## 3 Results and Discussion
### Clinker Characterization
#### 3.2.5. Cement Physical Property  
The flexural and compressive strengths of nine types of cement cured for 3 and 28 days are presented in Table 6. According to China's national standard GB/T 175-2023, the flexural and compressive strengths of 52.5 Portland cement at 3 and 28 days of curing are 4.5 MPa and 22.0 MPa, and 7.0 MPa and 52.5 MPa, respectively. As shown in Table 6, within the same curing period, the addition of biomass alternative fuels led to a decrease in the 3-day flexural and compressive strength of the cement, Notably, this effect is particularly pronounced in the cement samples mixed with corncob alternative fuel. As the substitution ratio increases, the flexural strength after three days decreases by approximately 5%. However, after 28 days of curing, the flexural and compressive strengths were comparable to those of the cement without biomass fuel ash. Based on the conclusions drawn in the previous chapter of this study, on the one hand, high alkali content hinders the formation of C\({}_{3}\)S. On the other hand, when biomass alternative fuels are incorporated, some intermediate products, such as CaSiO\({}_{3}\) formed during calcination, cannot be fully converted into C\({}_{3}\)S or C\({}_{2}\)S. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**Flexural Strength (MPa)**} & \multicolumn{2}{c}{**Compressive Strength (MPa)**} \\ \cline{2-5}  & **3 d** & **28 d** & **3 d** & **28 d** \\ \hline H\({}_{0}\) & 6.73 & 8.58 & 35.17 & 60.88 \\ H\({}_{\text{DCI}}\) & 6.62 & 8.55 & 34.63 & 60.86 \\ H\({}_{\text{DG2}}\) & 6.53 & 8.53 & 34.51 & 60.84 \\ H\({}_{\text{YMX1}}\) & 6.47 & 8.54 & 34.23 & 61.09 \\ H\({}_{\text{MX2}}\) & 6.41 & 8.54 & 34.11 & 60.90 \\ H\({}_{\text{HM1}}\) & 6.70 & 8.55 & 34.70 & 60.85 \\ H\({}_{\text{JM2}}\) & 6.68 & 8.55 & 34.55 & 60.79 \\ H\({}_{\text{SY1}}\) & 6.64 & 8.55 & 34.50 & 60.85 \\ H\({}_{\text{SY2}}\) & 6.62 & 8.55 & 34.48 & 60.86 \\ \hline \hline \end{tabular} (1)  
As shown in Table 6, within the same curing period, the addition of biomass alternative fuels led to a decrease in the 3-day flexural and compressive strength of the cement, Notably, this effect is particularly pronounced in the cement samples mixed with corncob alternative fuel. As the substitution ratio increases, the flexural strength after three days decreases by approximately 5%. However, after 28 days of curing, the flexural and compressive strengths were comparable to those of the cement without biomass fuel ash. Based on the conclusions drawn in the previous chapter of this study, on the one hand, high alkali content hinders the formation of C\({}_{3}\)S. On the other hand, when biomass alternative fuels are incorporated, some intermediate products, such as CaSiO\({}_{3}\) formed during calcination, cannot be fully converted into C\({}_{3}\)S or C\({}_{2}\)S.  
\end{table} 
Table 6: Mechanical properties of cement samples at different ages. This observation aligns well with the results obtained from the aforementioned clinker XRD analysis. These minerals, which are crucial for providing cement strength in the middle and late stages, exhibit a slower hydration rate in the early stage. However, after 28 days of continuous hydration, the primary hydration products (e.g., C-S-H gel and Ca(OH)2) stabilize, compensating for the lack of early strength. This further demonstrates that the ash deposited by biomass fuels at lower substitution ratios has a negligible impact on the long-term performance of clinker;
2. The setting time, standard consistency, specific surface area, and stability are key indicators for assessing the physical properties of cement [58]. As shown in Table 7, the incorporation of biofuel ash reduces the initial setting time of cement, the maximum reduction observed is 13 min. The effect on the final setting time is relatively minor. Furthermore, as the blending ratio of biomass alternative fuels increases, the standard consistency of the cement paste also increases.