Low-temperature cracking is a major concern to improve the utilization of recycled asphalt mixture (RAM). A mechanism by which the crack propagates can provide a basis for advanced technological mitigation. Microcrack formations in the interfacial proximity of the virgin and aged binders have been identified from electron microscopy tests. Atomic force microscopy (AFM) experiment showed the trilayer phases at the virgin-aged binder interface. In this study, molecular dynamics (MD) simulations were conducted to understand the nanoscopic
crack propagation characteristics at the virgin-aged binder interface in the asphalt mixture with RAM. It was found that the blended binder of virgin and aged binders, and its interfaces with virgin and aged binders appeared to be the crack propagation zones. The relatively more significant matrix contraction of virgin binder and stiffer aged binder at a low temperature can cause more considerable tensile stress at the blended binder and its interfaces. Consequently, interfacial crack propagation became more profound and decreased the low temperature cracking resistance.@en

Sustainable and resilient pavement infrastructure is critical for current economic and environmental challenges. In the past 10 years, the pavement infrastructure strongly supports the rapid development of the global social economy. New theories, new methods, new technologies and new materials related to pavement engineering are emerging. Deterioration of pavement infrastructure is a typical multi-physics problem. Because of actual coupled behaviors of traffic and environmental conditions, predictions of pavement service life become more and more complicated and require a deep knowledge of pavement material analysis. In order to summarize the current and determine the future research of pavement engineering, Journal of Traffic and Transportation Engineering (English Edition) has launched a review paper on the topic of “New innovations in pavement materials and engineering: A review on pavement engineering research 2021”. Based on the joint-effort of 43 scholars from 24 well-known universities in highway engineering, this review paper systematically analyzes the research status and future development direction of 5 major fields of pavement engineering in the world. The content includes asphalt binder performance and modeling, mixture performance and modeling of pavement materials, multi-scale mechanics, green and sustainable pavement, and intelligent pavement. Overall, this review paper is able to provide references and insights for researchers and engineers in the field of pavement engineering.

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