## 4 Activation Methods of RP  
A constraining factor in the utilization of RP as a pozzolanic in cement-based materials is their relatively low reactivity in comparison to PC. The current and most common methods to overcome this issue include mechanical, thermal, CO\({}_{2}\)-curing, chemical, and biomineralization (2004; 2005; 2006; 2007; 2008; 2009; 2009; 2010; 2011; 2012; 2013; 2014; 2015; 2016; 2017; 2018; 2019; 2020; 2021; 2022; 2023; 2024; 2025; 2026  
of 600-800 \({}^{\circ}\)C is recommended for thermal activation to enhance the qualities of WCP, while considering energy consumption and thermal activation efficiency. [PERSON] et al. [247] examined RCFs, which are activated through a thermal treatment (500 \({}^{\circ}\)C, 800 \({}^{\circ}\)C, and 1100 \({}^{\circ}\)C) method. They observed that the particle size distribution of the RCFs is not appreciably affected by thermal treatment. On the other hand, the densities of the RCFs increase as the thermal treatment temperature increases, reaching a maximum at 800 \({}^{\circ}\)C, which is a result of the evaporation of water that is both physically and chemically attached to the substance during the process of thermal treatment. [PERSON] et al. [255] utilized thermal treatment for 300 \({}^{\circ}\)C, 600 \({}^{\circ}\)C, and 800 \({}^{\circ}\)C on fire-damaged concrete waste. They reported that the microstructure of RCP-20C exhibits irregularity, and it is possible to observe the C-S-H gel. At a temperature of 300 \({}^{\circ}\)C, the cotton-like and porous micro-structure of RCP-300C transforms into a compact microstructure due to the disintegration of C-S-H gel. At a temperature of 800 \({}^{\circ}\)C, the microstructure of RCP-800C becomes more compact compared to RCP-20C due to the disintegration of portlandite and calcite. The study of [PERSON] et al. [215] focused on the process of hydrating and reusing WCP after a thermal treatment within a temperature range of 400 \({}^{\circ}\)C to 800 \({}^{\circ}\)C. They observed that heating WCP to 600 \({}^{\circ}\)C resulted in the formation of large cluster structures. Following a 700 \({}^{\circ}\)C treatment, the presence of small clusters was noticeable. Additionally, the size of the WCP heated to 800 \({}^{\circ}\)C was larger than that of the WCP heated to 700\({}^{\circ}\)C, but smaller than that of the WCP heated to 600 \({}^{\circ}\)C. The surfaces of the WCP heated at 700 \({}^{\circ}\)C and 800 \({}^{\circ}\)C exhibited numerous holes, which were likely a result of the dehydration and recrystallization of C-S-H and the disintegration of calcium carbonate. In contrast, the WCP heated at 600 \({}^{\circ}\)C and those without thermal treatment did not show such surface changes. They concluded that WCP treated at 700 \({}^{\circ}\)C could be used in mortar or concrete as an admixture. [PERSON] et al. [8] utilized thermal modification treatment (300 \({}^{\circ}\)C, 600 \({}^{\circ}\)C, 900 \({}^{\circ}\)C, and 1200 \({}^{\circ}\)C) on WCP. They stated that at thermal modification temperatures of 300-600 \({}^{\circ}\)C, the microstructure of WCP-300C and WCP-600C becomes compact and the formation of C-S-H gel cannot be observed. However, when the activation temperature on WCP reaches 900 \({}^{\circ}\)C, new components are formed and surround the WCP-900C particle. They concluded that when using the same replacement ratio of WCP, the mortar characteristics are better when using thermally modified WCP at temperatures ranging from 600 \({}^{\circ}\)C to 900 \({}^{\circ}\)C compared to using untreated WCP. [PERSON] et al. [132] examined the impact of high temperature (600 \({}^{\circ}\)C, 700 \({}^{\circ}\)C, and 800 \({}^{\circ}\)C) on WCP and its utilization in alkali-activated materials. They stated that when exposed to temperatures of 600 \({}^{\circ}\)C, 700 \({}^{\circ}\)C, and 800 \({}^{\circ}\)C, the thermally treated waste concrete powder (TWCP) samples exhibited the formation of small fractures and flakes on their surface.