高吸水性聚合物改性水泥-膨润土竖向防污屏障的抗裂与自愈合机理研究

水泥-膨润土竖向防污屏障在污染场地防治工程被广泛使用，但屏障材料面临着在复杂服役环境下易开裂失效且难以修复的问题，增加了场地污染物的扩散风险。本项目首创性地提出利用高吸水性聚合物来改良水泥-膨润土的抗裂与自愈合性能。通过宏观力学、化学和渗透试验及微观结构分析方法，明确高吸水性聚合物对于水泥-膨润土材料的物理、力学及化学性能的影响规律和机理；通过模拟复杂环境条件的模型试验，基于改性水泥-膨润土强度和渗透系数动态变化、裂缝发育过程和微观表征分析，明确其抗裂性能的提升效果和影响机理；通过多种破坏模式下改性水泥-膨润土的裂缝愈合效果、强度和渗透系数恢复程度并结合微观表征和微型CT扫描技术，揭示高吸水性聚合物对水泥-膨润土自愈合性能的提升效果和影响机理；最终构建具有抗裂-自愈合双重防护功能的水泥-膨润土长效竖向防污屏障体系。研究成果将为水泥-膨润土防污屏障的设计优化提供重要的理论和技术支持。

Cement-bentonite cut-off walls are commonly used in contaminated land remediation applications. However, the cut-off wall materials deteriorate and crack in complex environments, and such cracking is difficult to repair, increasing the possibility of the dispersion and diffusion of contaminants. This project aims at improving the crack-resistant and self-healing performance of cement-bentonite by incorporating superabsorbent polymers. A series of comprehensive laboratory tests and microstructural analyses will be carried out to optimize the proportions of each component of cement-bentonite, and to investigate the effects of superabsorbent polymers on the physical, mechanical and microstructural properties of cement-bentonite subjected to wet-dry and freeze-thaw cycles and chemical attack. The inhibition of crack development due to the superabsorbent polymers will be studied, and the crack-resistance performance and mechanism of the modified cement-bentonite will be investigated. Furthermore, progressive damage tests, performance recovery tests, micro-CT tests and microstructural analyses will be conducted to study the effects of superabsorbent polymers on crack sealing and the formation of self-healing products and to investigate the self-healing performance and mechanism. This project will develop crack-resistant and self-healing cement-bentonite cut-off wall systems for long-term service, and provide important theoretical and technical support for cement-bentonite cut-off wall design and applications.