Effect of chemical composition and structure of asphalt binders on self-healing

Abstract

Asphalt binders have the self-healing ability to repair fatigue cracking automatically, and therefore the fatigue life can be extended. The extended fatigue life depends on the coupling effect between the chemical kinetics of asphalt molecules at cracking surfaces and the rate of the crack growth under fatigue loading. Obviously, the chemical characteristics of asphalt determine its inherent self-healing ability. However, uncertainty still remains in the effect of the chemical composition and structure of asphalt on the inherent self-healing ability. In this paper, four different Pen grade asphalt binders were characterized by Thin Layer Chromatography (TLC), Gel Permeation Chromatography (GPC), Fourier Transform infrared spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR), and the self-healing abilities of asphalt binders were investigated by a fatigue-rest-fatigue test with DSR. It was found that asphalt with a higher small molecule content/large molecular content ratio combined with higher aromatics content has a greater self-healing ability. In addition to the chemical composition of asphalt, its molecule structure also plays an important role in determining its self-healing ability. A higher I1460/I1376, S/Ar ratio and Har value, indicating a lower branched-chain and higher long and thin molecule content in asphalt, could promote self-healing. Based on Grey relational analysis, the microstructure of asphalt has a greater impact on the self-healing ability of asphalt binder compared with other factors.