C reactions are slow, so it can be only with time that resistance increases. Such behavior is connected for the formation of calcium silicate hydrate (CSH) resulting in the reaction amongst calcined kaolin residue and portlandite, i.e., a pozzolanic reaction. As anticipated, the CSH formation increases the mechanical strength. For cure instances equal to 14 and 28 days, the mortar KR 800 C sample showed slight CS values than the samples measured for the mortar ref. (IPA one hundred ). In the point of view of mechanical strength, this outcome indicates that the kaolin residue, calcined Sustainability 2021, 13, x FOR PEER Overview 7 of 16 at 800 C, has the potential to replace cement in mortar. All IPA values have been higher than the minimum limit of 75 suggested by ASTM C618 [36].Figure four. The compressive strength and pozzolanic activity index values for mortar ref. and mortar Figure four. The compressive strength and pozzolanic activity index values for mortar ref. and mortar KR 800 samples. KR 800 C samples.3.two. Mortar Properties immediately after Aging in ML-SA1 Epigenetics internal and External Environments 3.2. Mortar Properties just after Aging in Internal and External Environments Figure 5a shows XRD patterns of mortar KR 800 C aged beneath internal environFigure 5a shows XRD patterns of mortar KR 800 aged below internal environments (E for 30, 180, and 360 days (Figures 5a ) and external environments (Ee for for ments (Ei)i ) for 30, 180, and 360 days (Figure 5a ) and external environments) (Ee )and 512 days (Figures 5d ). The portlandite (Ca(OH)two, JCPDS 72-0156); ettringite (3CaO.Al2O3.3CaSO4.32H2O, JCPDS 72-0646); calcite (CaCO3, JCPDS 05-0586); and quartz (SiO2, JCPDS 46-1045) were phases identified in the mortars exposed towards the internal and external environment. Nonetheless, the intensity of the portlandite phase peaks decreasedFigure four. The compressive strength and pozzolanic activity index values for mortar ref. and mortar KR 800 samples.Sustainability 2021, 13,three.2. Mortar Properties just after Aging in Internal and External Environments7 ofFigure 5a shows XRD patterns of mortar KR 800 aged beneath internal environments (Ei) for 30, 180, and 360 days (Figures 5a ) and external environments (Ee) for 360 and 512 days (Figures 5d ). The portlandite (Ca(OH)two, JCPDS 72-0156); ettringite 360 and 2O3 days (Figure 5d ). The portlandite (Ca(OH)2 JCPDS 05-0586); and quartz (3CaO.Al512.3CaSO4.32H2O, JCPDS 72-0646); calcite (CaCO3, , JCPDS 72-0156); ettringite (3CaO Al2 O46-1045) were phasesJCPDS 72-0646); calcite (CaCO3 , JCPDS 05-0586); and (SiO2, JCPDS 3 3CaSO4 32H2 O, identified in the mortars exposed towards the internal and quartz (SiO2 , JCPDS 46-1045) had been phases identified within the mortars exposed to decreased external atmosphere. Having said that, the intensity of your portlandite phase peaksthe internal and time. Such behavior Nonetheless, the intensity in the portlandite phase peaks carbonawith external atmosphere.is IQP-0528 Autophagy strongly related towards the pozzolanic reactions and thedecreased withprocess. This indicates that the pozzolanic reaction and also the carbonation method, over tion time. Such behavior is strongly related towards the pozzolanic reactions plus the carbonation method. This indicates that the pozzolanic reaction and also the carbonation process, over time, time, have consumed the portlandite. have consumed the portlandite.30 daysM30-Ei E P E P M20-Ei E P M15-Ei E P M10-Ei E P M5-Ei E P E E Q C E Q C C E C E C E Q Q E C Q E C E Q C E Q C E Q E C E Q C C E(a)Q180 daysM30-EiC E C E(b)QM30-Ei360 days P E C P E C.