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针对混凝土裂缝损伤演化及其检测,提出了一种基于交流阻抗谱法,根据材料阻抗特性参数进行裂缝检测或损伤评估的思路。采用钢筋作为电极,以混凝土的阻抗幅模量(z值)和相角值(φ值)作为材料阻抗特性参数,利用MT4090 LCR测量仪测量混凝土试件在劈裂抗拉过程中阻抗特性参数变化规律。根据测量结果分析混凝土损伤演化发展过程与阻抗特性参数之间的变化规律。试验结果表明:在混凝土劈拉破坏过程中的微裂缝缓慢扩展、劈裂裂缝快速发展、劈裂裂缝不断扩展等3个主要阶段,裂缝发展演化特点有显著的差异,每个阶段测得的z值、φ值变化情况与其对应的裂缝演化特征呈现出稳定的相关性;混凝土z值、φ值随着损伤程度的增大而增大,且两者增大速率一致;混凝土初始z值、φ值与强度之间存在一定线性相关关系。因此,混凝土z值、φ值等电化学参数可以用于检测混凝土裂缝演化和评估其内部损伤程度。
Aiming at the damage evolution of concrete crack and its detection, a new idea of crack detection or damage assessment based on impedance parameter of material is proposed based on AC impedance spectroscopy. Using the steel bar as the electrode, the impedance modulus (z value) and the phase angle value (φ value) of the concrete were taken as the parameters of the impedance characteristics of the material. The change of the impedance characteristic parameters of the concrete specimens during the splitting tensile test was measured by the MT4090 LCR measuring instrument law. According to the measurement results, the change rule of the damage evolution and development process of the concrete damage and the impedance characteristic parameters are analyzed. The experimental results show that there are three main stages in the process of splitting and delaminating, such as slow propagation of micro-cracks, rapid development of splitting cracks and continuous expansion of splitting cracks. There are significant differences in the development and evolution of cracks. The z The value of φ and the change of φ value showed a stable correlation with the corresponding evolution characteristics of the fractures. The z value and φ value of concrete increased with the increase of the damage degree, and the rate of increase of the two was consistent. The initial value of z, φ There is a certain linear correlation between value and intensity. Therefore, the electrochemical parameters of z value, φ value of concrete can be used to detect the evolution of concrete cracks and assess the degree of internal damage.