## 2 Physical Properties of Sandstone after Different Times of Corrosion by Strong Alkali Solution
### Density and Mass Variation
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & \multicolumn{3}{c}{**Non-Coroded**} & & & & **Coroded** & & & \\
**Sample Name** & **Mass** & **Length** & **Diameter** & **Density** & **Corrosion Time** & **Mass** & **Length** & **Diameter** & **Density** \\  & **(g)** & **(mm)** & **(mm)** & **(g cm\({}^{-3}\))** & **(d)** & **(g)** & **(mm)** & **(mm)** & **(g cm\({}^{-3}\))** \\ \hline DJ11-26 & 123.03 & 24.97 & 50.05 & 2.506 & & & & & \\ DJ11-27 & 126.32 & 25.08 & 50.05 & 2.561 & & & & & \\ DJ11-28 & 127.36 & 25.11 & 50.01 & 2.584 & 0 & & (non-corroded) & & \\ DJ11-29 & 127.39 & 25.12 & 50.04 & 2.581 & & & & & \\ DJ11-30 & 126.74 & 25.09 & 50.11 & 2.572 & & & & & \\ \hline DJ11-01 & 127.59 & 25.14 & 50.06 & 2.581 & & 127.87 & 25.12 & 50.12 & 2.582 \\ DJ11-02 & 125.05 & 25.00 & 49.97 & 2.552 & & 125.50 & 24.95 & 50.10 & 2.554 \\ DJ11-03 & 123.36 & 25.10 & 50.04 & 2.500 & 1 & 124.02 & 25.11 & 50.15 & 2.503 \\ DJ11-04 & 127.17 & 25.04 & 50.06 & 2.582 & & 127.47 & 25.03 & 50.12 & 2.583 \\ DJ11-05 & 127.28 & 25.01 & 50.08 & 2.585 & & 127.61 & 25.03 & 50.09 & 2.589 \\ \hline DJ11-06 & 126.89 & 25.03 & 50.01 & 2.582 & & & 127.62 & 25.09 & 49.90 & 2.603 \\ DJ11-07 & 123.18 & 24.84 & 50.02 & 2.525 & & & 124.09 & 24.94 & 50.14 & 2.530 \\ DJ11-08 & 127.20 & 25.05 & 50.07 & 2.581 & & 127.68 & 25.03 & 50.09 & 2.590 \\ DJ11-09 & 125.12 & 25.10 & 50.03 & 2.537 & & & 125.89 & 25.08 & 50.17 & 2.541 \\ DJ11-10 & 127.73 & 24.99 & 50.06 & 2.598 & & & 128.23 & 24.98 & 50.15 & 2.601 \\ \hline DJ11-11 & 128.70 & 25.02 & 50.10 & 2.612 & & & 129.34 & 25.00 & 50.16 & 2.620 \\ DJ11-12 & 127.81 & 24.97 & 50.00 & 2.608 & & & 128.45 & 25.02 & 50.20 & 2.627 \\ DJ11-13 & 124.62 & 25.01 & 50.01 & 2.539 & 7 & & 125.68 & 25.12 & 50.15 & 2.544 \\ DJ11-14 & 127.09 & 25.09 & 50.01 & 2.581 & & & 127.77 & 25.12 & 50.07 & 2.585 \\ DJ11-15 & 126.81 & 25.10 & 50.09 & 2.565 & & & 127.46 & 25.06 & 50.14 & 2.577 \\ \hline DJ11-16 & 128.19 & 25.08 & 50.02 & 2.603 & & & 129.05 & 25.09 & 50.11 & 2.610 \\ DJ11-17 & 126.75 & 25.01 & 50.04 & 2.579 & & & 127.48 & 24.99 & 50.09 & 2.591 \\ DJ11-18 & 129.14 & 25.08 & 50.04 & 2.619 & & & 129.80 & 25.17 & 50.12 & 2.625 \\ DJ11-19 & 125.97 & 25.11 & 50.07 & 2.549 & & & 127.07 & 25.11 & 50.16 & 2.562 \\ DJ11-20 & 128.14 & 25.10 & 50.03 & 2.599 & & & 128.93 & 25.15 & 50.13 & 2.600 \\ DJ11-21 & 128.48 & 25.12 & 50.05 & 2.602 & & & 129.11 & 25.13 & 50.22 & 2.666 \\ DJ11-22 & 126.26 & 25.07 & 49.99 & 2.568 & & & 127.12 & 25.11 & 50.10 & 2.570 \\ DJ11-23 & 127.58 & 25.00 & 49.96 & 2.605 & & & 128.20 & 25.10 & 50.15 & 2.659 \\ DJ11-24 & 128.14 & 25.03 & 50.03 & 2.606 & & & 129.09 & 24.97 & 50.19 & 2.608 \\ DJ11-25 & 127.33 & 25.06 & 50.02 & 2.587 & & & 128.07 & 25.12 & 50.07 & 2.591 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Basic physical parameters of sandstone specimens. Figure 2: Change of the density of sandstone after solution corrosion. the sandstone was close to saturation. It can be seen that the hydrochemical corrosion of sandstone has a time effect. The hydrochemical corrosion process of sandstone must be accompanied by the change of some macroscopic physical parameters, among which the significant phenomenon is that the mass of the sandstone specimen changes with the change of corrosion time. Additionally, the mass change of sandstone specimens in the corrosion process is often compared and analyzed with the mass increase rate as a measurement index, which can be calculated as shown in Equation (1). \[\mathrm{W}(t)=(\mathrm{m}_{t}-\mathrm{m})/\mathrm{m} \tag{1}\]  
where \(\mathrm{W}(t)\) represents the sandstone specimen after corrosion by strong alkali solution mass increase rate, %; \(\mathrm{m}_{t}\) and \(\mathrm{m}\) are sandstone specimen corrosion times \(t\) after and not corrosive mass.