## 3 Results
### Magnetic Susceptibility of Some Construction Materials for Pavilions
#### 3.1.2 Concrete Magnetization Due to Its Solidification  
The phenomenon described in this subsection is probably the most significant challenge one has to face during magnetic observatory installation. In terms of collaboration between the Geophysical Center of RAS and the Institute of Geosphere Dynamics of RAS, it was planned to install a full observatory set of magnetometers on the territory of the Mikhnevo geophysical observatory (Moscow region). In 2019, the place for the pavilions was selected as a result of two magnetic survey series. Later in 2019, during the development of the construction project, we made the magnetic susceptibility measurements on concrete mix samples for future pillar feet. Three series of measurements were carried out using PIMV. The resulting magnetic susceptibility values were about 7.2-7.3 \(\times\) 10\({}^{-5}\) SI, which meant that the mix belonged to very weakly magnetized building materials and was suitable for the footing construction. To avoid the magnetic effects from possible concrete mix contamination due to ferromagnetic materials or minerals, we used \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Specimen** & **Weight, g** & **\(\kappa\), \(\times\)10\({}^{-5}\) SI** & **Conclusion** \\ \hline \hline \multicolumn{1}{c}{Pumice block} & \(\approx\)30–40 & 23 & Very low magnetization \\ Mineral wool & 3.5 & 8.562 & Very low magnetization \\ Plastic envelope & 15.2 & 2.45 & Very low magnetization \\ Channel bar fragment & 6.3 & 0.6159 & Very low magnetization \\ Profile for a window frame & - & 0 & Very low magnetization \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Magnetic properties of some construction materials for the Gyulagarak observatory. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Material** & **Measurement No.** & \(\kappa\) (**L v.)**, & \(\kappa\) (**s. v.)**, & **Correction Factor** & **Total \(\kappa_{\
u}\) \(\times\)10\({}^{-5}\) SI Units** & **Conclusion** \\  & & \(\times\)10\({}^{-5}\) SI Units, & \(\times\)10\({}^{-5}\) SI Units & **Correction Factor** & **Total \(\kappa_{\
u}\) \(\times\)10\({}^{-5}\) SI Units** & **Conclusion** \\ \hline \multirow{4}{*}{Solidified glue, chipped off the pillars} & 1 & 4.631 & 3.852 & 1.4 & 5.3928 \\  & 2 & 11.74 & 3.248 & 1.4 & 4.5472 \\  & 3 & & 2.582 & 1.4 & 3.6148 \\  & 4 & & 2.21 & 1.4 & 3.094 \\  & 5 & & 4.191 & 1.4 & 5.8674 \\ \hline \multirow{4}{*}{The same solidified glue, a single piece} & 1 & 5.733 & 0 & 1.4 & data \\  & 2 & 3.91 & 0 & 1.4 & \\  & 3 & 4.837 & 0 & 1.4 & \\  & 4 & 4.121 & 0 & 1.4 & \\  & 5 & 4.509 & 0 & 1.4 & data \\ \hline \multirow{4}{*}{The same glue (loose, in a plastic jar)} & 1 & 6.136 & 3.125 & 1.4 & 4.375 \\  & 2 & 6.068 & 3.143 & 1.4 & 4.4002 \\  & 3 & 6.366 & 2.949 & 1.4 & 4.1286 \\  & 4 & 6.175 & 2.374 & 1.4 & 3.3236 \\  & 5 & 6.685 & 3.765 & 1.4 & 5.271 \\ \hline \multirow{4}{*}{Akfix polyurethane (liquid, a plastic tube)} & 1 & 0 & 1.4 & - & - \\  & 2 & 0 & 1.4 & - & Very low \\  & 3 & 0 & 1.4 & - & magnetization \\  & 4 & 0 & & 1.4 & - \\  & 5 & 0 & & 1.4 & - \\ \hline \multirow{4}{*}{Akfix polyurethane (solidified) glue (solidified)} & 1 & 0 & 1.4 & - & \\  & 2 & 0 & 1.4 & - & Very low \\ \cline{1-1}  & 3 & 0 & 1.4 & - & magnetization \\ \cline{1-1}  & 4 & 0 & 1.4 & - & \\ \cline{1-1}  & 5 & 0 & 1.4 & - & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Magnetic susceptibility of glue used for construction of pavilions and pillars at the Gyulagarak observatory. the same pillar design as those used at the Klimovskaya and Gyulagarak observatories (1.4-1.5 m glass block pillar mounted on a concrete monolithic part). Therefore, when the feet for pavilions were constructed, their tops were right at the floor level. In spring 2021, the pavilions were finished except for the glass parts of the pillars, and we decided to carry out a magnetic survey inside both pavilions in order to find possible sources of artificial magnetic anomalies.