PTB乳液改性砂浆性能及其机理分析

为解决运营隧道结构修复材料面临受力变形、渗流侵蚀等因素而再次破坏的难题,采用PTB乳液对砂浆进行改性提供性能优异的修复材料。通过宏观性能和微观结构相结合的方法,研究了PTB乳液对改性砂浆力学性能、柔韧性、粘结性能和抗渗性能的影响,并从孔隙结构和微观形貌对改性机理进行分析。结果表明：PTB乳液使得砂浆抗压强度下降,但提高了其抗折强度,压折比降低,压缩韧性指数提高;随PTB乳液掺量的增加,拉伸粘结强度和剪切粘结强度均增加;改性砂浆抗渗强度增加,吸水率降低,具有良好的防水性能;PTB乳液掺入后降低了砂浆的总孔隙率,聚合物网膜连接水化产物和未水化水泥颗粒,形成填充密实的网状结构,改变了砂浆的强度、同时也是其韧性、粘结性能、抗渗性得以提高的主要原因。可见PTB乳液对材料韧性能、粘结性能、抗渗性能具有改善作用,满足作为运营隧道病害修复材料使用,研究结果旨在为聚合物改性砂浆的优化设计和实际应用提供参考。

Property of PTB emulsion modified mortar and the analysis of modification mechanism

In order to solve the problem that the repair materials of operation tunnel structure are damaged again due to stress deformation, seepage erosion and other factors, PTB emulsion was used to modify the mortar in this study. The effects of PTB emulsion on the mechanical properties, pliability, bond strength and impermeability were studied. Meanwhile, the modification mechanism was analyzed from the microstructure and pore morphology. The results show that the incorporation of PTB emulsion reduces the compressive strength of mortar and significantly improves the flexural strength. The compressive to flexural ratio of modified mortar decreases, the compression toughness index increases, so the pliability increases. With the increase of PTB emulsion content, the tensile bond strength and shear bond strength increase. The Anti-Permeability strength of modified mortar increases, water absorption rate decreases. Thus, the modified mortar has good waterproof performance. The incorporation of PTB emulsion reduces the total porosity, and the polymer membrane connects the hydration products and cement particles to form a dense spatial skeleton-matrix network structure. These change the strength of the mortar and are also the main reason for the improvement of Pliability, bond strength and impermeability. This study aims to provide reference for the optimization design and practical application of polymer modified mortar.