Research On Mechanic-electric Response Of Conductive Asphalt Concrete

Asphalt concrete has been widely used in various expressways all over the world. The service life of asphalt pavement can be prolonged by effective maintenance.At present,the quality evaluation of asphalt pavement is studied by visual observation and evaluatation of experts,which are experiential and unreasonable.The self-monitor property of conductive asphalt concrete makes it possible to verdict the inner failure without damaging the pavement and to know the healthy state of asphalt pavement,so as to provide a scientific guide to the maintenance of asphalt pavement.The research of self-monitor property of conductive asphalt concrete has great importance to the damage examination,monitor of road traffic and load, Intelligentized management of road transportation.The conductive mechanics and the factors affecting the resistance of conductive asphalt concrete(CAC)were studied in this paper.The conductive mechanics can be explained by tunnel effect and percolation theory.Effects of stress,temperature,air void and damage on the resistivity of conductive asphalt concrete are investigated in this paper.Superpave 12.5 mixture type was chosen in this paper,Asphalt mixture with good electrical and road relative properties was obtained by the adding of flake graphite.The Indirect Tensile Test,Uniaxial Compressive Test,three-point Bending Test and Direct Tensile Test were conducted in this paper,while circle fatigue mode and static loading mode were analyzed over a range of temperatures.The result for the variation of resistivity was analyzed by combining the stress analysis and the temperature change.Results indicated that the variation of resistivity was differently from the various test modes,the resistance of conductive asphalt concrete material shows reasonably sensitive to the stress and strain.Under the mode of static loading,the resistance of conductive asphalt concrete will increase with the stress increase at the beginning of the test,and then decrease,and finally increase gradually when the specimen is close to fracture state under a certain level of stress.Results of the fatigue test show three periods of the conductive asphalt concrete resistance during this mode:rapid decrease phase,smooth stretch phase and rapid increase phase.The resistance changes on the three phases show the inner structure transformations of the specimen.The resistance exhibits quasi-elasticity deformation at low temperature and quasi-plasticity deformation at high temperature.Thus the regulation of variation of resistance show obvious distinctions at different temperatures.The resistance curve shows smooth property at low temperature compared with that at high temperature.The resistance regression equations of CAC fatigue test are established,which can be used to characterize the resistivity variations of the conductive asphalt concrete during fatigue tests and provided the theoretical foundation of self-monitor.