Yang Kang, Li Dongxue, He Zhaoyi, Zhou Hanlin, Li Jiaqi
School of Civil Engineering, Chongqing Jiaotong University, Chongqing 400074, China.
College of Traffic & Transportation, Chongqing Jiaotong University, Chongqing 400074, China.
Materials (Basel). 2021 Feb 12;14(4):881. doi: 10.3390/ma14040881.
In this study, asphalt concrete specimens were subjected to a semicircle bending test at -10 °C to simulate the process of the development of cracks in asphalt concrete at low temperature. The acoustic emission parameters were collected during the test, the variation characteristics of acoustic emission parameters were analyzed, and the peakedness value was introduced to evaluate the damage of asphalt concrete. The dynamic evolution of fracture development was analyzed by periods with acoustic emission source location. The results indicate that the damage of asphalt mixtures shows an obvious brittle characteristic at low temperature, acoustic emission signals mainly originate from the crack damage caused by tensile stress, and the strength and number of signals can reflect the degree of crack development. Based on acoustic emission parameters and load curves, the cracking damage of asphalt concrete at low temperature in this study can be divided into three periods: a calm period, a stable development period, and a rapid fracture period. The crack point occurred and propagated upward rapidly in the rapid fracture period. During this period, acoustic emission parameters such as ringing count, acoustic emission energy, and amplitude increased suddenly; furthermore, the peakedness value reached its peak in this period and corresponded well with the low-temperature damage of asphalt concrete. Acoustic emission source location technology can track position of crack points and the propagation path of cracks, reflecting the dynamic evolution process of asphalt concrete crack damage at low temperature.
在本研究中，对沥青混凝土试件在-10℃下进行半圆弯曲试验，以模拟低温下沥青混凝土裂缝发展的过程。在试验过程中采集声发射参数，分析声发射参数的变化特征，并引入峰值度来评估沥青混凝土的损伤。通过声发射源定位按时间段分析裂缝发展的动态演化。结果表明，沥青混合料在低温下的损伤表现出明显的脆性特征，声发射信号主要源于拉应力引起的裂缝损伤，信号的强度和数量能够反映裂缝发展程度。基于声发射参数和荷载曲线，本研究中沥青混凝土低温下的开裂损伤可分为三个阶段：平静阶段、稳定发展阶段和快速断裂阶段。在快速断裂阶段，裂纹点出现并迅速向上扩展。在此期间，振铃计数、声发射能量和幅值等声发射参数突然增大；此外，峰值度在此阶段达到峰值，与沥青混凝土的低温损伤吻合良好。声发射源定位技术能够追踪裂纹点位置和裂缝扩展路径，反映沥青混凝土低温裂缝损伤的动态演化过程。
