Shan Yuchuan, Zheng Shuguang, Zhang Xuefeng, Luo Wei, Mao Jingda, Kong Deyu
Zhejiang University of Technology Engineering Design Group Co., Ltd., Hangzhou 310014, China.
College of Architecture & Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, China.
Materials (Basel). 2018 Nov 13;11(11):2259. doi: 10.3390/ma11112259.
The cement and asphalt mortar (CA mortar) used in the China Railway Track System (CRTS) I ballastless slab track may encounter a coupling fatigue effect under the high-frequency vibration, load and high-and-low temperature cycles, and the deterioration under fatigue may happen during service of the high-speed railway. In this study, the performance degradation and its mechanism of the CA mortar with and without polymer emulsion incorporated under the coupling fatigue effects of the high-frequency vibration, load and temperature were studied by using an anti-fatigue testing device specially developed for the CA mortar used in the ballastless slab track of the high-speed railway. The results showed that the deformation capacity of the CA mortar for CRTS I slab ballastless slab track decreased after fatigue test under simulated service environment, presenting a typical brittle characteristic and an obvious reduction of the ductility and toughness. The Scanning Electron Microscopy (SEM) observation and the mercury intrusion porosimetry (MIP) analysis showed that the volume of the macropore decreased whereas that of the micropore increased after the fatigue test. The asphalt in the hardened CA mortar revealed a softening and migration from the bulk paste to fill the pore and make the structure denser and even ooze out of the CA mortar under the high-frequency vibration and high temperature. Through incorporating the polymer emulsion, the anti-fatigue property of the CA mortar was obviously improved, which can prevent the CA mortar from losing its elastic adjustment function too early. Though increase of the strength and elastic modulus for the CA mortar after severe service is beneficial to the stability of train running, the comfort level and safety of the train operation may decline due to the gradual reduction of the ductility & toughness and the gradual loss of the elastic damping adjustment function of the CA mortar between the base concrete slab and the track slab.
中国铁路板式无砟轨道（CRTS）I型中使用的水泥乳化沥青砂浆（CA砂浆）在高频振动、荷载以及高低温循环作用下可能会遭遇耦合疲劳效应，并且在高速铁路运营期间，疲劳作用下的劣化可能会发生。在本研究中，通过使用专门为高速铁路板式无砟轨道中使用的CA砂浆开发的抗疲劳试验装置，研究了在高频振动、荷载和温度耦合疲劳作用下，掺加和未掺加聚合物乳液的CA砂浆的性能退化及其机理。结果表明，在模拟服役环境下进行疲劳试验后，CRTS I型板式无砟轨道CA砂浆的变形能力降低，呈现出典型的脆性特征，延性和韧性明显降低。扫描电子显微镜（SEM）观察和压汞法（MIP）分析表明，疲劳试验后，大孔体积减小而微孔体积增加。硬化CA砂浆中的沥青出现软化，并从整体浆体中迁移以填充孔隙，使结构更致密，甚至在高频振动和高温下从CA砂浆中渗出。通过掺入聚合物乳液，CA砂浆的抗疲劳性能明显提高，这可以防止CA砂浆过早失去弹性调节功能。虽然CA砂浆在经历严酷服役后强度和弹性模量的增加有利于列车运行的稳定性，但由于CA砂浆的延性和韧性逐渐降低以及其在基础混凝土板和轨道板之间的弹性阻尼调节功能逐渐丧失，列车运行的舒适度和安全性可能会下降。
