硫酸盐/氯盐侵蚀耦合作用下水泥基材料离子扩散性能的评价与预测

The erosion failure of most of concrete structure subjected to coupling attacks of sulfate and chorine salts become serious increasingly nowadays, while the study associated the evaluation and prediction of ion diffusion property of cement-based materials under salts attacks is very limited. This proposal attempts to establish the theoretical relationship between electrical impedance response of cement-based materials and fractal property of pore structure. The innovative non-contact impedance measurement and advanced fractal simulation will be adopted to continuously obtain the fractal dimension parameters of pore structure in different kinds of cement-based materials. These fractal dimension parameters will be verified by some traditional fractal analysis techniques (mercury intrusion porosimetry, nitrogen adsorption technique and low temperature differential thermal method). Based on the fractal evolution of pore structure in cement-based materials, a simulation for the evolution of pore structure and the prediction of transportation properties (permeability and ion diffusion) will be developed. Besides, when coupling attacks of sulfate and chorine salts are taken into consideration，this proposal will further utilize 'salts solution+ material slice with any hydration age' method with the help of non-contact impedance measurement to analyze the influence of the salt concentration on coupling attacks. Eventually, when salt attacks are taken into account, the simulation and prediction above will be improved to provide theoretical support to the durability study of cement-based materials.

针对目前我国大量水泥基材料工程受硫酸盐和氯盐等盐类侵蚀日趋严重，而相关的水泥基材料在盐类侵蚀作用下的离子扩散性能的评价与预测研究却较为滞后的现状，本课题拟基于电阻抗响应与孔结构分形的理论关系，采用新型非接触阻抗仪方法，并结合先进的分形计算机模拟技术和传统常规的分形测量技术（压汞法、氮吸附技术和低温差热法）对不同水泥基材料体系的孔结构分形维数进行分析与验证，开展孔结构分形计算机模拟并建立水泥基材料在长服役条件下的传输性能（渗透特性和离子扩散特性）预测方法。本课题进而针对外部硫酸盐/氯盐侵蚀耦合作用下，采用“侵蚀溶液+任意龄期的水泥基材料切片”的非接触阻抗仪测试方法，逐一分析硫酸盐的浓度对氯盐侵蚀的影响和氯盐的浓度对硫酸盐侵蚀的影响，改进水泥基材料在硫酸盐/氯盐侵蚀耦合作用下离子扩散性能的预测方法，从而为水泥基材料耐久性的研究提供理论支撑。

我国正在实施的“丝绸之路经济带”和“21世纪海上丝绸之路”战略需要兴建大量的基础设施工程，如交通运输工程和海岸与近远海工程。这些工程材料服役于西部高盐或者侵蚀海水环境中。盐类侵蚀将严重缩短这些工程材料的服役寿命，进而导致巨大的经济损失，而相关的水泥基材料在盐类侵蚀作用下的离子扩散性能的评价与预测研究却较为滞后的现状。本项目主要围绕三个研究内容开展研究:1) 水泥基材料电阻抗响应与孔结构的分形特征关系; 2)非接触阻抗仪对孔结构分形维数的在线获取与验证; 3) 水泥基材料在硫酸盐/氯盐侵蚀耦合作用下离子扩散性能的评价。本项目通过提取水泥基材料的电阻抗数据，并结合分形孔结构网络模型和分形电阻抗响应网络模型，发现水泥浆体孔隙率、孔结构表面分形维数和体积分形维数之间并没有直接的联系。本项目采用“侵蚀溶液+任意龄期的水泥基材料切片”的非接触阻抗仪测试方法，逐一分析硫酸盐的浓度对氯盐侵蚀的影响和氯盐的浓度对硫酸盐侵蚀的影响。基于实验侵蚀数据，本项目建立了水泥基材料的孔结构演变的分形计算机模拟并提出了水泥基材料在硫酸盐/氯盐侵蚀耦合作用下的离子扩散性能预测方法。