## 1 Introduction
Its accessibility and low cost have motivated researchers to assess the possible use of brick aggregates as adsorbents (after coating with ferrihydrite) to remove inorganic and organic contaminants from wastewaters, e.g., (i) iron(II) present in anoxic (ferrous) groundwaters [43; 44]; (ii) metallic pollutants such as Cu\({}^{2+}\), Cd\({}^{2+}\), Pb\({}^{2+}\), and Zn\({}^{2+}\)[45; 46; 47; 48]; and (iii) endocrine-disrupting chemicals, such as bisphenol A (BPA) and 4-nonyl phenol (NP), as well as hormones (17\(\alpha\)-ethynylestradiol, testosterone, and estrone) [49; 50]. Moreover, alkali-activated brick was also tested as an ion exchanger. To that end, the alkaline activation of raw brick was undertaken thermally with sodium hydroxide, bringing about a series of chemical reactions (geo-polymerization, followed by zeotilization), and leading, with time, to the formation of zeolite-based composites [51; 52]. In these composites, the presence of negative charges carried by [AlO\({}_{4}\)]\({}^{-}\) tetrahedra in zeolites enabled the binding of various cations such as alkali (Li, K, Na, Cs, Rb), transition-alkaline-earth (Sr), or transition metals (Co, Fe, Mn, Zn, Cu, Ni, Cd) [53; 54; 55; 56]. However, as cationic species still remained chemically unfixed to the brick matrix in the form of hydrates/complexes, these could easily be desorbed, e.g., when the brick grains came into contact with concentrated NaCl and/or NaOH solutions [53; 54]. Fortunately, our recent work has revealed the possibility of the effective immobilization of adsorbed cationic species by thermal treatment of brick pellets [57]. Moreover, according to some authors [58; 59], geo-polymer-zeolite composites may be converted progressively into aluminosilicate ceramic forms after exposure to elevated temperatures. As alkali-activatedbrick was assimilated to a geo-polymer / zeolites/sand composite [51; 52], it would not be surprising if similar thermal transformations occurred with such a material, resulting in further enhancement of the ability to immobilize radio-elements. Owing to the beneficial characteristics of brick material (thermal and physical stability, easy processing) and its negligible environmental impact, it may offer favorable conditions for the safe disposal of radio-elements derived from radioactive nuclear liquid wastes under thermal treatment [52; 57]. However, in order to achieve more practical applications, it was necessary to improve and optimize existing immobilization methods. In particular, the influence of the calcination temperature on brick activated by sodium hydroxide was still unclear. Hence, related studies needed to be conducted with the aim of better understanding the chemical/structural evolution of alkali-brick with temperature and the effects of the obtained matrix on the extent of adsorbate stabilization. From these perspectives, there was an urgent need to clarify the mechanisms involved after each thermal step. In the present work, we explored the possibility of using a type of brick composed mainly of sand, metakaolin, and illite to synthesize creamized-brick materials. We sought to prepare these materials under simple operational conditions and to achieve suitable radionuclide immobilization performance and long-term stability. To accomplish this, the alkali activation of raw brick with NaOH had to be undertaken with the aim of generating zeolites Na-A and Na-P through metakaolin zeolitization [52; 57]. The presence of zeolites in alkali-brick (having crystalline aluminosilicate materials with Si and Al tetrahedrons and counter cations (Na\({}^{+}\)) in extra-frameworks) would make it possible to increase the ion-exchange properties of the composite, and hence, to enable the fixation of radioactive cations such as Cs\({}^{+}\), Rb\({}^{+}\), Co\({}^{2+}\), or Sr\({}^{2+}\) to the negatively charged sites present in zeolitic frameworks.