Performance of Asphalt Materials Based on Molecular Dynamics Simulation: A Review

Abstract

With the rising performance demands in road engineering, traditional experiments often fail to reveal the microscopic mechanisms behind asphalt behavior. Molecular dynamics (MD) simulation has emerged as a valuable complement, enabling molecular-level insights into asphalt's composition, structure, and aging mechanisms. This review summarizes the recent advances in applying MD to asphalt research. It first outlines molecular model construction approaches, including average models, three- and four-component systems, and modified models incorporating SBS, SBR, PU, PE, and asphalt-aggregate interfaces. It then analyzes how MD reveals the key performance aspects-such as high-temperature stability, low-temperature flexibility, self-healing behavior, aging processes, and interfacial adhesion-by capturing the molecular interactions. While MD offers significant advantages, challenges remain: idealized modeling, high computational demands, limited chemical reaction simulation, and difficulties in multi-scale coupling. This paper aims to provide theoretical insights and methodological support for future studies on asphalt performance and highlights MD simulation as a promising tool in pavement material science.

Keywords: aging; asphalt binder; asphalt modifiers; interfacial adhesion; molecular dynamics simulation; molecular modeling; self-healing.

Figure 1

Analysis of related papers: (a) chart of the number of years of the publication literature (b) frequency of citations (c) number of papers by country (d) number of document types.

Figure 2

Eight average molecular models for bitumen binders [2,15].

Figure 3

Molecular structures of three components of asphalt binder. (a) Asphaltenes; (b) resins; (c) n-C22 (n-docosane) [22].

Figure 4

Four-component molecular model of asphalt. (a) Pyrrole; (b) molecules derived from maltene condensation reactions; (c) 1,7-dimethylnaphthalene; (d) n-docosane (n-C22); (e) virgin asphalt [6].

Figure 5

Four-component 12-molecule model of asphalt [31].

Figure 6

AAA-1 molecular model of asphalt [32].

Figure 7

Twenty-molecule model of asphalt [30].

Figure 8

Molecular model of the SBS modifier [38].

Figure 9

Molecular models of SBS modifiers with different block ratios [40].

Figure 10

SBR molecular model [46].

Figure 11

Crystal cell model of asphalt and the SBR modifier [47].

Figure 12

PU molecular model [49].

Figure 13

Molecular model of PU [50].

Figure 14

Waste polyurethane molecular chain [51].

Figure 15

PE molecular model with different degrees of polymerization (a) 6 (b) 12 (c) 24 (d) 30 (e) 42 (f) 78 [53].

Figure 16

PE modifier model [54].

Figure 17

Graphene/RPE–modified asphalt models [55].

Figure 18

Unit cells of silicon dioxide and calcium oxide [61,62].

Figure 19

Unit cell structure and lattice parameters of calcite [63].

Figure 20

Mineral–bitumen interface systems after MD simulations: (a) quartz–asphalt model; (b) calcite–asphalt model; (c) albite–asphalt model; (d) microcline–asphalt model; and (e) locally enlarged interface structure for microcline–asphalt model [64].

Figure 21

Physical modulus of nano-ZnO/SBS-modified asphalt: elastic modulus (E), bulk modulus (K), and the shear modulus (G) [9].

Figure 22

Specific volume versus temperature curve of the AAA-1 asphalt model [75].

Figure 23

Aromatic carbon content of aromatics (Ars), resins (Rs), and asphaltenes (Ass) [76].

Figure 24

Self-healing model of asphalt [89].

Figure 25

Formation of functional groups in aged asphalt [60].

Figure 26

Short-term and long-term aging behavior of asphalt components [97].

Figure 27

Molecular structures of five asphalt models: (a) asphaltene molecules (O: red; N: blue; S: yellow; C: gray; H: white); (b) resin molecules (O: red; N: blue; S: yellow; C: gray; H: white); (c) aromatic molecules (O: red; C: gray; H: white); (d) saturate molecules (C: gray; H: white) [98].

Figure 28

Aged SBS modifier molecular model [102].

Figure 29

Aged SBS-modified asphalt molecular model [104].

Figure 30

Adhesion and healing model of aged asphalt–aggregate interface [60].

Figure 31

Comparison of the MSD of SARA fractions in virgin and aged asphalt for (a) asphaltene; (b) aromatic; (c) resin; and (d) saturate [100].

Figure 32

Interaction energy and its component predicted via MD simulation [115].

Figure 33

Work of adhesion between asphalt and aggregates [117].

Figure 34

Percentage of water intrusion at the interface of asphalt and different aggregates [119].