基于形状记忆效应的水泥路面嵌缝料自修复机理研究

The study on self-repairing mechanism is important to repair timely and effectively the various cracks or damage of embedded sewing material on the cement concrete pavement. In this study, the shape memory polymeric composite is selected as embedded sewing material. The simple 2D pre-deformation method is proposed to make the embedded sewing material possess shape memory function in horizontal and vertical direction, and store strain energy, and enhance the self-repairing function. It can perceive and response to environmental changes, and realizes the self-deformation to adapt the juncture width change. Also the anisotropy of embedded sewing material and its effects are analyzed. Changes of environment temperature cycle are as sealing material shape recovery incentives. Based on the diffraction intensity theory and thermodynamic entropy increase principle, the relationship of micro structure, internal stress, conformation entropy change in the embedded sewing material and shape memory effect will be understand. And thermodynamics constitutive model is establishedUnder the complex stress to describe the dynamic process of shape memory thermodynamics action, revealing shape memory effects of the embedded sewing material in the 2D directions. From the angle of bionics, the repairing process of injured organisms is simulated, putting forward the new idea of two-step self-repairing idea, namely first closed structure scale damage, then realize the molecular scale repairing. And this process has good repeatability. In addition, self-repairing mechanism based on shape memory effects and molecular migration and diffusion mechanism will be studied. This research can provide new idea to material self-repairing and improve the durability embedded sewing material on the cement concrete pavement.

研究水泥路面嵌缝料自修复机理对及时有效修复嵌缝料上的各种裂缝或损伤有重要意义。本项目以适宜推广的形状记忆复合材料作为嵌缝料，采用双轴预形变方法，分别沿水平和竖直方向同时进行预压和预拉形变，存储应变能，在二维方向上赋予嵌缝料形状记忆效应，增强自修复功能，能感知并响应环境变化，主动适应接缝宽度循环伸缩，分析嵌缝料各向异性及其对各项性能的影响；根据衍射强度理论和热力学熵增原理，以环境温度场循环变化作为嵌缝料形状恢复的激励手段，研究嵌缝料分子取向度、内应力、构象熵等变化与二维形状记忆效应的关系，建立复杂应力下热力学本构模型，揭示嵌缝料在二维方向上形状记忆效应原理；模拟生物体损伤后自愈合过程，提出两步骤自修复新理念，即先在形状记忆效应驱使下闭合结构尺度上裂缝或损伤两自由面，再通过两自由面间分子迁移扩散机制，实现分子尺度上自修复，且具有良好重复性。本研究为材料自修复研究、提高嵌缝料耐久性提供了新思路。

水泥路面是我国高等级路面的主要铺装类型之一，广泛用于公路、城市道路和机场跑道，且以接缝式水泥路面为主，接缝是水泥路面最薄弱的环节之一，嵌缝料耐久性是延长水泥路面使用寿命、提高服务品质的重要保证。嵌缝料在使用过程出现的各种裂缝或损伤如果不能得到及时有效修复，会严重影响嵌缝料的耐久性，导致水泥路面产生各种破坏。. 针对水泥路面嵌缝料在形状记忆功能预形变方法、形状记忆效应原理和嵌缝料自修复机理等方面存在的科学问题，本项目以适宜推广的多孔纳米二氧化硅颗粒增强形状记忆聚氨酯复合材料作为嵌缝料，提出双轴预形变方法，分别沿水平和竖直方向同时进行预压和预拉形变，存储应变能，在水平和竖直二维方向上赋予嵌缝料形状记忆效应，增强嵌缝料自修复功能，能感知并响应水泥路面接缝处环境温度变化，主动适应接缝宽度循环伸缩，研究了双轴预形变导致的嵌缝料各向异性特征及其对热稳定性、相转变温度、相结构变化、微观组织结构、力学性能等影响。. 根据衍射强度理论和热力学熵增原理，以环境温度场循环变化作为嵌缝料形状回复的激励手段，研究嵌缝料分子取向度、内应力、构象熵等变化与二维形状记忆效应的关系，揭示嵌缝料在水平和竖直二维方向上形状记忆效应原理；模拟生物体损伤后自愈合过程，提出了嵌缝料两步骤自修复新理念，即先在高温季节嵌缝料形状记忆效应回复力驱使下闭合结构尺度上宏观裂缝或损伤两自由面，再通过熔融嵌缝料基体内热塑性颗粒促使裂缝或损伤两自由面之间分子迁移和扩散，实现分子尺度上自修复，且该两步骤自修复方法具有良好重复性。. 本项目研究成果使已开裂或损伤的嵌缝料及时有效地得到自修复，提高嵌缝料的耐久性，延长水泥路面使用寿命，改善路面使用品质，促进了水泥路面又好又快发展，发挥了水泥路面在国家路网结构中的重要作用。