Field evaluation of LDHs effect on the aging resistance of asphalt concrete after four years of road service

摘要

More than ten kilometers of test road with the layered double hydroxides (LDHs) modified asphalt binder was constructed to field evaluate the LDHs effect on the aging resistance of asphalt concrete, after four years of road service, asphalt concrete specimens were collected from the compared road (without LDHs), test road (with LDHs) and tunnel (without LDHs), respectively. Then, 1.5 cm surface mixture of every specimen was cut into three layers to reclaim the asphalt binders, labeled as layer 1, layer 2 and layer 3 from surface to interior. The chemical structures and oxygen contents of reclaimed asphalt binders were investigated by the Fourier infrared spectrometer (FTIR) and elemental analyzer, respectively. Meanwhile, the dynamic shear rheometer (DSR) was conducted to study the rheological performance such as complex modulus, phase angle and viscosity of reclaimed asphalt binders. In addition, the three points bending test was conducted by universal testing machine (UTM) at the temperature of -10 degrees C, the parameters of bending strength (R-B), bending strain (epsilon(B)) and bending modulus (S-B) were used to evaluate the low temperature crack resistance of asphalt concrete from all these three sections respectively. The results show that, with the increase of pavement depth, the aging degree of asphalt concrete tends to decrease; the aging depth of asphalt pavement in field is within 1.0 cm. LDHs can not only decrease the aging rate of the surface asphalt concrete, but also decrease the rate of the aging diffuses into the inner of asphalt pavement, the chemical structures and technical performance of LDHs modified asphalt binders are closer to the initial status of which. The values of R-B and S-B of asphalt concretes from both test road and tunnel are lower than that of asphalt concretes from compared road, meanwhile, the values of epsilon(B) of asphalt concretes from test road and tunnel are higher. The low temperature crack resistances of asphalt concretes of tunnel and test road are much better than that of compared road. Hence, LDHs can significantly improve the aging resistance of asphalt concrete in field. (C) 2019 Elsevier Ltd. All rights reserved.