高耦合水泥基压电复合监测材料及应用基础研究

Concrete is the most widely used materials in civil engineering field, however, there is still no effective monitoring materials and technology suitable for long-term monitoring of concrete engineering. This project mainly focuses on the key fabrication technique, properties control and application foundation research of the cement based piezoelectric composite monitoring materials on basis of the coupling mechanism between the composite monitoring material and concrete. The constitution of interface of the composite monitoring material will be designed to improved the coupling properties of the composite monitoring material, and the optimum modifying technique and structure of the interface will also be determined. The assembling pattern of the structural unit and distribution symmetry in space of the composite monitoring material will be improved to design and fabricate the novel cement based composite monitoring materials owing the location ability. The damage location mechanism will also be studied. The packaging materials of high strength, high insulativity and good corrosion resistance ability will be studied to improve the monitoring accuracy and stability as well the electrode fabrication technique suitable for cement based piezoelectric composite. The long term durability and reliability of the cement based piezoelectric composite monitoring sensor will be studied based on the mechanical-electrical-acoustic property investigation of cement based piezoelectric composite sensor under the coupling loading of multiple-field. Finally, the online monitoring system will be built based on the research of optimum layout of the sensors and relativity research between monitoring signal and concrete damage.

混凝土是土木工程领域用量最大的材料，因耦合问题，目前尚未有一种有效的智能材料能够实现对混凝土结构的长期有效监测。本项目通过材料组成设计、构造创新及模型构建，研发高耦合水泥基压电复合监测材料，探究其与混凝土的耦合作用机制，并进行制备技术、性能调控及工程应用基础研究。设计水泥基压电复合监测材料的界面改性组成体系，明确最佳的改性工艺及界面组成与结构，增强监测材料的耦合性能；通过改进结构单元的复合组装形式和空间分布对称性，设计并制备具有定位功能的水泥基压电复合监测材料，揭示其损伤定位机理；设计并制备高强、高绝缘、耐腐蚀的封装材料，找到适用于水泥基压电复合监测材料的电极制备技术，提高监测精度和稳定性；探明水泥基压电复合监测传感器在多场耦合载荷作用下的力-声-电性能变化规律，研究其耐久性和可靠性，最终通过传感器优化布设及监测信号和混凝土的损伤相关性研究，构建在线监测系统。

本项目针对混凝土结构安全监测需求，开展高耦合水泥基压电复合监测材料与器件的关键制备技术和应用基础研究。为提高压电陶瓷与基体的结合性，利用强酸对压电陶瓷进行表面粗化，确定了最佳的压电陶瓷粗化工艺参数为HNO3/HF=0.5、粗糙度1.5μm。为提高压电陶瓷与基体的界面耦合性，利用溶胶-凝胶法在压电陶瓷表面生长与水泥组成相似的硅、钙、钛系列薄膜，研究了反应温度、陈化温度、陈化时间和pH值等参数对其性能的影响，明确了各种类型薄膜的最佳制备工艺。采用切割-浇注与排列-浇注结合的方法制备了正交异性压电复合材料，研究了形状参数、并联个数、基体配合比等对其压电、机电及正交异性等性能的影响，在此基础上制备了正交异性压电传感器，对其平面信号响应及衰减性能研究表明，正交异性压电传感器具有较高的灵敏度和带宽，信号幅值曲线与信号电压曲线具有“余弦”变化趋势，正交异性特性明显。设计并制备了系列压电超声及声发射换能器，开展了钢筋机械损伤、锈蚀损伤及混凝土冻融损伤监测研究，钢筋锈蚀损伤超声监测结果表明，随着锈蚀时间的增加，超声表面波幅值逐渐减小，当锈蚀达到一定程度后出现明显的超声反射回波；基于声发射技术的混凝土冻融损伤监测结果表明，混凝土冻融损伤可分为四个阶段：即微裂纹萌芽期、微裂纹发展壮大期、微裂纹衰减期和微裂纹稳定期，通过最小二乘法建立了混凝土冻融损伤阶段内部裂纹发展的声发射评判方法，声发射源定位研究发现随着混凝土冻融次数的增加，冻融损伤声发射事件的出现频度减小。本项目探明了水泥压电复合材料与混凝土的力电声耦合作用规律、物理化学行为及智能感应特点，为土木工程结构健康监测奠定了材料、器件及工程应用理论基础，形成了具有我国自主知识产权的高耦合水泥基压电复合材料制备及工程应用技术体系，项目研究成果已成功应用于济南穿黄隧道、德国A4高速公路等健康监测工程，为重大土木工程结构安全服役提供了有力保障。

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