## 3 Results and Discussion
### Mortar Analysis  
#### 3.2.1 Mortar Fluidity  
Generally, to evaluate the workability of fresh mortar, its rheological properties are analyzed under different conditions. A common method to test the rheological properties is to measure the fluidity of freshly mixed mortar. To this end, the initial fluidity of the mortar and the fluidity of the mortar after 1 h plus 40 min are measured, as depicted in Figure 9.  
As tabulated in Table 6, under the same water consumption conditions, sample 1 of the blank group shows no initial fluidity and slightly bleeds after 1 h plus 40 min. Sample 2 of the blank group (light bleeding) is prepared by increasing the water consumption from 400 to 600 g; it is clear that increasing water consumption leads to poor workability, therefore increasing the water-to-cement ratio is not recommended. Samples 1 and 2 were selected as the control group. The comparison between samples 2 and 3 reveals that the initial fluidity of sample 3 (180 mm) is much larger than that of sample 2 (120 mm, light bleeding). The fluidity of sample 3 after 1 h plus 40 min (170 mm) still remains good, and its fluidity loss over time is small (5.9%), which confirms that water-reducing polycarbonate acid superplasticizer J has better water-reducing and slump retention properties. Sample 4 contains a sustained-release polycarboxylic acid high-performance water-reducing agent. The initial fluidity of sample 4 (110 mm) is slightly less than that of sample 2 (120 mm), and its fluidity increases with time (165 mm after 1 h plus 40 min), indicating that the water-reducing effect of the superplasticizer H is gradually produced after 1 h plus 40 min, that the fluidity still improves, and that there is no loss of fluidity over time. Figure 8: Effects of different superplasticizers on the cumulative pore volume of the cement paste. Figure 9: Fluidity of the mortar: diagonal stripes denote initial mortar fluidity and dots denote mortar fluidity after 1 h plus 40 min. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample ID**} & **Water-Reducing** & **Initial Mort** & **Morat Fiulity** & **Loss of** & **Loss of** & **Mortar** & **Mortar** \\  & **Agent Type** & **Initial Mort** & **after 1 h Plus 40** & **Fidelity over** & **Fliudity over** & **Compressive** & **Compressive** \\  & **Agent Type** & **Fliudity (mm)** & **min (mm)** & **Time (mm)** & **Time (\%)** & **Strength after 1** & **Strength after 7** \\  & & & & & & **Day (MPa)** & **Days (MPa)** \\ \hline
1 & None & No fluidity & Bleeding & - & - & - & - \\
2 & None & 120 & 85 & 35 & 41.2 & 20.8 & 33.0 \\
3 & J & 180 & 170 & 10 & 5.9 & 36.1 & 53.0 \\
4 & H & 110 & 165 & \(-\)55 & \(-\)33.3 & 26.2 & 39.4 \\
5 & NF & 155 & 100 & 55 & 55.0 & 38.3 & 61.2 \\
6 & Z & 200 & 155 & 45 & 29.0 & 46.4 & 67.3 \\
7 & Z & 150 & 105 & 45 & 42.9 & 46.3 & 66.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: The fluidity and compressive strength of cement mortar. Although the initial fluidity of sample 5 (155 mm) is higher than that of the blank sample 2, its initial fluidity is less compared to sample 3 (180 mm), and its rate of fluidity loss over time (55 mm) is much greater than that of sample 3 (10 mm), which reflects the influence of polycarboxylic acid high-performance water-reducing agent. Thus, superplasticizer J is better than naphthalene-based water-reducing agent and has better adaptability to cement. The initial fluidity of samples 6 and 7 (which are based on superplasticizer Z) is much higher than that of the blank sample, i.e., sample 2, indicating that increasing the amount of early-strength polycarboxylic acid high-performance water-reducing agent improves the fluidity of cement mortar; however, it seems that the change of the dosage of superplasticizer has no obvious impact on the compressive strength of the cement mortar after 1 day (compare sample 6 with sample 7).