## 4 Conclusions  
In the present work, a new approach was proposed to encapsulate mono- and divalent cations in glass ceramics derived from alkali-activated brick. Cations were initially bound to alkali-brick at room temperature, and the resulting material was heated at different temperatures and analyzed. The combined use of XRD, ESEM/EDS, and TGA/DSC revealed noticeable chemical, textural, and morphological transformations of alkali-brick. These transformations took place at successive temperature stages: first, at temperatures up to 400 \({}^{\circ}\)C, the dehydration of illite and zeolites occurred; second, at temperatures between 400 \({}^{\circ}\)C and 700 \({}^{\circ}\)C, the dehydroxylation of illite occurred, followed by its decomposition; third, at 800-1000 \({}^{\circ}\)C, the degradation of zeolites NaA and NaP into other aluminosilicates, identified as analcine-derived solid solutions and mullite, occurred; and fourth, at T \(\geq\) 1000 \({}^{\circ}\)C, sand melted, contributing strongly to the formation of glass ceramics. Owing to the input of silica from the melted sand, the glassy-silica content increased in the heated brick, improving the chemical durability of the calcined material and assuring the coating of (thermally formed-) crystalline aluminosilicate minerals and radio-element encapsulation.  
Moreover, our investigations allowed us to obtain information about the corrosion resistance of thermally treated-alkali-brick aggregates under highly aggressive acid conditions. This research provides evidence of the importance of the degradation and chemical transformation of illite and zeolites Na-A and Na-P and the melting of sand regarding the chemical durability of the material. Thus, leaching tests carried out on calcined-brick samples evidenced the efficient barrier properties of the glass matrix toward (trapped) crystalline aluminosilicate structures containing either mono-valent cations (Na\({}^{+}\), K\({}^{+}\), Cs\({}^{+}\)) or divalent cations (Co\({}^{2+}\), Sr\({}^{2+}\)).  
Globally, this work provides novel ideas for the encapsulation of radioactive elements from nuclear liquid waste by using brick aggregates as low-cost starting materials. The challenges and prospects of employing zeolite-geo-polymeric composites derived from  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Heating Temperature** & **90 \({}^{\circ}\)C** & **600 \({}^{\circ}\)C** & **800 \({}^{\circ}\)C** & **900 \({}^{\circ}\)C** & **1000 \({}^{\circ}\)C** \\ \hline BET surface area (S\({}_{\text{BIFI}}\)) in m\({}^{2}\)/g & 19.319 & 14.421 & 4.254 & 0.801 & 0.002(6) \\ \hline Single point adsorption total pore volume of pores & & & & & \\ (\(\varnothing\) \(<\) 313.549 nm at P/P\(\varnothing\)\(\leq\) 0.9942) in cm\({}^{3}\)/g & 0.0397 & 0.0353 & 0.0200 & 0.0031 &
\begin{tabular}{c} 0.0017 (at \\ P/P\(\varnothing\)\(\leq\) 0.2716) \\ \end{tabular} (\(\varnothing\) \(<\) 313.549 nm at P/P\(\varnothing\)\(\leq\) 0.9942) in cm\({}^{3}\)/g & 0.0363 & 0.0323 & 0.0205 & 0.0028 & - \\ \hline Adsorption average pore width (4 V/A by BET) in nm & 8.22 & 9.78 & 18.80 & 15.53 & - \\ \hline BJH Adsorption average pore diameter (4 V/A) in nm & 12.71 & 13.45 & 17.30 & 27.52 & - \\ \hline BJH Desorption average pore diameter (4 V/A) in nm & 12.46 & 13.23 & 16.16 & 28.58 & - \\ \hline \end{tabular}
\end{table}
Table 2: Micro-porosity of alkali-activated brick after thermal treatment at 90 \({}^{\circ}\)C, 600 \({}^{\circ}\)C, 800 \({}^{\circ}\)C, 900 \({}^{\circ}\)C, 900 \({}^{\circ}\)C, 900 \({}^{\circ}\)C, and 1000 \({}^{\circ}\)C for 1 day.  
brick will open novel avenues of research, i.e., exploring the development of these materials as industrial (low-cost) byproducts to address issues of radioactive contamination.