## 5 Micro-Properties of the Cemertitious Materials with RP
### Pore Structure
[32] reported that by reducing the size of RCP particles from 36.1 \(\upmu\)m to 3.0 \(\upmu\)m, the critical pore size of cement pastes reduces significantly from 277 nm to 60 nm. They observed that when the particle size exceeded 13.1 \(\upmu\)m, RCP fractions had an equal ability to refine the pores of cement pastes in the later stage. [PERSON] et al. [245] stated that substituting 30% of cement with RP increases the size of the pores and the porosity of the paste. However, when an active mineral admixture is added to the RP blended paste, it refines the pore structure. The refinement of the pore structure is more noticeable when metakaolin (MK) or SF is added to the mix. [PERSON] et al. [217] observed that the inclusion of NS resulted in a noticeable reduction in porosity. Figure 17: Pore volume fraction (%) versus pore sizes (nm) for mechanically treated RP utilized in cement-based materials [32, 71, 296]. [PERSON] et al. [145] reported that pastes including lime, FA, or slag exhibited an increase in total porosity. [PERSON] et al. [147] reported that the combination of FA and SF resulted in an increased hydration degree, leading to an improvement in the internal pore size distribution of WCRP pastes. [PERSON] et al. [140] and [PERSON] et al. [217] reported that the inclusion of NS resulted in a notable reduction in the percentage of harmful pores and a higher proportion of less harmful and harmless pores. Additionally, it was shown that NS had a beneficial influence on pore refinement. The incorporation of RP increases the pore size of alkali-activated paste blended with RP [133; 216; 229; 231] as presented in Figures 18 and 19. An alkaline environment promotes the disruption and rearrangement of silicon-aluminum glass components, the formation of cement-like materials, and the filling of pores in the RP material [216; 229; 231]. Figure 19: Pore volume fraction (%) versus pore sizes (nm) for alkali-activated cement-based materials with different RP percentages [228; 293]. Figure 18: Porosity variation (%) in alkali-activated cement-based materials with different RP percentages (%) [205; 216; 228]. Subjecting RP to thermal activation enhances porous microstructure in cementitious materials, and consequently the pore size, pore volume, and porosity become refined [8; 52; 97; 101; 211; 231; 250; 252; 256; 294], as presented in Figures 20-22. Figure 21: Average pore diameter (mm) of thermally activated RP utilized in cement-based materials versus temperature (\({}^{\circ}\)C) [8; 101; 250; 256]. Figure 20: Porosity variation (%) in thermally activated RP utilized in cement-based materials versus temperature (\({}^{\circ}\)C) [8; 101; 256]. [PERSON] et al. [52] argued that the internal composition of the mortar exhibits the highest level of structural integrity after being subjected to heat treatment at 800 \({}^{\circ}\)C. [PERSON] et al. [97] stated that following the inclusion of the RP, the dimensions of the capillary pores experienced slight enlargement, from 237 to 278 nm. Significantly, the critical pore size of RAAC decreased to 107 nm after the RP was calcined at 600 \({}^{\circ}\)C.  
[PERSON] et al. [250] reported that untreated WCP-20C (30%) increases the pore size and porosity of the paste it is used in. When the temperature at which thermal activation occurs on WCP is between 600 \({}^{\circ}\)C and 1000 \({}^{\circ}\)C, the pore size and porosity of the paste containing activated WCP are lower compared to the paste containing unactivated WCP. They also stated that the inclusion of waste powder following activation at 1200 \({}^{\circ}\)C has a detrimental impact on the pore structure of the newly formed paste due to its inferior nucleation action and filler effect. [PERSON] et al. [255] reported that the harmless and less harmful pore volume in paste containing 10% RCP-20C are lower than in plain paste, whereas the harmless pore volume and less harmful pore volume in paste containing 50% RCP-20C are higher than in the original paste.