## 5 Conclusions  
This study investigates the impact of biopolymers (XG, LBG, and GG) on the mechanical properties of GRS. The analysis focuses on variations in UCS and shear strength under different biopolymer concentrations (0%, 0.5%, 1.0%, 1.5%, and 2.0%) and curing times (0, 3, 7, and 14 days). UCS and direct shear tests were conducted on samples with varying biopolymer contents and curing times to evaluate the macro-mechanical properties of the soil. Additionally, SEM and XRD techniques were employed to explore the effects of biopolymers on the microstructure of GRS and the mechanisms involved. The main conclusions are as follows:  
1. Biopolymers significantly improved the strength of GRS, enhancing both its E-value and _TI_ value. The beneficial effect of biopolymers became more pronounced as the curing time increased.
2. Each biopolymer exhibited an optimal content for improving GRS strength, with variations between biopolymers. The optimal concentrations for XG and LBG were 1.5%, while for GG, it was 2.0%.
3. Among all the biopolymers, GG had the most significant impact on improving the strength of GRS. With the addition of 2.0% GG, the UCS and shear strength of the treated soil increased by 1.6 and 1.58 times, respectively, compared to untreated GRS.
4. The content of biopolymers influenced the macroscopic failure behavior of the soil. As biopolymer content increased, the failure shear band in the UCS test became more distinct.
5. Biopolymers had a more significant effect on improving the cohesion of GRS than the internal friction angle. After treatment with XG, LBG, and GG, the soil cohesion increased by 1.36, 1.34, and 1.55 times, respectively, compared to untreated soil.  
However, the maximum curing time in this study was 14 days. Future research could consider extending the curing period to explore the changes in the mechanical properties of granite residual soil over a longer timescale with biopolymers. Additionally, the opti  
Figure 22: Curing differences between GRS and biopolymer-treated soil: (**a**) GRS; (**b**) biopolymer-treated soil.  
mal concentration of guar gum was not determined in this study. The research primarily focused on the effect of a single biopolymer, and only three types of biopolymers were selected. Future work could further explore the synergistic effects of multiple biopolymers and identify the optimal mixing ratio to enhance the mechanical properties of the soil. In practical engineering, granite residual soil may be influenced by a combination of environmental factors, such as temperature, rainfall, and wet-dry cycles. Future experiments could investigate the performance of biopolymer-modified soil under complex environmental conditions and analyze its long-term stability and durability.  
Writing--original draft, L.Y.; writing--review and editing, Y.L.; project administration, J.W. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the National Natural Science Foundation of China (52078195, U22A20232).  
Not applicable.  
The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author(s).  
The authors declare no conflicts of interest.