Adhesive Characteristic and Mechanism of Ballastless Track Sealant in Hydrolysis Condition

Abstract

The current evaluation method cannot predict accurately the hydrolysis resistance of sealants applied in ballastless slab track. And the degradation mechanism of sealant in hydrolysis condition has not been researched systemically. In this paper, the hydrolysis resistance of different sealants was researched with the aid of the self-developed direct tensile test method. The atomic force microscope was employed to analyze the microadhesion force on the surface of sealants, and thereby the correlation between macrobehavior and the micro-mechanism of sealants during hydrolysis was established. Results showed that the characteristics of the interface between sealants and substrates are reduced after hydrolysis, and that sealants with higher soft-segment content have good resistance to hydrolysis. Reduction of the bonding area after hydrolysis is also an important factor in the reduction of the characteristics of the adhesive interface. The micro-adhesion force of soft segments shows a fluctuating reduction tendency, and that of hard segments reduces more significantly during hydrolysis. The micro-adhesion force has good correlation with the maximum tensile force, but a poor correlation with failure displacement. The maximum tensile force is proved to be an optimal evaluation index in determining the hydrolysis resistance of sealants.

Influence on Polyurethane Synthesis Parameters Upon the Performance of Base Asphalt

“…Ordinary asphalt and its mixture can no longer meet the requirements of modern transportation and road surface structure, due to the occurrence of such problems. At present, the asphalt binder is usually modified by a polymer to improve the performance of the asphalt binder (Zhang et al, 2018;Xu et al, 2019;Jin et al, 2020;Xue et al, 2020). However, as a result of polymers in storage and use process factors such as heat, light, oxygen, the effect of aging degradation (Cong et al, 2019), and the density of polymer and asphalt, relative molecular mass, solubility, and other large differences, which leads to poor storage stability of polymer-modified asphalt and easy separation, the use of polymer-modified asphalt performance is reduced (Shirzad et al, 2020).…”