Molecular Interaction Mechanism between Aromatic Oil and High-Content Waste-Rubber-Modified Asphalt

Abstract

High-content waste-rubber-modified asphalt (HRMA) has high viscosity and poor storage stability. HRMA not only improves the properties of road asphalt, but also reduces the environmental pollution caused by waste tires. Enhancing the molecular interaction of waste rubber and asphalt is key to making full use of HRMA. In this paper, aromatic oil was used as the activator for waste rubber. The molecular interaction mechanism between aromatic oil and HRMA was investigated. The radial distribution function, diffusion coefficient, free volume, solubility parameter, and shear viscosity were calculated through molecular simulations. Storage stability, micromorphology, and adhesive force were measured via experiments. The adhesive force of HRMA−1 (4.9 nN) was lower than that of RMA (6.2 nN) and HRMA−2 (5.8 nN). The results show that aromatic oil can promote the dispersion of waste rubber, making the storage of asphalt systems stable. There exists a strong electrostatic force between rubber and asphaltenes and an intermolecular force between rubber and aromatic oil or aromatics, which makes the aromatic oil and aromatics of parcel rubber molecules and waste rubber highly soluble in asphalt. Molecular simulations confirmed the molecular interaction between rubber and aromatic oil, and aromatic oil was shown to reduce the viscosity of HRMA.