ROSE bitumen: Mesoscopic model of bitumen and bituminous mixtures

Abstract

We present a mesoscopic model for bitumen and bituminous mixtures. The model, which is based on dissipative particle dynamics, consists of different dynamical entities that represent the different characteristic time scales. Through the stress relaxation function, the mechanical properties of the model are investigated. For pure bitumen, the viscosity features super-Arrhenius behavior in the low-temperature regime in agreement with experimental data. The frequency-dependent viscoelastic properties show purely viscous behavior at low frequencies with increasing elasticity and hardening at higher frequencies, as expected. The model dynamics are analyzed in the framework of longitudinal hydrodynamics. The thermal process is two orders of magnitude slower than the attenuation of the density-wave propagation; hence the dynamic structure factor is dominated by a sharp Rayleigh peak and a relatively broad Brillouin peak. The model is applied to study triblock-copolymer-modified bitumen mixtures. Effects of the polymer concentration and end-block interactions with the bitumen are investigated. While the polymer concentration has an effect on the mechanical properties, the effect of increasing repulsive interactions between the bitumen and the polymer end-blocks is much more dramatic; it increases the viscosity of the mixture and shifts the onset of the elastic behavior to lower frequencies. For increased repulsion, the polymer end-blocks form small clusters that can be connected by a dynamic polymer backbone network. A simple Flory-Huggins analysis reveals the onset of segregation of the end-blocks in the bitumen mixture in agreement with the simulation data. Hence the changed mechanical properties are due to the emergence of large-scale structures as the repulsion is increased, which conforms to known mechanisms of microphase separation in polymer-modified bitumens.

Research on the synergistic modification effect and the interface mechanism of GO/SBS compound-modified asphalt based on experiments and molecular simulations

“…As the exact chemical composition of the asphalt cannot be determined, researchers have used representative molecules in molecular dynamics (MD) simulations to model the behavior of asphalt. Hansen and Lemarchand et al proposed a four-component united-atom molecular model of asphalt and described methods for analyzing the dynamics of asphalt models by means of mean-square displacement, stress autocorrelation function and rotational relaxation 34 , 35 . The mesoscopic model and the 12-component model for asphalt have also been proposed by Greenfield and Li et al which are widely applied to MD simulations of asphalt 36 , and the characteristics of the models agreed well with the elemental and saturate-aromatic-resin-asphaltene (SARA) analysis results specific to each binder 37 .…”

A Simple Scheme for Extraction of Asphaltenes from Asphalt at Room Temperature

“…The physical properties of asphalt such as penetration, softening point, ductility, high temperature stability and rutting resistance are great influenced by the content and structures of asphaltene [3]. It is generally believed that asphalt has a colloid structure with asphaltene as the core [4]. To analyze the aggregate structure of asphaltenes and to change the asphaltene content in asphalt, it is necessary to extract asphaltenes from asphalt [5].…”

The Influence of Extractant Composition on the Asphaltenes Extracted from Asphalt

“…Asphalt is one kind of coating materials widely used for roof waterproofing, interface bonding and surface layers of high-grade highways [1,2]. Asphalt has a complex chemical structure and composition [3][4][5]. According to the different solubility, it can be divided into four components: saturate, aromatic, resin and asphaltene [1,5,6].…”