Atomistic-scale investigation of self-healing mechanism in Nano-silica modified asphalt through molecular dynamics simulation
Zhengwu Long, Xianqiong Tang, Nanning Guo, Yanhuai Ding, Wenbo Ma, Lingyun You, Fu Xu
Abstract
Abstract As one of the most widely used nanomaterials in asphalt modification, the nano-silica (nano-SiO 2 ) can significantly improve the self-healing behavior of asphalt eco-friendly. However, understanding of the self-healing mechanism of nano-SiO 2 in asphalt is still limited. The objective of the study is to reveal the self-healing mechanism of nano-SiO 2 in asphalt by using molecular dynamics (MD) simulations from the nanoscale. A 10 Å (Å) vacuum pad was added between the two same stable asphalt models to represent the micro-cracks inside the asphalt. The self-healing process of virgin asphalt, oxidation aging asphalt, and nano-SiO 2 modified asphalt was studied using density evolution, relative concentration, diffusion coefficient, activation energy, and pre-exponential factor. The simulation results conclude that nano-SiO 2 improves the self-healing ability of asphalt by increasing the diffusion rate of molecules with aromatic structures without alkyl side chains and molecules with structures with longer alkyl chains. The self-healing capability of asphalt may be principally determined by the diffusion of light components such as saturate, while nano-SiO 2 only plays an inducing role. The research findings could provide insights to understand the self-healing mechanism of nano-SiO 2 in asphalt for promoting the sustainability of bitumen pavements while increasing their durability. Graphical abstract