Study On Electrothermal And Self-healing Characteristics Of Conductive Asphalt Mixture

Asphalt material has self-healing characteristics,which is due to the fact that asphalt is a kind of viscoelastic material with temperature and time dependence,which has the ability to flow or infiltrate cracks.However,the ability of asphalt to flow or infiltrate cracks in natural state is too small,so it is necessary to enhance the flow performance of asphalt in order to heal quickly.In this paper,conductive asphalt concrete is prepared by adding conductive phase material,and the flow of asphalt is accelerated by increasing the internal temperature of asphalt concrete,and the electrical,thermal and healing properties of conductive asphalt concrete are analyzed.This paper mainly studies the preparation of conductive asphalt concrete,conductive connection technology,electricity of conductive asphalt mixture and the distribution of temperature field around cracks.Finally,the healing characteristics of asphalt mixture are compared.First,the degree of fracture in the asphalt mixture mainly depends on the properties of the asphalt material,and the carbon fiber and the graphite are selected as the conductive phase material,and the rheological property of the carbon fiber graphite conductive asphalt cement slurry with different mixing amount can be researched.The results show that the temperature of the conductive asphalt slurry is higher than that of the crack in the process of power-on,so that the crack of the asphalt cement slurry can be rapidly healed,but the self-healing capacity of the paste will decrease with the increase of the mixing amount when the content of the carbon fiber and the graphite exceeds the critical point.By means of resistivity method,infrared thermal imaging method and digital image processing technology,the healing power level of the cement paste is defined,and the self-healing behavior of the asphalt cement slurry during the power-on heating process is evaluated.Secondly,through the experimental study of conductive asphalt slurry,the feasibility of the research method of self-healing characteristics of conductive asphalt concrete is determined.therefore,carbon fiber graphite conductive asphalt concrete was prepared.by measuring the resistivity and temperature-warming experiment of conductive asphalt concrete,the amount of conductive phase material was determined,and the sample with carbon fiber content of 0.5%+ graphite content of 10% was obtained to conduct electricity,and the heating performance was the best.Then,the electrified heating characteristics and mechanism of conductive asphalt concrete are discussed,the optimized electrified heating healing scheme is determined,the temperature field data around cracks of conductive asphalt mixture are measured by infrared thermal imager,and the temperature field cloud map around cracks is drawn by Matlab software.The three-point bending test of asphalt concrete beam was carried out,and the repeated healing ability of asphalt mixture was analyzed through the broken healing test of "fracture-healing-refracture".The results show that the healing recovery rate of the beam specimen decreases after repeated cracking,and repeated healing has a great influence on the healing performance.The cracks in conductive asphalt mortar and conductive asphalt concrete can heal rapidly,and the temperature at the crack has obvious temperature difference with the surrounding temperature,so the crack can be repaired directionally.Finally,the healing behavior characteristics of conductive asphalt concrete are summarized and analyzed,which lays a foundation for the further development of more effective application of electric heating healing technology in practice.