Daquan Sun

Electrical characteristics of conductive ultrathin bonded wearing course for active deicing and snow melting

ABSTRACT Active deicing and snow melting technologies, such as conductive asphalt concrete and heating cable, have got extensively concerned, however they are not applicable to the existing roads. Therefore, the conductive ultrathin bonded wearing course (CUBWC) is proposed, which mainly consists of the conductive functional layer (CFL) and gravel wearing course. The CFL is prepared by blending the graphite, carbon fibre (CF) and epoxy resin adhesive. To get the optimal electrical characteristics of CUBWC, the effects of CF length, CF content and graphite content on the resistivity of CFL were measured. The temperature sensitivity test and the temperature cycling test were further conducted to evaluate the temperature sensitive property and stability of CUBWC. Finally, the optimal contents of the graphite (25% by mass) and CF (4% by mass) were determined by considering the effective electrical conductivity and temperature stability of CUBWC.

A comprehensive review on self-healing of asphalt materials: Mechanism, model, characterization and enhancement

Self-healing has great potential to extend the service life of asphalt pavement, and this capability has been regarded as an important strategy when designing a sustainable infrastructure. This review presents a comprehensive summary of the state-of-the-art investigations concerning the self-healing mechanism, model, characterization and enhancement, ranging from asphalt to asphalt pavement. Firstly, the self-healing phenomenon as a general concept in asphalt materials is analyzed including its definition and the differences among self-healing and some viscoelastic responses. Additionally, the development of self-healing in asphalt pavement design is introduced. Next, four kinds of possible self-healing mechanism and corresponding models are presented. It is pointed out that the continuum thermodynamic model, considering the whole process from damage initiation to healing recovery, can be a promising study field. Further, a set of self-healing multiscale characterization methods from microscale to macroscale as well as computational simulation scale, are summed up. Thereinto, the computational simulation shows great potential in simulating the self-healing behavior of asphalt materials from mechanical and molecular level. Moreover, the factors influencing self-healing capability are discussed, but the action mechanisms of some factors remain unclear and need to be investigated. Finally, two extrinsic self-healing technologies, induction heating and capsule healing, are recommended as preventive maintenance applications in asphalt pavement. In future, more effective energy-based healing systems or novel material-based healing systems are expected to be developed towards designing sustainable long-life asphalt pavement.