自愈合混凝土损伤演化声发射监测及其评价技术

自愈合混凝土能较大程度地提高混凝土的极限承载力.针对自愈合混凝土损伤缺乏有效研究手段的现状,提出用声发射技术来监测它的损伤演化.通过自愈合混凝土梁三点弯曲试验,对它的损伤全过程进行了声发射监测.通过声发射计数能够准确地判断自愈合混凝土裂纹的开裂、扩展及其损伤演化过程,它的包络曲线和荷载曲线具有良好的对应关系.运用凯塞(Kaiser)效应和费利西蒂(Felicity)比能正确判断愈合的优劣情况.最后,对自愈合混凝土损伤演化的各个阶段声发射波形进行小波分析,通过小波奇异检测技术提取出各自的特征波形,并分析其频率分布范围,进一步分析了损伤的内在成因,为自愈合混凝土损伤类型提供了一种新的判据和测试方法.

Damage evolution monitoring and evaluation of self-repairing concrete using acoustic emission technique

The concrete ultimate load capacity is improved through self-repairing.Because there is a dearth of studies regarding damage evolution of self-repairing concrete,acoustic emission(AE) technology is presented to monitor its evolution process.The full-process damage of self-repairing concrete is monitored under three-point bending beam testing using AE technique.It is found that the initiation,propagation and evolution of self-repairing concrete cracks can be described using AE hits.Firstly,the corresponding relationship between the AE hits and load is testified by comparing with their embraceable curve.Secondly,the repairing effect of self-repairing concrete is judged using Kaiser effect and Felicity ratio.Finally,the different damage types of AE waveforms of self-repairing concrete are extracted and analyzed using wavelet singularity theory.The damage causes are analyzed according to the waveform frequency distribution.The testing results show the AE technique can provide a new testing method for self-repairing concrete damage judgment.