Low-Temperature Performance of Asphalt Mixtures Modified by Microencapsulated Phase Change Materials with Various Graphene Contents

Yong-Xiang Ren,Pei-Wen Hao

doi:10.3390/coatings12020287

Yong-Xiang Ren, Pei-Wen Hao

Open Access

https://doi.org/10.3390/coatings12020287

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Journal: Coatings	Publication Date: Feb 21, 2022
Citations: 8	License type: CC BY 4.0

Affiliation: Chang'an University, Xuchang University

Abstract

Microencapsulated phase change materials (PCMs) added to conventional ones can store excessive heat energy and reduce thermal stresses. In this study, melamine–formaldehyde resin phase change microencapsulated PCMs, with different contents of graphene (CG), were added to asphalt mixtures, in order to reduce their low-temperature cracking, induced by thermal stresses. Low-temperature and heat-conducting/storing performance of the obtained mixtures was examined via beam bending tests, semi-circular bending low-temperature performance tests, thermal conductivity tests and volume-specific heat capacity tests. Besides, the prepared asphalt mixtures’ water stability and high-temperature stability values were obtained via freeze-thaw splitting and wheel tracking tests. The low-temperature performance of PCM-modified asphalt mixtures was evaluated via their bending strain energy densities, with one of the PCM-modified asphalt mixtures, namely CGMFPCM3, synthesized by the authors, was 1.7 times higher than that of the common asphalt mixture. Although the dynamic stability of all three PCM-modified mixtures was deteriorated by 68, 50, and 20% compared to the common one, that of CGMFPCM3 still complied with the standard requirement. Thermal conductivity and volume-specific heat capacity of the asphalt mixture at 278.15 K was enhanced by 5 and 43%, respectively, after adding CGMFPCM3. It is recommended for reducing the temperature variation-induced cracking in the asphalt pavement. Thermal conductivity and volume-specific heat capacity can be used for evaluating the temperature-regulating performance of asphalt mixtures.

Highlights

The mechanical and physical properties of asphalt and its mixtures strongly depend on temperature variations
Some test results revealed that the direct addition of phase change materials (PCMs) to an asphalt matrix can deteriorate the technological performance of modified asphalt [2,3,4] or modified asphalt mixtures [5,6,7,8], due to poor bonding between PCMs and the material matrix
Using low-temperature performance tests of the asphalt mixture, via the semi-circular bending (SCB) method described in Section 2.2.1, the fracture energy Gf, the fracture toughness KIC and the stiffness S were measured for evaluating the low-temperature crack resistance of asphalt mixtures

Summary

Introduction

The mechanical and physical properties of asphalt and its mixtures strongly depend on temperature variations. Some test results revealed that the direct addition of PCMs to an asphalt matrix can deteriorate the technological performance of modified asphalt [2,3,4] or modified asphalt mixtures [5,6,7,8], due to poor bonding between PCMs and the material matrix This problem has been mitigated by encapsulation of PCMs via some phase-change micro-capsulation technologies, namely the physical adsorption film coating [9,10,11,12], interfacial polymerization [13,14,15], and in-situ polymerization [16,17,18,19,20,21,22,23], minimizing the direct contact between PCM and asphalt. It is found that phase change microcapsules can improve the performance of asphalt [24], but the performance of the phase change modified asphalt mixture is reduced [20]

Methods

Results

Conclusion