## 5 Conclusions  
Through the performance analysis, it has been found that the ecological protection of the polymer curing agent has many advantages, which provides a reference for similar projects. However, slopes with different geological conditions have different ecological protection methods. Therefore, when the ecological protection method in this study is applied in similar slope protection projects, local geological conditions should be taken into consideration.  
(1) The stability safety factor of the weak slope under the protection of the polymer curing agent was analyzed by the strength reduction method. It was found that after the weak rock slope was treated by the polymer curing agent in this project, the safety factor of the slope stability increased.  
(2) On the basis of laboratory and on-site experiments, the effects of the polymer curing agent on the weak rock slope were studied. From the laboratory test results, it can be seen that the strength, water stability, and surface microstructure of the weak rock slope were improved by the polymer curing agent layer. A curing layer with certain hydration resistance and softening resistance on the  
Figure 16: Plant growth condition of the Hunan test slope: (**a**) 1 month later; (**b**) 3 months later; (**c**–**d**) 6 months later.  
surface of excavated weak rock slope can be formed. From the on-site test results, it is shown that the weak slope surface has high hydration resistance and softening resistance. It can meet the requirements of the curing treatment of the weak rock slope.  
(3) From laboratory tests, it is observed that the change of properties of the curing agent depends on the polymer-cement ratio and curing time. The bonding strength increases as the curing time increases. From SEM images, it is indicated that the polymer curing agent has an interaction between the polymer emulsion, cement, and soft rock. These interactions have greatly changed the surface structure and physical and chemical properties of soft rock, thereby improving the strength, water stability, and erosion resistance of the slope surface.  
(4) From on-site tests, it is indicated that the polymer curing agent of the weak slope is beneficial to improve the water-damage resistance of the slope surface and prevent or reduce the softening of weak rock, thus allowing the greening of the weak rock slope. Through this research, it is clearly pointed out that the styrene-acrylic emulsion cement-matrix composite material could be used as a new type of polymer curing agent for weak slope ecological protection engineering. This technique is worth applying in weak slope ecological protection.  
Data curation, D.Y. and J.L.; investigation, D.Y. and J.Y.; methodology, D.Y., J.L. and J.Y.; writing--original draft, D.Y. and J.L.; writing--review and editing, G.Q. and J.Y.  
This study was supported by the National Natural Science Foundation of China (51778071), Transportation Science and Technology Project of Zhejiang Province, China (grant number 2015)17) and Transportation Science and Technology Project of Hunan Province, China (grant number 201505).  
We express our sincere gratitude to [PERSON] of Department of Economic Management, Changsha University of Technology, and anonymous reviewers for their constructive comments.  
We declare no conflict of interest.