Evaluation of Deterioration of Concrete by Acoustic Emission Method

近年来，声发射技术在混凝土劣化诊断工具中的应用备受关注。研究了受压加载过程中冻融作用和碱硅反应引起的劣化混凝土声发射特性。将试验结果与常规的混凝土劣化评价参数进行了比较，如抗压强度、杨氏模量和膨胀特性。同时，研究了水灰比、混凝土龄期、初始加载速率、初始加载后的储存条件和期限等条件下混凝土的Kaiser效应。试验结果表明，低应力水平下的声发射计数率随混凝土发展的劣化程度而增大，在最终破坏过程中的声发射计数率特征与相同抗压强度下未劣化混凝土的声发射计数率特征基本相同。特别是在混凝土初载龄期较低、初载后储存期较长的情况下，混凝土中的Kaiser效应观察不明显。这些现象被认为是评价混凝土劣化的有效方法。

Recently, Applications of acoustic emission (AE) technology to diagnostic tools attract great attention for the evaluation of deterioration of concrete.In this study, AE characteristics of deteriorated concrete due to freezing and thawing actions or alkali silica reaction, during compressive loading were investigated. The results were compared with conventional parameters for evaluating the deterioration of concrete, such as compressive strength, Young's modulus and expansion characterisics. At the same time, Kaiser effect in concrete under several conditions of water cement ratio, concrete age, rate of initial loading and storing condition and term after initial loading were investigated.The experimental results show that AE count rate in low stress lovel becomes large according to the deterioratin of concrete develope, and the AE count rate characteristics in the process of final failure are almost the same as that of the non-deteriorated concrete having the same compressive strenght. Kaiser effect in concrete can not be observed clearly especially in the case that the age of concrete at initial loading is low and the term of storing arter initial loading is long. These phenomena are considered to be used effectively for evaluation of deterioration of concrete.