Viscosity Reduction Mechanism and Rheological Properties of Ethylene-Bis-Stearamide and Crumb Rubber Modified Asphalt

Abstract

This study investigates the effect of ethylene-bis-stearamide (EBS) on viscosity reducing of crumb rubber modified asphalt (CRMA) and explores the interaction mechanism via molecular dynamics simulation (MD), microscope method and rheological experiment. It is confirmed that the EBS play an important role in reducing the viscosity of ethylene-bis-stearamide and crumb rubber modified asphalt (EBS-CRMA), especially when the content is within 3%. The micro morphology and MD results showed that the EBS is coating on rubber and asphaltenes and then forming lubrication film, which is the main reason leading to the viscosity decrease of EBS-CRMA. Additionally, other factors also have significant effect in reducing the viscosity of EBS-CRMA, including the more uniform distribution of asphaltenes, the enhanced diffusion ability of saturates and resins, the reduction of hydrogen bonds and soluble substances within asphalt phase. When EBS content exceeds 3%, the influence on viscosity of EBS-CRMA is not obvious with the EBS content continuously increasing. It can be concluded from Fourier Transform Infrared (FTIR) Spectrometer and MD results that the molecular aggregation, the concentration increase of intermolecular hydrogen bonds and the diffusion ability decrease of EBS-CRMA molecular system are main reasons. Meanwhile, the coating effect of EBS and soluble substances concentration within asphalt phase are limited as the EBS content over 3%.