## 3 Results and Discussion
### Mortar Analysis
#### 3.2.2 Mortar Rheological Analysis  
According to the initial rheological properties of the mortar samples delineated in Figure 10, there is a linear relationship between shear stress and shear rate (rheometer speed). The initial shear yield stress \(\tau_{0}\) value of the mortar samples follows the order sample 6 \(<\) sample 4 \(<\) sample 3 \(<\) sample 2 \(<\) sample 7 \(<\) sample 5, and the order of the plastic viscosity \(\eta\) value of the mortar samples is sample 2 \(<\) sample 3 \(<\) sample 4 \(<\) sample 5 \(<\) sample 6 \(<\) sample 7. Under the same rotational speed, the corresponding shear stress-sequence in the initial state of the mortar is: 2# \(<\) 3# \(<\) 4# \(<\) 6# \(<\) 5# \(<\)7#, and the shear stress of the mortar gradually increases in this sequence. The collected data on the rheological properties (shear stress-shear rate variation) of the mortar samples after 1 h plus 40 min are presented Figure 11:  
Figure 10: The initial flow properties (shear stress-shear rate variation) of the samples. The shear yield stress \(\tau_{0}\) value of the mortar samples after 1 h plus 40 min follows the order sample 4 \(<\) sample 3 \(<\) sample 6 \(<\) sample 5 \(<\) sample 2 \(<\) sample 7, and the order of the plastic viscosity \(\eta\) value of the mortar samples is sample 2 \(<\) sample 3 \(<\) sample 4 \(<\) sample 5 \(<\) sample 6 \(<\) sample 7. Comparing Figures 8 and 9 reveals that the shear stress of sample 2, lacking any superplasticizer, poorly follows a linear correlation with shear rate, indicating that the cement mortar tends to flocculate. As the rheometer speed increases, the shear stress \(\tau\) rises sufficiently to suppress the interlocking of the cement particles and therefore destroy the agglomerated structure formed by flocculation; thus, the cement mortar obtains a certain degree of fluidity again. It is also clear that the amplitude of the variation in the shear yield stress \(\tau\) of samples 3 and 4 is smaller, and the plastic viscosity of the samples represented by the slope of the curves is also lower. The larger y-intercepts of the curves of samples 6 and 7 indicate that the shear yield stress \(\tau\) of the mortar samples is larger, and a larger slope of these curves also represents higher plastic viscosity \(\eta\). Additionally, the effect of early-strength functional polycarboxylic acid water-reducing agent, as a high-performance superplasticizer accelerating the cement hydration reactions, on the shear behavior of the cement mortar is more obviously reflected. The initial flow, shear yield stress (\(\tau_{0}\)), and plastic viscosity (\(\eta\)) of the mortar samples are also tabulated in Table 7.  
According to Table 7, the plastic viscosity \(\eta\) of the mortar samples mixed with the functional polycarboxylic acid superplasticizer is higher than that of the blank sample, while their fluidity, except for sample 4 containing superplasticizer H, is greater compared to the blank sample. Except for the naphthalene-based superplasticizer and early-strength functional polycarboxylic acid superplasticizer Z, the other mortar samples have smaller shear yield stress \(\tau\) and better fluidity compared to the blank group. Further, functional polycarboxylic acid superplasticizers can effectively improve the rheological properties of fresh mortar. Specifically, compared to sample 5, which contains \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Sample** & **Water-Reducing** & **Initial Flow** & **Initial \(\tau_{0}\) (Pa)** & **Initial \(\eta\)** & **\(\tau_{0}\) (Pa) after 1** & \(\eta\) (Pa-s) after 1** \\
**ID** & **Agent Type** & **(mm)** & **\(\tau_{0}\) (Pa)** & **(Pa-s)** & **h Plus 40 min** & **h Plus 40 min** \\ \hline
2 & None & 120 & 508.39 & 1.23 & 1000.00 & 3.54 \\
3 & J & 180 & 436.24 & 6.03 & 450.79 & 7.15 \\
4 & H & 110 & 378.20 & 8.72 & 309.78 & 9.71 \\
5 & NF & 155 & 596.03 & 15.57 & 755.57 & 14.88 \\
6 & Z & 200 & 334.24 & 16.85 & 630.98 & 16.58 \\
7 & Z & 150 & 576.94 & 18.04 & 1460.90 & 16.79 \\ \hline \hline \end{tabular}
\end{table}