复杂环境作用下水泥乳化沥青砂浆的水分迁移机制及结构演变微观机理研究

The cement asphalt mortar is an important material of ballastless slab track for high-speed railway. The poor durability due to the effect of complex environments and loads is the main problem for cement asphalt mortar in our country, which restricts the velocity of high-speed railway, and even may bring huge safety trouble. .The object of this research is determine the design standard of mix proportion and raw materials’ criterion of cement asphalt mortar under the complex conditions. The research conclusions will be helpful for improving the whole technique level of high-speed railway..First, the water evaporation and hydration process and water residue in the fresh mortar with different mix proportions will be analyzed by Nuclear Magnetic Resonance (NMR). The micro structure of cement asphalt mortar after curing 28d will be studied by NMR and Atomic Force Microscope (AFM). The changing law of water content, water distribution, water status and the micro structure characteristic with different mix proportions will be concluded according to the test results..Second, the fatigue test under the coupling conditions of water, temperature and load will be designed according to the actual status which the ballastless slab track of high-speed railway is suffering. The water intrusion and movement process in hardened cement asphalt mortar will be analyzed by NMR. As the same time, the micro-structure evolution of hardened cement asphalt mortar will be studied by NMR and AFM. The law and the key influence factors of water migration and the micro-structure evolution will be concluded for hardened cement asphalt mortar with different mix proportions. .Third, the evaluation method of water stability performance will be proposed according to the research above. The quantitative relationship between water stability performance and micro structure will be put forward. The design standard of mix proportion and raw materials’ criterion of cement asphalt mortar under the complex conditions will be presented finally.

水泥乳化沥青砂浆是高速铁路无砟轨道的关键工程材料，然而目前水泥乳化沥青砂浆普遍存在抗水损性能差、长期耐久性不足的现象，严重影响高铁运行质量与速度。本项目针对此现状，就其基础性问题——复杂环境作用下水泥乳化沥青砂浆水分迁移机制及结构演变微观机理展开研究。通过模拟我国高铁运营环境，开展在水、温度和荷载复杂环境作用下材料的疲劳性能试验，利用低场核磁共振仪和原子力显微镜监测水泥乳化沥青砂浆的水分迁移过程和微观形态特征，掌握水泥乳化沥青砂浆中水分变化和结构形态特征的演变规律；揭示复杂条件下水泥乳化沥青砂浆的水分迁移机制及结构演变的微观机理；建立宏观抗水损性能与微观形态特征的关系方程，以便定量反映原材料性质、配合比等对水泥乳化沥青砂浆抗水损性的影响。基于性能平衡设计，提出适于复杂环境长期耐久的水泥乳化沥青砂浆的配合比设计原则及原材料选择判据，为从性能出发进行水泥乳化沥青砂浆的设计奠定基础，为高铁技术的整体提升提供技术储备。

本课题针对高铁关键工程材料——水泥乳化沥青砂浆长期耐久性不足问题，就其基础性问题——复杂环境作用下水泥乳化沥青砂浆水分迁移机制及结构演变微观机理展开了研究。首先，利用低场核磁共振技术，对新拌水泥乳化沥青砂浆水化过程中的自由水进行实时监测，揭示了新拌水泥乳化沥青砂浆中自由水分的迁移规律；其次，利用低场核磁共振技术、电子扫描电镜、CT扫描等技术手段，对硬化后的水泥乳化沥青砂浆的微观形态与形貌特征进行观测，掌握了原材料及配合比对水泥乳化沥青砂浆硬化后的微观形态特征的影响规律及关键影响因素；再次，结合实际使用情况，设计了水分渗析试验，揭示了复杂条件下水分在水泥乳化沥青砂浆中的迁移机制，最后，通过模拟我国高铁运营环境，对水、温度和荷载多因素耦合作用下的强度和疲劳特性等宏观性能进行了测定，建立了宏观性能与微观特征的定量关系，可定量反映原材料性质及配合比对水泥乳化沥青砂浆宏观性能的影响。提出了适于复杂环境长期耐久的水泥乳化沥青砂浆的配合比设计原则及原材料选择判据，为从性能出发进行水泥乳化沥青砂浆的配合比设计奠定了基础，为高铁技术的整体提升提供了技术储备。