## 3 Results
### Thermo-Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC)  
Thermal properties of alkali-activated brick were explored using TGA/DSC techniques, as depicted in Figure 2.  
The TGA curve displayed multiple mass losses throughout successive temperature ranges. As the brick material was subjected to increasing temperatures, different observed thermal events occurred due to the physical and chemical processes taking place within brick framework. The initial \(\sim\)1.2% weight loss took place in the temperature interval 25-150 \({}^{\circ}\)C (Figure 2). This weight loss resulted from the removal of surface water or water molecules which were weakly attached to the brick minerals. The second (weaker)  
Figure 2: Thermo-Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) performed on aggregates of alkali-activated brick. The arrow indicates the temperature at which \(\alpha\)-to-\(\beta\) quartz transition took place. The vertical dash lines represent the temperature range at which the DSC thermal event characteristic of illite dehydroxylation occurred.  
weight loss, amounting to around 0.6%, was observed within the temperature range of 150 \({}^{\circ}\)C to 400 \({}^{\circ}\)C. This mass drop likely resulted from the removal or desorption of crystalline water molecules which were enclosed/trapped in the zeolitic and illicit brick frameworks. On the DSC graph, endothermic stages spreading from 80 \({}^{\circ}\)C to around 400 \({}^{\circ}\)C were thermodynamically representative of the physical processes of water extraction from brick minerals. Note that these two dehydration steps were found to be similar to those previously detected by TGA and DSC for illite [62] and zeolites Na-A and Na-P [63] by analyzing them separately. As the temperature increased, another weight drop (about 1.3 w%) was detected, and the TGA profile comprised: (i) a first step, starting at 400 \({}^{\circ}\)C and finishing at around 550 \({}^{\circ}\)C; and (ii) a second (very weak) step, spreading from ~550 \({}^{\circ}\)C to ~700 \({}^{\circ}\)C (Figure 2). The global profile was found to be comparable to that previously observed for Hungarian white illite [62]. The two TGA steps observed in the temperature interval 400-700 \({}^{\circ}\)C were attributed to the weight drop resulting from the dehydroxylation of illite. Indeed, in the 400-700 \({}^{\circ}\)C temperature range (at which illite is dehydroxylated), no weight loss was observed by TGA when analyzing quartz separately [64; 65], zeolite Na-A [66] or zeolite Na-P [63] (given that all these compounds represent grossly brick minerals). Beyond 700 \({}^{\circ}\)C, TGA analysis revealed no significant weight loss (see Figure 2). This was expected, as no weight loss was detected in the different TGA curves of the major brick minerals if these were thermally analyzed individually, i.e., illite [62], zeolite Na-A [66], zeolite Na-P [63], and quartz [64; 65]. Globally, a total weight loss of 3.1 w%, measured by TGA analysis, represented successive losses of water and illicit hydroxyls.  
On the DSC graph (Figure 2), one may observe: (i) one sharp exothermic peak at 573 \({}^{\circ}\)C, corresponding to the \(\alpha\rightarrow\beta\) phase transition of quartz [67]; (ii) a broad DSC thermal profile in the 400-700 \({}^{\circ}\)C temperature interval (comparable to that observed by [PERSON] and co-workers [62]), caused by illite dehydroxylation; and (iii) beyond 700 \({}^{\circ}\)C a succession of endothermic stages showing that the investigated sample had undergone structural/chemical transformations and phase transitions accompanied by glass formation.