The Self-Healing Performance of Carbon-Based Nanomaterials Modified Asphalt Binders Based on Molecular Dynamics Simulations

Yan Gong,Jian Xu,Jun-Hua Cai,Er-Hu Yan

doi:10.3389/fmats.2020.599551

Yan Gong, Jian Xu + Show 2 more

Open Access

https://doi.org/10.3389/fmats.2020.599551

Copy DOI

Abstract

In this study, the molecular dynamics simulation was used to explore the effects of carbon-based nanomaterials as binder modifiers on self-healing capability of asphalt binder and to investigate the microscopic self-healing process of modified asphalt binders under different temperature. An asphalt average molecular structure model of PEN70 asphalt binder was constructed firstly. Further, three kinds of carbon-based nanomaterials were added at three different percentages ranging from 0.5 to 1.5% to the base binder to study their effects on the self-healing capability, including two carbon nanotubes (CNT1 and CNT2) and graphene nanoflakes. Combining with the three-dimensional (3D) microcrack model to simulate the asphalt self-healing process, the density analysis, relative concentration analysis along OZ direction, and mean square displacement analysis were performed to investigate the temperature sensitive self-healing characters. Results showed that the additions of CNTs were effective in enhancing the self-healing efficiency of the plain asphalt binder. By adding 0.5% CNT1 and 0.5% CNT2, about 652% and 230% of the mean square displacement of plain asphalt binder were enhanced at the optimal temperatures. However, the use of graphene nanoflakes as an asphalt modifier did not provide any noticeable changes on the self-healing efficiency. It can be found that the self-healing capability of the asphalt was closely related to the temperature. For base asphalt, the self-healing effect became especially high at the phase transition temperature range, while, for the modified asphalt, the enhancement of the self-healing capability at the low phase transition temperature (15°C) became negligible. In general, the optimal healing temperature range of the CNTs modified asphalt binders is determined as 45–55°C and the optimal dosage of the CNTs is about 0.5% over the total weight of the asphalt binder. Considering the effect of carbon-based nanomaterials on the self-healing properties, the recommended carbon-based nanomaterials modifier is CNT1 with the aspect ratio of 1.81.

Highlights

In recent decades, the traffic load supported by asphalt road pavements has significantly increased
The average molecular structure models of the PEN70 asphalt binder were firstly constructed based on the measured structure parameters through a series of physical chemical experiments
The dynamics simulation of the 3D microcrack model was conducted, and the volume parameter of the amorphous cell changed to 34.58 Å3 × 34.58 Å3 × 86.36 Å3 after 150 ps (PEN70 asphalt binder with 0.5% CNT1)

Summary

INTRODUCTION

The traffic load supported by asphalt road pavements has significantly increased. In this study, the effectiveness of using three different types of carbon-based nanomaterials (CNT1, CNT2, and GNF) on improving the selfhealing performance of asphalt binder was investigated. The asphalt binder with the penetration grade of 70 (named PEN70) was selected to construct the corresponding average molecular model and investigate the temperature sensitive self-healing performances. Two types of carbon-based nanomaterials (CNT and GNF) were used as the modifiers in the PEN70 asphalt binder to enhance the mechanical properties and achieve the self-healing capacity. The simulated temperature was set within 15–55°C, including 288.15 K (15°C), 298.15 K (25°C), 308.15 K (35°C), 318.15 K (45°C), and 328.15 K (55°C)

RESULTS AND DISCUSSION

CONCLUSION

Conclusions are listed as follows:

DATA AVAILABILITY STATEMENT