## 4 Activation Methods of RP
The surface cracks expanded as the treatment temperature was increased to 800 \({}^{\circ}\)C. They also observed particle aggregation after thermal treatment. They stated that the BET surface area exhibited a significant decrease as the temperature of thermal treatment increased, and the size of the agglomerated particles in WCP/TWCP powders likewise increased as the temperature increased. In general, an increase in temperature during the thermal treatment of RP results in a noticeable alteration in the size of the particles as presented in Figure 11. In some of the studies, the particle size of RP after thermal activation increases because of the displacement of chemically and physically bonded water that tends to aggregate, which causes the agglomeration during the thermal treatment process [8,52,132,250,255]. However, for the RP treated at low temperatures (400 \({}^{\circ}\)C and 600 \({}^{\circ}\)C), no significant difference was observed, indicating that it has a low propensity for agglomeration [8,52,250,255]. The samples that underwent treatment at elevated temperatures (800 \({}^{\circ}\)C) experienced volume expansion because of the transition from \(\alpha\)- to \(\beta\)-quartz, which led to the formation of comparatively sizable particles [8,52,132,250]. When the activation temperature is over 800 \({}^{\circ}\)C, the particle size of RP tends to decrease [8; 215; 250]. In some of the other studies, the particle size of RP after thermal activation decreases, especially over 400 \({}^{\circ}\)C [174; 215]. Regarding the effect of thermal activation on the minerology of RP, based on the experimental results observed, varying temperatures have distinct effects on the minerology of RP [8; 52; 95; 97; 101; 132; 179; 215; 231; 247; 250; 253; 255; 256]  
[PERSON] et al. [52] observed quartz, calcite, and gismodine after thermal treatment but not dolomite, which was observed after mechanical treatment. Additionally, new active materials such as larnite and calcium silicates (Ca\({}_{3}\)SiO\({}_{5}\) and Ca\({}_{2}\)SiO\({}_{4}\)) were detected following thermal activation temperatures of 400-600 \({}^{\circ}\)C. They stated that at a thermal activation temperature of 800 \({}^{\circ}\)C, the calcite present in RCP undergoes decomposition, resulting in the formation of CaO and CO\({}_{2}\). In addition, they stated that the intensity of the diffraction peak in quartz is lower compared to the 400-600 \({}^{\circ}\)C RCP spectrum, which suggests that the amount of crystalline SiO\({}_{2}\) decreases while the amount of amorphous SiO\({}_{2}\) increases, which may be attributed to the crystalline transition of \(\alpha\)-SiO\({}_{2}\) at temperatures ranging from 600 to 800 \({}^{\circ}\)C.  
[PERSON] et al. [231] utilized chemical, thermal (500 \({}^{\circ}\)C, 600 \({}^{\circ}\)C, 700 \({}^{\circ}\)C, 800 \({}^{\circ}\)C, and 900 \({}^{\circ}\)C), and combined chemical-thermal activation to stimulate the activity of RFP. They reported that the CaCO\({}_{3}\) diffraction peak gradually diminished and vanished as the RFP was heated within the temperature range of 20-700 \({}^{\circ}\)C, and at temperatures over 700 \({}^{\circ}\)C, CaCO3 undergoes full decomposition. During the temperature range of 600 \({}^{\circ}\)C to 900 \({}^{\circ}\)C, distinct and ongoing diffraction peaks were detected, likely indicating the deterioration of the C-S-H gel into \(\beta\)-C\({}_{2}\)S due to thermal activation. Furthermore, the distinctive peak of \(\beta\)-C\({}_{2}\)S became increasingly sharper as the temperature increased to 900 \({}^{\circ}\)C, suggesting an improvement in the degree of crystallization. [PERSON] et al. [250] stated that the WCP-600 is similar in mineral composition (SiO\({}_{2}\), CaCO\({}_{3}\), and CaMg(CO\({}_{3}\))\({}_{2}\)) to the WCP-20C, with the exception that CaMg(CO\({}_{3}\))\({}_{2}\) is decomposed. They further stated that the WCP-800C, which has undergone thermal activation at 800 \({}^{\circ}\)C, can accumulate CaO composition through the disintegration of calcite.