C reactions are slow, so it’s only with time that resistance increases. Such behavior is associated towards the formation of calcium silicate hydrate (CSH) resulting from the reaction involving calcined kaolin residue and portlandite, i.e., a pozzolanic reaction. As expected, the CSH formation increases the mechanical strength. For cure times 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 100 ). In the point of view of mechanical strength, this outcome Tasisulam manufacturer indicates that the kaolin residue, calcined Sustainability 2021, 13, x FOR PEER Assessment 7 of 16 at 800 C, has the possible to replace cement in mortar. All IPA values had been larger than the minimum limit of 75 recommended by ASTM C618 [36].Figure 4. 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 soon after Aging in Internal and External Environments 3.two. Mortar Properties just after Aging in Internal and External Environments Figure 5a shows XRD patterns of mortar KR 800 C aged under internal environFigure 5a shows XRD patterns of mortar KR 800 aged beneath 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 GS-626510 In Vivo quartz (SiO2, JCPDS 46-1045) were phases identified within the mortars exposed for the internal and external environment. Having said that, the intensity on the portlandite phase peaks decreasedFigure 4. The compressive strength and pozzolanic activity index values for mortar ref. and mortar KR 800 samples.Sustainability 2021, 13,three.two. Mortar Properties 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)2, JCPDS 72-0156); ettringite 360 and 2O3 days (Figure 5d ). The portlandite (Ca(OH)two JCPDS 05-0586); and quartz (3CaO.Al512.3CaSO4.32H2O, JCPDS 72-0646); calcite (CaCO3, , JCPDS 72-0156); ettringite (3CaO Al2 O46-1045) have been phasesJCPDS 72-0646); calcite (CaCO3 , JCPDS 05-0586); and (SiO2, JCPDS 3 3CaSO4 32H2 O, identified inside the mortars exposed to the internal and quartz (SiO2 , JCPDS 46-1045) have been phases identified in the mortars exposed to decreased external environment. On the other hand, the intensity of the portlandite phase peaksthe internal and time. Such behavior Even so, the intensity in the portlandite phase peaks carbonawith external environment.is strongly associated for the pozzolanic reactions and thedecreased withprocess. This indicates that the pozzolanic reaction and the carbonation method, over tion time. Such behavior is strongly associated for the pozzolanic reactions plus the carbonation method. This indicates that the pozzolanic reaction as well as the carbonation process, as time passes, 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.