基于三点弯曲试验的聚丙烯塑料颗粒混凝土 声发射分析*

为探讨掺入聚丙烯塑料颗粒(PP)对混凝土疲劳损伤的影响，以不同塑料颗粒掺量Wf (0、10%和20%)混凝土为研究对象，采用声发射技术，开展一系列三点弯曲疲劳试验。试验结果表明：掺入塑料颗粒后，混凝土疲劳寿命增大，断裂能增大，可承受的最大荷载降低，但挠度增大，塑性变形能力增强；AE（Acoustic Emission）定位的损伤源主要集中在跨中，首次峰值荷载前，AE事件偏少，AE定位可识别的内部疲劳损伤点较少，当接近疲劳破坏阶段，AE信号源急剧增加，且随着Wf越大，AE事件数量明显减少，AE事件主要出现在循环荷载波谷处；掺入塑料颗粒后，声发射信号次数显著降低，持续时间更短，且随着Wf的增加，声发射信号次数进一步降低。掺入PP塑料颗粒有助于缓解混凝土内部疲劳损伤，延长其疲劳寿命。

Acoustic emission analysis of polypropylene plastic concrete based on three-point bending test

To investigate the effect of adding polypropylene plastic particles (PP) on fatigue damage of concrete, a series of three-point bending fatigue tests were conducted using acoustic emission technology with different plastic particle dosages of Wf (0, 10%, and 20%) in concrete. The experimental results show that after adding plastic particles, the fatigue life of concrete increases, the fracture energy increases, and the maximum load that the specimen can withstand decreases, but the deflection increases and the plastic deformation ability enhances; The damage sources of AE localization are mainly concentrated in the mid span area. Before the first peak load, there are fewer AE events, and there are fewer fatigue damage points inside the concrete that can be identified by AE localization. As the fatigue failure stage approaches, the number of AE signal sources increases sharply, and as Wf increases, the number of AE events is significantly lower; AE events mainly occur at the trough of cyclic loading. After adding plastic particles, the number of acoustic emission signals significantly decreases and the duration is shorter. Moreover, with the increase of Wf, the number of acoustic emission signals further decreases.