## 5 Conclusions  
This study investigated the mechanical responses of asphalt pavements under traffic loads using fiber Bragg grating (FBG) sensing technology and evaluated the performance of various grouting materials, yielding the following conclusions:  
1. By deploying FBG sensors at the top of the pavement base layer, this study collected real-time mechanical response data under extensive vehicular loading. Through comparative analysis of mechanical response characteristics across sections and using the back-calculated pavement elastic modulus as an evaluation metric, an assessment methodology for grouting treatment effectiveness on cracks in semi-rigid base asphalt pavements was proposed. The findings provide guidance for the design of grouting materials, optimization of injection processes, and post-treatment maintenance strategies for semi-rigid base asphalt pavements.
2. High-strength geopolymer grouting materials significantly improved pavement mechanical performance. The average elastic modulus of asphalt increased by 34% for high-strength geopolymer without waterproofing agents and 19% for the variant with waterproofing agents. Polymer grouting achieved an average elastic modulus of 676.15 MPa, demonstrating notable enhancement. In contrast, low-strength geopolymers showed limited efficacy, with minimal changes in pavement modulus. These findings confirm the superior performance of high-strength geopolymers and polymers, making them suitable for high-load road structures. The ranking of average elastic modulus values across treated sections is as follows: high-strength geopolymer (without waterproofing agents) > polymer > high-strength geopolymer (with waterproofing agents) > low-strength geopolymer (without waterproofing agents) > low-strength geopolymer (with waterproofing agents) > intact pavement > untreated pavement.  
This study evaluated the short-term effectiveness of grouting treatments. Subsequent research should investigate the long-term performance of grouting materials under diverse environmental conditions (e.g., varying temperatures, moisture levels). The accuracy of this methodology can be further validated by integrating FWD field data and numerical simulation results. Furthermore, more refined sensor deployment configurations and optimized modulus back-calculation algorithms should be implemented to enhance the accuracy and applicability of research outcomes.  
Conceptualization, M.Z. and H.H.; data curation, Z.S.; formal analysis, X.M.; funding acquisition, M.Z. and H.H.; investigation, M.Z.; methodology, X.M.; project administration, M.Z. and H.H.; resources, H.H.; supervision, X.M.; validation, C.R., Z.S. and X.M.; visualization, Z.S.; writing--original draft, C.R.; writing--review and editing, C.R. and X.M. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China (Grant No. 52478451) and technology project of Guangzhou Suihua Intelligent Traffic Technology Co., Ltd.  
Not applicable.  
Data Availability Statement: The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.  
The authors declare that this study received funding from Guangzhou Suihua Intelligent Traffic Technology Co., Ltd. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication. And authors [PERSON] and [PERSON] were employed by the company Guangzhou Suihua Intelligent Traffic Technology Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.