Xia Yu, Lin Juntao, Chen Zongwu, Cai Jun, Hong Jinxiang, Zhu Xiaobin
Faculty of Engineering, China University of Geosciences (Wuhan), Wuhan 430074, China.
Key Laboratory of Road Structure and Material of Ministry of Transport (Changsha), Changsha University of Science & Technology, Changsha 410205, China.
Materials (Basel). 2022 Jun 24;15(13):4476. doi: 10.3390/ma15134476.
This paper aims to investigate the fatigue cracking evolution of cold recycled asphalt mixtures with asphalt emulsion (CRME) under different curing times. The fatigue cracking model of CRME based on damage mechanics and fracture mechanics was analyzed according to the fatigue loading curve. Firstly, the fatigue cracking evolution of CRME was studied through an SCB strength test and SCB fatigue test. Then, the fatigue damage mechanics were used to establish a nonlinear fatigue cracking model, and the damage degree of CRME at the initial cracking point was determined. The Paris formula was used to characterize the law of fatigue crack propagation. Finally, the microstructure of CRME was observed by scanning electron microscopy (SEM) with the backscattering method. The results indicate that the initial cracking point appears at around 60% of the fatigue life according to the SCB fatigue test by means of image analysis. The damage variable was obtained through the cracking model, and the value of the damage variable was determined as 0.06-0.17 at the initial cracking point. In addition, the Paris formula showed that the crack growth of CRME can be reflected by the stress intensity factor and correlative parameters. Moreover, cement hydration products were mixed with the asphalt membrane to form a denser spatial structure during the curing process, which may provide higher fatigue performance of CRME. This research may provide a theoretical reference for studying the fatigue cracking behavior of CRME.
本文旨在研究不同养护时间下乳化沥青冷再生混合料（CRME）的疲劳开裂演变。根据疲劳加载曲线，分析了基于损伤力学和断裂力学的CRME疲劳开裂模型。首先，通过SCB强度试验和SCB疲劳试验研究了CRME的疲劳开裂演变。然后，运用疲劳损伤力学建立了非线性疲劳开裂模型，并确定了CRME在初始开裂点的损伤程度。采用巴黎公式表征疲劳裂纹扩展规律。最后，采用背散射法通过扫描电子显微镜（SEM）观察了CRME的微观结构。结果表明，通过图像分析的SCB疲劳试验显示，初始开裂点出现在疲劳寿命的60%左右。通过开裂模型得到了损伤变量，初始开裂点处损伤变量的值确定为0.06 - 0.17。此外，巴黎公式表明，CRME的裂纹扩展可以用应力强度因子和相关参数来反映。而且，在养护过程中水泥水化产物与沥青膜混合形成了更致密的空间结构，这可能为CRME提供更高的疲劳性能。本研究可为研究CRME的疲劳开裂行为提供理论参考。
