Asphalt modified materials and modification mechanism have always been focused in the research of road materials. Methylene diphenyl diisocyanate (MDI), as a common chemical raw material, when used to modify asphalt can greatly improve the high-temperature performance of asphalt. The viscosity modification mechanism of MDI modified asphalt needs further study. Based on this, the matrix asphalt and MDI modified asphalt models were constructed and confined sheared through molecular dynamics simulation to investigate the effect of the macromolecules of the nucleophilic addition reaction on the modification. It was found that the viscosity of matrix asphalt changes little with the increase of temperature. The law of MDI modified asphalt with double pyrrole behave similarly except that the shear viscosity of latter was larger at each temperature. However, the two models containing asphaltene-phenol both showed higher viscosity-temperature sensitivity at temperatures of 368K-383K. Most of the components that play a role in increasing viscosity in MDI modified asphalt may be double phenol or phenol-pyrrole.

Asphalt;molecular dynamics;Viscosity;MDI