinese standard GB/T 1907-2016 [42].  
According to the Chinese standard JG/T315-2011 [2], the activity index of volcanic rock powder with varying degrees of fineness were determined. The test conditions and methods outlined in the Chinese standard GB/T17671-2021 [43] were employed, utilizing prismatic cemented sand specimens with dimensions of 40 mm \(\times\) 40 mm \(\times\) 160 mm. The water-cement ratio was set at 0.5, with the dosage of volcanic rock powder constituting 30% of the mass of cement. The sand was ISO standard sand and the test mixing water was potable water. The amount of sand and water used in a single set of tests is 1350 g and 225 g, respectively. Using the above four specific surface areas of volcanic rock powders, prepare molded cemented sand specimens, and also mold a set of pure cement controls. The flexural and compressive strengths of the glued sand specimens were determined at 3, 7, 28, 60, and 90 days after standard curing and demolding, and the activity indices at different ages were calculated. Simultaneously, the samples were cut into small pieces of approximately 1 cm\({}^{3}\) each, and their surfaces were polished to achieve a smooth and flat finish. The morphological features were examined using a Hitachi S-4800 scanning electron microscope (SEM) (Hitachi High-Tech Corporation, Tokyo, Japan), and the chemical composition of the samples was analyzed by a Horiba 7021-H energy dispersive spectrometer (EDS) (Horiba Scientific, Kyoto, Japan).  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline
**Test Items** & **Loss** & **SiO\({}_{2}\)** & **Al\({}_{2}\)O\({}_{3}\)** & **Fe\({}_{2}\)O\({}_{3}\)** & **CaO** & **MgO** & **SO\({}_{3}\)** & **Na\({}_{2}\)O** & **K\({}_{2}\)O** & **R\({}_{2}\)O** \\ \hline Cement & 1.34 & 22.96 & 4.07 & 3.63 & 61.92 & 2.28 & 1.69 & 0.20 & 0.45 & 0.48 \\ \hline \end{tabular}
\end{table}
Table 2: Chemical composition of P-I silicate cement (%).  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Cement** &
\begin{tabular}{c} **Water** \\ **Consumption for** \\ **Standard** \\ **Consistency (\%)** \\ \end{tabular} & **Stability** & \multicolumn{2}{c}{**Condensation Time (min)**} & \multicolumn{2}{c}{**Compressive**} & \multicolumn{2}{c}{**Flexural Strength**} \\ \cline{4-9}  & **Stability** & \multicolumn{2}{c}{**Condensation Time (min)**} & \multicolumn{2}{c}{**Strength (MPa)**} & \multicolumn{2}{c}{**(MPa)**} \\ \cline{4-9}  & **Consistency (\%)** & \multicolumn{2}{c}{**Initial Setting**} & **Final Setting** & **3 d** & **28 d** & **3 d** & **28 d** \\ \hline “GB175-2023” & / & Qualified & \(\geq\)45 & \(\leq\)390 & \(\geq\)17 & \(\geq\)42.5 & \(\geq\)4.0 & \(\geq\)6.5 \\ \hline P.I. Silicate Cement & 27.2 & Qualified & 165 & 241 & 27.33 & 47.00 & 6.03 & 8.08 \\ \hline \end{tabular}
\end{table}
Table 3: P-I silicate cement physical performance indexes.