Preparation And Snow Melting Behavior Of Graphene Multiphase Conductive Concrete In Severe Cold Environment

China has a vast territory,and cold regions account for about 40% of the total land area.However,more than half of the cold regions have serious problems of road snow and ice in winter,which brings great inconvenience to people’s daily travel in this area.The conductive concrete with green environmental protection,energy saving and high efficiency,without interrupting traffic,it is one of the effective ways to solve the problem of road ice and snow in cold area.In this paper,a new nano material graphene was used to prepare graphene multiphase conductive concrete.Based on the requirements of road snow melting and deicing on the road use and electric heating performance of concrete,the mechanical and electrical properties of concrete with different amount of graphene were studied.Through the optimization of electrode spacing and input voltage,the snow melting efficiency and energy consumption of graphene multiphase conductive concrete are improved.The performance improvement and evaluation of conductive concrete for snow melting in severe cold environment provide a theoretical basis,based on the research results.The promotion and application of graphene multiphase conductive concrete in road snow melting engineering has been actively promoted.The specific research contents are as follows:(1)In this experiment,the conductive phase of graphene multiphase conductive concrete is composed of in-situ multilayer graphene(ISMG),carbon fiber(CF) and steel fiber(SF) by physical method.In order to achieve the target strength of conductive concrete for snow melting in severe cold environment.The compressive strength and flexural strength of concrete at 28 days of age were tested,when ISMG content was 0%,0.2%,0.4%,0.6%,0.8%and 1.0%.The results show that when the content of ISMG is 0.4%,the compressive strength and flexural strength of concrete at 28 d are 45.0 MPa and 5.7 MPa respectively.Scanning electron microscope(SEM)was used to analyze the micro morphology of the interface transition zone of graphene multiphase conductive concrete.It is proved that ISMG can improve the compressive strength of concrete by strengthening the compactness and the flexural strength by strengthening the toughness.(2)In order to achieve the designed resistivity,sodium dodecylbenzene sulfonate was used as graphene dispersant by orthogonal test of dispersant,and the dosage of dispersant was twice the mass of ISMG;by comparing the resistivity test results of multimeter and 108 V AC,it is concluded that the resistivity test results of concrete using 108 V AC are more accurate and reliable;by testing the resistivity of concrete at28 d,56 d,90 d,180 d and 360 d when ISMG content is 0%,0.2%,0.4%,0.6%,0.8%and 1.0%;it is found that the best resistivity of concrete at 28d is 12.66?·m,when ISMG content is 0.4%;and the long-term resistivity of concrete is relatively stable.Through SEM,it is found that ISMG can form a three-phase composite conductive system with carbon fiber and steel fiber to improve the conductivity of concrete.(3)The snow melting process of conductive concrete is analyzed by the law of conservation of energy and the theory of thermodynamics.The effective ways to improve the snow melting efficiency of conductive concrete and save the energy consumption of snow melting are proposed:optimizing the resistance,increasing the thermal conductivity of concrete,applying insulation layer,and appropriately reducing the thickness of concrete plate.The thermal conductivity of concrete with ISMG content of0%,0.2%,0.4%,0.6%,0.8% and 1.0%at 28 days was tested.It was found that the thermal conductivity of conductive concrete increased gradually with the increase of graphene content.When the content of graphene was 1.0%,the thermal conductivity of conductive concrete was 3.7 w/(m·K).(4)The indoor snow melting experiment was carried out,and the severe cold environment was simulated by freezer.The effects of electrode spacing of 10 cm,18 cm,28 cm and input voltage of 108 V,156 V,220 V on snow melting efficiency and energy consumption of concrete were studied.The optimal electrode spacing is 10 cm and the optimal input voltage is 156 V.The results show that the optimized graphene composite conductive concrete slab can melt 21 cm thick snow in 2 hours,and the average energy consumption density is 6.6 k W·h/m~2,when the initial ambient temperature is -15℃,the wind speed is 20 km/h,the thickness of the slab is 5 cm,the electrode spacing is 10 cm,and the input voltage is 156 V.