## 3 Results and Discussion
### Heat of Hydration  
Figure 6a shows the heat flow curve of the hydration heat of the paste sample over 3 days. The exothermic curve exhibits two peaks in the acceleration stage: the first peak is attributed to the rapid dissolution and hydration of C\({}_{3}\)S [44], during which the reaction mainly produces C-S-H and CH. The second exothermic peak is attributed to the reaction of the C\({}_{3}\)A hydration products with gypsum to form ettrinigite (AFt) [44; 45]. Figure 6: _Cont._An analysis of Figure 6a shows that as more QZ is added, the time when the second heat flow peak appears gradually advances [30; 46; 47]. This is because the physical effects of QZ (nucleation effect and dilution effect) accelerate cement hydration [34]. In this experiment, QZ particles smaller than 1 \(\upmu\)m are present. It is possible that QZ particles in the range of 0 to 1 \(\upmu\)m act as nucleation sites to accelerate hydration. Some scholars believe that nucleation is more evident in finer QZ [40; 48]. Figure 6b shows the experimental results of the cumulative hydration heat, revealing that as the QZ and FA content increases, the cumulative hydration heat decreases. This is primarily due to the reduction in cement content. Additionally, the low reactivity of SCMs reduces the cumulative hydration heat. Figure 6b also shows that when the amount of the mixture is the same, the cumulative hydration heat for 3 days of the sample with QZ addition is significantly higher than that of the sample with FA addition. This is because QZ accelerates the hydration reaction of cement through a more substantial physical effect, thereby generating more heat. The 3-day cumulative hydration heat of the 10 FA10 QZ group was almost the same as that of the 20 QZ group. This indicates that the accelerating effect of QZ is limited and will not continue to increase with the increase in QZ content. During the cement's dissolution and hydration reaction, heat is released, and the hydration products produced are the main reason for the increase in compressive strength [44]. Figure 6c shows the experimental results of compressive strength and cumulative hydration heat of mortar after 1 day and 3 days. The results show that the compressive strength and the cumulative hydration heat have an excellent linear relationship, with R\({}^{2}\) = 0.988. It should be noted that this linear relationship is based on the fitting of experimental data and primarily applies to early-age strength development (1 to 3 days). This is similar to the results obtained by other researchers [44]. Figure 6: Hydration heat results: (**a**) heat flow curves; (**b**) cumulative hydration heat; (**c**) relationship between the cumulative heat of hydration and the compressive strength after curing for 1 and 3 days. Figure 7a,b show the heat flow and cumulative hydration heat curves after normalizing cement mass fraction, respectively. Among these results, the cement mass fraction of sample C100 is 100%; the cement mass fraction of samples 10 FA and 10 QZ is 90%; and the cement mass fraction of samples 20 FA, 20 QZ, and 10 FA10 QZ is 80%. By studying Figure 7a, it can be observed that the C3A hydration heat peak of the sample with QZ added is higher than that of the control. According to previous studies, QZ hardly undergoes chemical reactions [22]. Therefore, this can be attributed to the nucleation and filling effects of QZ, which enhance the hydration reaction of cement. Specifically, QZ particles act as nucleation sites, promoting the formation of AFt. The reaction equation is shown in Equation (3):  
\[[\text{Al}(\text{OH})_{4}]^{-}+3(\text{SO}_{4})^{2-}+6(\text{Ca})^{2-}+\text{ aq.}\to\text{C}_{6}\text{AS}_{3}\text{H}_{32}\downarrow \tag{3}\]  
The AFt generated by the reaction can stick to the tiny QZ particles, thus accelerating its formation. Additionally, from the FTIR experimental results of the 1-day sample in Section 3.7, the group with added QZ showed stronger Al-OH absorption peaks at 1 day, indicating more AFt formation.