Study On The Degree Of Carbon Fiber Dispersion In Carbon Fiber-Graphite Conductive Asphalt Mixes

As a conductive composite material,carbon fiber used rational not only can improve the conductive asphalt mixture electrical heating effect,but also provide good economic benefits to society.When carbon fiber is incorporated into conductive asphalt mixes,the dispersion of carbon fiber in the asphalt mix is not clear due to the mixing process and the material’s properties,which in turn affects its electrical conductivity and roadworthiness.In this paper,in order to improve the agglomeration phenomenon of carbon fibres in asphalt pavement applications,mechanical stirring observation test,mass weighing test,electrothermal test and microscopic test were used to obtain the carbon fibre distribution coefficient,carbon fibre dispersion coefficient and stress sensitivity coefficient by varying the parameters of carbon fibre content,dispersant concentration and mechanical stirring time,which were used as evaluation indexes for the degree of carbon fibre dispersion to arrive at the optimum dispersion conditions;also The rutting test,water immersion stability test,splitting test and small beam bending test were used to verify the roadworthiness,while the composition of the items was analysed by microscopic experiments of X-ray energy dispersive spectroscopy（EDS）,X-ray diffraction（XRD）and Fourier infrared spectroscopy（FTIR）.The main conclusions are as follows:（1）With the increase of carbon fiber content,dispersant concentration and mechanical stirring time,the carbon fiber dispersion effect showed a trend of increasing and then decreasing.The stress sensitivity coefficient and resistance distribution coefficient showed a decreasing trend and the carbon fiber dispersion coefficient increased with the increase of carbon fiber dispersion effect.（2）Under the single variable experiment,the average resistivity of GCAM reached the minimum when the carbon fibre doping was 0.3%,the dispersant concentration was 3～4 g·L^-1and the stirring time was extended to 8 min,26.22Ω·m,11.30Ω·m and 24.73Ω·m respectively;the stress sensitivity coefficient was the minimum,0.13,0.16 and 0.28respectively;the distribution coefficient of carbon fibre was the best,0.83,0.81 and 0.92respectively.The carbon fibre distribution coefficients were 0.83,0.81 and 0.92 respectively,when the carbon fibre dispersion effect was the best.（3）The optimum dispersion conditions of GCAM are:carbon fiber content at 0.31%,mixing time at 6.32 minutes,dispersant concentration at 3.94g·L^-1.The GCAM resistance after optimized dispersion of carbon fiber varied little under the influence of load,and there was consistency in the warming trend of the same group of GCAM specimens.SEM analysis results show that the optimally dispersed carbon fibers can be in a uniformly dispersed lap state in the asphalt mixture.（4）The high-temperature stability and low-temperature crack resistance of GCAM are improved after the optimization of carbon fiber dispersion.The water stability decreases and it sresidual stability decreases to 83.47%and freeze-thaw splitting strength decreases to 4123N·m^-2,which meets the specification requirements.And by EDS,XRD,FTIR analysis of GCAM after the addition of HEC dispersant,the content of element O in GCAM specimens increased significantly,and the content of element C increased slightly,and did not generate new phases,HEC dispersant has no significant effect on GCAM.