Research On Conductive Asphalt Concrete With PAN-based Carbon Fiber

The extreme weather, such as freezing rain and snow and so on, can not only bring a serious hidden dangers to the traffic safety and driving comfort but also cause various kinds of road damage. How to melt ice on pavements and improve synthetically pavement performances will become the current research hotspot. According to the principles of composite materials, by mixing short chopped PAN-based carbon fibers within asphalt mixtures, the performances of asphalt mixtures, such as high temperature stability, low temperature stability, water stability, electrical conductivity and others, will improve with the fiber advantages of low resistivity, high strength and so on. Then the thesis provides the technical support for engineering applications in electrical conductivity, ice-melting and smart repair for pavements.(1) Through the research on the relationship between carbon fiber length and dispersion and the preparation method of samples, it was found that the carbon fiber of 9mm length dispersed best, and the effect of mixing specimen method for asphalt mixtures with mixing carbon fiber after joining the asphalt is better. Through the research on asphalt mixture proportions with different carbon fiber contents, it was found that the best asphalt-aggregate ratio, flow values, clearance rate, saturation are increasing with the increase of carbon fiber content to reflect the effects of stability, adsorption and increasing viscosity for carbon fiber to asphalt. However, the extra carbon fiber at the higher carbon fiber contents will collect as conglobation to produce the effects of expansion and lag, and cause the very big void content for the asphalt mixtures.(2) According to the theories of conductive path, tunnel effect, field emission and conductive percolation, the conductive mechanism of carbon fiber was analyzed in the conductive asphalt mixture, and the formation process of conductive network was revealed. The resistivity of PAN-based carbon fiber asphalt concrete decreases continuously with the carbon fiber content increasing. The mixing content range with resulting in electrical conductivity percolation threshold is as 0.032%~0.1%. When controlling with the electrical resistivity of 100? ? m, the average content of carbon fiber is as 0.058% for the asphalt mixtures with different asphalt-aggregate ratios, and the value can be regarded as the minimum mixing content of carbon fiber.(3) The test results of freeze-thaw splitting, soaking Marshall, rutting and trabecular bending showed that the pavement performances of carbon fiber asphalt mixtures, such as water stability, high temperature stability and low temperature cracking resistance, are obviously improved than the ordinary asphalt mixtures to meet the needs of pavement performances in specifications. From the modification effects, the suitable content range of carbon fiber for the carbon fiber reinforced asphalt mixture is as (0%, 0.76%] to meet the pavement performances, and 0.1% is regarded as the best content.The results of pavement performances for the PAN-based carbon fiber asphalt mixture were synthesized to obtain a reasonable range of [0.058%, 0.76%] for carbon fiber content, and the best content is as 0.1%. The technical and economic feasibility analysis show that the content of 0.1% PAN-based carbon fiber conductive asphalt concrete is stable in resistivity and well in pavement performances to meet the requirements of traffic, snow-melting and ice-melting. So the mixture has good social and economic benefits, and can be applied in asphalt pavements.