## 3 Fundamental Properties of RP
### Mineralogical Composition  
X-ray diffraction (XRD) is commonly used to evaluate the mineralogical composition by identifying existing phases and their approximate relative content based on signal position and intensity. The mineralogical composition can be further determined using a sophisticated thermal analyzer that is capable of doing both differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) concurrently. The mineralogical composition of RP is complex because of the various mineral phases found in cement-based materials, transitioning between crystalline and amorphous states [9; 38; 52; 122]. The identified primary common compounds include the following: quartz (SiO\({}_{2}\)) [7; 35; 45; 52; 67; 78; 82; 83; 84; 92; 98; 118; 120; 122; 127; 128; 152; 153; 168; 173; 178; 191; 192; 194; 195; 203; 204; 208; 218; 225; 232; 233; 234; 235], calcite (CaCO\({}_{3}\)) [32; 35; 45; 52; 56; 67; 73; 78; 82; 84; 92; 98; 116; 118; 120; 122; 127; 128; 153; 168; 173; 178; 191; 192; 194; 195; 203; 204; 208; 218; 225; 232; 234; 235], portlandite (CaOH)\({}_{2}\) or CH) [32; 56; 67; 82; 92; 98; 152; 153; 195; 203; 204; 233], dolomite (CaMg(CO\({}_{3}\))\({}_{2}\)) [32; 52; 83; 127; 168; 192; 194; 218; 232], albite (NaNiSi\({}_{3}\)O) [45; 98; 128; 194; 208; 218], belite, (dicalcium silicate, C\({}_{2}\)S) [56; 67; 78; 82; 147; 152; 232], alite, (tricalcium silicate, C\({}_{3}\)S) [7; 67; 78; 82; 147; 152], potassium or sodium feldspar [78; 118; 152; 168; 191; 218], C-S-H gel [35; 56; 67; 73; 78; 82; 92; 118; 120; 147; 153], ettringite (Aft) [56; 82; 92; 98; 118; 120], tobermorite [73; 173], gismodine [52; 83; 120; 204], gypsum [82; 98], muscovite [128; 152], celite [82], ferrite [82], anothite [233], monosulfate [82], margarite [120], mica [118], zeolite [82], larnitte [82], chlorite [152], and hedenbergite [203]. The presence of quartz and albite phases in RP can be attributed to the sand and gravel particles found in WC [45; 52; 67; 98; 122; 127; 153; 192; 225; 235]. The presence of calcite in RP is likely attributed to the carbonation process of the original concrete [98; 122; 127; 218; 225; 233; 235]. Portlandite, ettringite (AFt), Ca-based anothite, and gypsum originated from cement or the primary hydration products of cement [98; 233] The hydrated compounds CH and C-S-H gel were formed because of the solidification of the cement paste [67]. C\({}_{2}\)S and C\({}_{3}\)S were derived from the unhydrated cement particles in the hardened cement [67]. The primary origin of dolomite is the limestone coarse aggregate present in the initial concrete [192]. In some of the studies, the XRD spectrum does not show the presence of hydration products often found in hardened paste, such as AFt and CH [45; 52; 178; 153; 178]. This suggests that the portlandite and ettringite encountered decomposition or carbonization [45; 52; 153; 218]. [PERSON] et al. [218] and [PERSON] et al. [194] argued that the reason for the relatively low CH content is the high alkalinity of RCP, which facilitates the carbonation of CH in RCP. Furthermore, they stated that the large surface area of RCP allows for greater contact between CH and air. Additionally, CH undergoes carbonization during the synthesis of RCP. The low content of ettringite can be attributed to its breakdown caused by the rise in temperature during RCP grinding [218]. Regarding the grinding time, [PERSON] et al. [82] reported that as the number of recycling cycles expands, the intensity of the portlandite becomes more pronounced, while the intensity of quartz diminishes. They stated that this is primarily caused by the adjustment of the mixed proportion of the parent concrete, which is influenced by the larger amount of adhering mortar carried by the RCA. [PERSON] and [PERSON] [232] reported that the crystallization peak of the recycled fine powder (RFP), after being subjected to ball mill grinding for 10 min, is lower compared to the untreated RFP.