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Quantifying oxygen diffusion in bitumen films using molecular dynamics simulations

Gao, Y, Zhang, Y, Zhang, C, Liu, X and Jing, R (2022) Quantifying oxygen diffusion in bitumen films using molecular dynamics simulations. Construction and Building Materials, 331. ISSN 0950-0618

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Bitumen in asphalt pavements reacts slowly with atmospheric oxygen, resulting in oxidative ageing. This oxidative reaction is strongly dependent on the physical diffusion of the oxygen into the bitumen. This study aims to use molecular dynamics (MD) simulation to investigate the oxygen diffusion into the bitumen film and analyse the effects of anti-ageing compounds (AACs) on the oxygen diffusion. The MD diffusion simulations using a Polymer Consistent Force Field (PCFF) were conducted on a bitumen-air bi-layer model at different temperatures. Fick's second law was used to calculate the diffusion coefficient of the oxygen in the bitumen film. It is found that the oxygen diffusion coefficients ranged from 6.67 × 10−10 to 7.45 × 10−11 m2/s for the unmodified and AAC-modified bitumens at the simulating temperatures of 25, 50 and 100 °C. Irganox acid and DLTDP (Dilauryl thiodipropionate):furfural showed two different anti-aging mechanisms, i.e., reducing the oxygen physical diffusion and controlling the chemical oxidative reaction. Reducing the oxygen diffusivity by constructing a network in the bitumen to retard oxygen diffusion and increase the transport path is an efficient way to slow down the bitumen aging without the antioxidant consumption. This work proposed a MD-based computational approach, contributing to 1) determination of the oxygen diffusion coefficient of the existing bitumen that is extremely challenging for the experimental measurement and 2) instruction of developing new antioxidant.

Item Type: Article
Uncontrolled Keywords: 0905 Civil Engineering; 1202 Building; Building & Construction
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Divisions: Civil Engineering & Built Environment
Publisher: Elsevier BV
SWORD Depositor: A Symplectic
Date Deposited: 19 Jun 2023 12:56
Last Modified: 19 Jun 2023 13:00
DOI or Identification number: 10.1016/j.conbuildmat.2022.127325
URI: https://researchonline.ljmu.ac.uk/id/eprint/19939

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