## 2 Study Methods and Process
### Materials Used for SBR Late Mortar
#### 2.3. Mortar Mixture  
The mortar mixture was prepared according to the material-inputting order shown in Figure 2, following the mixture ratio of the test plan. The preparation process involved the following steps. This process ensured a consistent and homogeneous mortar mixture for the subsequent tests.  
1. The sand and cement were added to the mixing container in the specified order.
2. The materials were mixed with a hand mixer at low speed for 30 s to ensure an even distribution of the dry components
3. Water was then poured into the mixture and mixed for an additional 30 s at low speed.
4. SBR latex was added to the mixture according to the specified input ratio.
5. The mixture was then mixed at high speed for 60 s to ensure thorough blending of all components.
6. The final mortar mixture was then ready for use in the tests.  
Specimens were prepared with varying SBR latex incorporation rates and were examined using a scanning electron microscope (SEM) to observe the composition and manifestation process within the cement matrix. The specimens were photographed at 14 days of age, a point at which significant strength development is evident. Figure 3 shows the internal images of the specimens taken at 5000\(\times\) magnification using an SEM for different SBR latex incorporation rates.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{2}{*}{**Appearance**} & **Glass** & \multirow{2}{*}{**Solid Content** (\%, tsc)**} & **Specific Gravity** & **Particle Size** (\(\mu\)m) & **pH** (25 °C) & **Viscosity (25 °C, cP)** & **Surface Tension (dyne/cm)** \\ \cline{2-7} Milky white suspension & \(+4\,^{\circ}\)C & \multirow{2}{*}{47.5} & \multirow{2}{*}{1.010} & \multirow{2}{*}{0.20} & \multirow{2}{*}{10.3} & \multirow{2}{*}{70} & \multirow{2}{*}{35} \\ \cline{2-7}  & \(-16\,^{\circ}\)C & & & & & \\ \hline \end{tabular}
\end{table}
Table 2: Physical properties of SBR latex.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{2}{*}{**Styrene**} & **Butadiene** & \multirow{2}{*}{**Nonionic** **Surfactant**} & **Anionic** & \multirow{2}{*}{**Potassium**} & \multirow{2}{*}{**Persulfate**} \\  & & & & & & \\ \hline
58.3\% & 35\% & 6\% & 0.2\% & 0.3\% & 0.2\% \\ \hline \end{tabular}
\end{table}
Table 3: Chemical composition of SBR latex.  
Figure 2: Mortar-mixing method and order.  
These SEM images provide a detailed look at how different incorporation rates of SBR latex influence the internal structure and properties of the modified mortar. The increased porosity and the formation of a polymer network within the cement matrix contribute to the material's ability to mitigate noise and vibration.  
As shown in Figure 3, it was observed that the number of pores increases with the incorporation rate of SBR latex. Additionally, Figure 4 shows a specimen with a 7% SBR latex incorporation rate at 5000\(\times\) magnification, illustrating the mechanism by which SBR latex bonds with cement. These pores act as air layers within the cement, and the latex binding within the cement gaps manifests the rubber properties of the latex. This interaction suggests that the latex-modified mortar can help reduce noise and vibration from floor impacts.  
Figure 4: Scanning electron microscope (SEM) images of SBR latex-modified mortar at SBR latex incorporation rate of 7%.  
Figure 3: SEM images of specimens with varying SBR latex incorporation rates (5000\(\times\) magnification). (**a**) 0% SBR latex: general mortar. (**b**) 5% SBR latex incorporation rate. (**c**) 7% SBR latex incorporation rate. (**d**) 9% SBR latex incorporation rate.