## 2 Performance Test of Waterproof Cohesive Layer Material
### Testing Procedure and Result  
#### 2.3.1 SBS-Modified Emulsified Asphalt  
SBS-modified emulsified asphalt was sprayed with areal densities of 0.8, 1.0, 1.2, 1.4, and 1.6 kg/m\({}^{2}\), and gravel was sprayed with areal densities of 5.0, 6.0, 7.0, and 8.0 kg/m\({}^{2}\), yielding a total of 20 waterproof materials. According to the test scheme Emu-A-brushed, Emu-A-grooved, Emu-B-brushed, Emu-B-grooved, and Emu-B-exposed, each type of adhesive material specimen was prepared and tested using a direct shear test (please refer to Table 1 for details). The experimental results are shown in Figure 2, and the amount of asphalt and gravel content corresponding to the maximum shear strength is taken as optimum.  
Figure 2 shows that the optimum asphalt content in scheme Emu-A-brushed, Emu-A-grooved, Emu-B-brushed, and Emu-B-grooved is 1.2 kg/m\({}^{2}\), and the optimum gravel content is 6.0 kg/m\({}^{2}\). The optimum asphalt content of scheme Emu-A-exposed and Emu-B-exposed is 1.4 kg/m\({}^{2}\), and the optimum stone content is 7.0 kg/m\({}^{2}\). The shear strength of the waterproof cohesive layer initially increases, and then decreases as the gravel content increases. This is because increasing the amount of gravel will increase interlaminar compression when the amount of asphalt is fixed. When the amount of aggregate reaches a critical point, a continuous increase in aggregate will cause bonding damage, which will decrease the interlaminar shear strength.  
After determining the optimum amount of asphalt and gravel content in scheme A, the upper asphalt was sprayed with areal density of 0.2, 0.4, 0.6, 0.8, or 1.0 kg/m\({}^{2}\), which is composed of five kinds of waterproof adhesives material. According to the test scheme Emu-C-brushed, Emu-C-grooved, and Emu-C-exposed, each kind of waterproof adhesive material was prepared and direct shear tests were carried out (please refer to Table 1 for details). The test results are shown in Figure 3, and the amount of sprayed asphalt content corresponding to maximum shear strength is taken as optimum.  
Figure 3 shows that the optimum asphalt content in the upper modified asphalt in scheme Emu-C-brushed, Emu-C-grooved, and Emu-C-exposed is 0.6 kg/m\({}^{2}\). The best asphalt content in scheme Emu-C-brushed and scheme Emu-C-grooved is 0.6 kg/m\({}^{2}\) for the upper layer and 1.2 kg/m\({}^{2}\) for the lower layer, with 6.0 kg/m\({}^{2}\) for gravel content. The best asphalt content in scheme Emu-C-exposed is 0.6 kg/m\({}^{2}\) for the upper layer and 1.4 kg/m\({}^{2}\) for the lower layer, with 7.0 kg/m\({}^{2}\) for gravel content.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Type of the** & \multicolumn{8}{c}{**Passing Percentage (\%)**} & \multicolumn{8}{c}{**Optimum**} \\
**Mixture** & **19.0** & **16.0** & **13.2** & **9.5** & **4.75** & **2.36** & **1.18** & **0.6** & **0.3** & **0.15** & **0.075** & **Asphalt Content** \\ \hline AC-13 & 100 & 100 & 92 & 70 & 40.3 & 31.5 & 25.4 & 19.2 & 12.7 & 9.2 & 5.9 & 4.9\% \\ \hline \hline \end{tabular}
\end{table}
Table 6: Aggregate gradation.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Ingredient** & **Cement** & **Expansive** & **Sand** & **Fine** & **Coarse** & **Water** & **Admixture** & **Steel** \\  & & **Agent** & **Aggregate** & **Aggregate** & **Water** & **Admixture** & **Fiber** \\ \hline Proportion (kg/m\({}^{3}\)) & 440 & 38 & 761 & 404 & 605 & 172 & 5.736 & 50 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Mix proportion of cement concrete.  
Figure 3: Shear strength of SBS-modified emulsified asphalt under different upper layer asphalt content.  
Figure 2: Shear strength of SBS-modified emulsified asphalt with different spreading and disposal schemes: (**a**) Emu-A-brushed; (**b**) Emu-A-grooved; (**c**) Emu-A-exposed; (**d**) Emu-B-brushed; (**e**) Emu-B-grooved; (**f**) Emu-B-exposed.