Conductivity And Compression Sensitivity Of Epoxy Resin Modified Carbon Fiber Reinforced Cement Composites

Carbon fiber cement-based composite material not only has great mechanical properties,but also has great electrical conductivity,pressure sensitivity,thermal sensitivity and electromagnetic shielding.Carbon fiber cement-based composite material is widely used in internal damage monitoring of structural facilities such as traffic,roads,concrete engineering,deformation self-adjustment of bridge structure,snow melting in northern winter and industrial anti-static.However,the sensitivity of conductivity and pressure sensitivity is attenuated faster with the increase of age,which greatly hinders the engineering application of carbon fiber cement-based composites.In this paper,a resin cement matrix is prepared by adding an appropriate amount of epoxy resin to the cement-based material firstly,then the epoxy resin modified carbon fiber reinforced cement composites(RMCFRC)is prepared by incorporating the chopped carbon fiber into the resin cement matrix.After that,the influence of resin incorporation on RMCFRC conductivity and electrical conductivity was studied.The effect of resin content on RMCFRC conductivity and its conduction mechanism were analyzed by AC impedance spectroscopy.In addition,the effect of epoxy resin on the mechanical properties and flexural toughness of RMCFRC was investigated.Furthermore,the influence of resin incorporation on the rate of change of electrical resistance of conductive composites under stress was studied,and the influence of RMCFRC pressure sensitivity under monotonic and cyclic loading was established.The main conclusions are drawn as following:(1)In order to obtain the best conductivity and conductive stability,the ratio of the diluent ethyl acetate to the polymer epoxy resin should not be too large or too small,its ration should be controller 0.5,the composite has the best electrical conductivity.(2)Proper incorporation of resin and carbon fiber can improve the electrical conductivity of RMCFRC,has no adverse effect on the strength development.However,the incorporation of resin and carbon fiber should not be too large,it should be controlled within 8% and 0.4%;in this range,the resistivity of RMCFRC decreases with the increase of resin and carbon fiber content.At same time,the water-cement ratio has a great influence on the conductivity of RMCFRC.When the water-cement ratio is 0.3,the composite has the best electrical conductivity.(3)Continues to analyze the AC impedance spectrum of RMCFRC under different carbon fiber and resin content.It was verified that the percolation threshold was reached when the carbon fiber content was 0.4%.At the same time,the impedance curve of the composite gradually shifts to the left as the resin content increases.When the resin content exceeds 8%,the impedance curve will shift to the right as the resin content increases.(4)Finally,through the stress-resistance relationship test,it is proved: RMCFRC has good pressure-sensitive properties.When a monotonic load is applied,the rate of change of resistance increases first and then decreases with the increase of the amount of resin.When the resin content is 8% and the carbon fiber content is 0.4%,the RMCFRC has the highest rate of change in resistance and the best pressure sensitivity.When a low stress cyclic load is applied,the incorporation of the resin can significantly improve the pressure sensitive stability of the composite.The resistivity of the resin-doped composite material is almost stable after each loading and unloading.