Methods for Detection and Diagnosis of Inner Defects in Concrete Structures

本研究首先分析了混凝土结构内部缺陷检测与诊断的无损检测方法的特点，然后研究了其在结构中的适用性，取得了以下主要研究成果.结合混凝土半电池电位、极化电阻和电阻的测量，探讨了X射线法检测海洋环境下钢筋混凝土梁试件内部缺陷的适用性。结果表明，这些方法可用于钢筋锈蚀程度的检测和诊断.采用X射线法和超声波波速测量相结合的方法，对实际尺寸的钢筋混凝土内部人工缺陷试件进行了检测。试验结果表明了这些方法的适用性。在使用超声脉冲速度的情况下，也表明数据的分散性比其绝对值更重要.结果表明，超声脉冲波速与回弹仪联合检测可以较好地评价水桥结构混凝土在施工后较长时间内的抗压强度.随着混凝土首次加载龄期的提前和加载时间的延长，声发射中的凯塞效应变得越来越不明显。在劣化混凝土试件中，AE的发生在加载的早期阶段更为显著。

In this research, characteristics of non-destructive testing methods used for detection and diagnosis of inner defects in concrete structures were firstly examined, and then their applicability to structures was investigated.The main results obtained from this research works are as follows.1. The applicability of X-ray method to the detection of inner defects in reinforced concrete beam specimens exposed to marine environment was examined together with the measurements of half cell potential, polarization resistance and electric resistance of concrete. It was indicated that these methods could be used for detection and diagnosis of the degree of reinforcement corrosion.2. X-ray method together with the measurement of ultrasonic pulse velocity were applied to practical sized reinforced concrete specimens which had artificial inner defects. From the tests results, the applicability of these methods was indicated. In case of using ultrasonic pulse velocity, it was also indicated that the scattering of data was rather important than their absolute values of the evaluation of inner dafects.3. It was shown that the compressive strength of concrete in water bridge structures after a long time elapsed from construction could be well estimated by the combination of ultrasonic pulse velocity and rebound hammer.4. Kaiser effect in acoustic emission became more obscure as the age of concrete at the first loading became earlier and also as the time from the first loading became longer. In deteriorated concrete specimens, the occurrence of AE was observed more significantly in an earlier stage of loading.