Research On Anti Freezing Technology Of Asphalt Concrete Bridge Deck

The ice and snow weather in winter is an important cause of traffic accidents.In cooling,the cooling rate of bridge deck pavement is faster than that of pavement,which leads to the formation of ice condensation time of bridge deck pavement earlier than that of pavement.The ice on the bridge deck makes the friction loss of the bridge deck,which leads to the great decline of the anti sliding ability of the bridge deck,and seriously affects the controllability and safety of vehicles.This paper attempts to combine the low thermal conductivity material and the salt storage material into the asphalt mixture to form a kind of low thermal conductivity salt storage asphalt mixture,which is used to prevent the ice disaster of the bridge deck.The main research contents and conclusions of this paper are as follows:(1)Temperature field analysis of asphalt concrete deck pavement structure.The temperature field of asphalt concrete bridge deck pavement is established by using ABAQUS finite element software,and the influence of wind speed,daily solar radiation and heat conductivity on the temperature field of bridge deck pavement is analyzed.Then,the change difference of temperature field of bridge deck pavement,low heat conduction bridge deck pavement and pavement pavement structure is analyzed under the condition of cooling.The research shows that when the wind speed is 2.6m/s and 12.6m/s,the maximum temperature difference of the bridge deck pavement structure in one day is 1.1℃,the maximum temperature difference of the bridge deck pavement structure in one day is 5 ℃ when the daily illumination is8.06mj/m2 and 1.06mj/m2,and the maximum temperature difference of the bridge deck pavement structure in one day is 1.2℃when the thermal conductivity is 6680j/m·h·℃and 2680j/m·h·℃.Under the cooling condition,the maximum temperature difference between the bridge deck pavement and the pavement is about 2 ℃,and reaches the maximum value in the second hour of cooling,and the maximum temperature difference between the low heat conduction bridge deck pavement and the pavement is 1.4℃,but in the second hour of cooling,the temperature difference between the bridge deck pavement and the pavement is only 0.3℃,and reaches the maximum temperature difference in the sixth hour of cooling.The low heat conduction bridge deck pavement can effectively heat preservation 2 hours before the beginning of cooling and delay the formation of bridge deck ice.(2)Mix proportion design and road performance research of low heat conduction salt storage bridge deck pavement mixture.On the basis of the best gradation of SMA-13 mixture,the equal volume replacement method was used to replace the aggregate with 4.75-9.5mm ceramic waste,and the mineral powder was replaced with MFL.Marshall experiment,rutting experiment,small beam bending experiment,Marshall stability experiment and freeze-thaw splitting experiment were carried out to study the influence of the two materials on Marshall experiment results and mixture road performance.The results show that with the increase of the content of ceramic and MFL,the density,stability and road performance of the mixture decrease,while the flow value,mineral clearance rate and saturation have no obvious regularity.When the ceramic content is 40% and MFL content is 60%,the maximum theoretical density of the mixture is reduced by 0.183g/cm3,Marshall stability is reduced by 25%,dynamic stability is reduced by 27.8%,the maximum bending tensile strain is reduced by 13.6% and residual stability is reduced by 2.9%,but the above properties meet the specification requirements.In this paper,it is determined that the ceramic content of the mixture for low thermal conductivity salt storage bridge pavement should be 40%,MFL content is appropriate It should be 60%.(3)Study on the anti freezing effect of low heat conduction salt storage bridge surface.The thermal conductivity of the asphalt mixture with low thermal conductivity and salt storage is measured by the steady-state plate method.The ice melting experiment is used to study the ice melting effect of the mixture with low thermal conductivity and salt storage.The sodium chloride dissolution experiment is used to study the relationship between the concentration of sodium chloride and the conductivity.The influence of void ratio and temperature on the rate of sodium chloride evolution is studied.The prediction model is established to calculate the effective use of the bridge deck pavement with low thermal conductivity and salt storage Years.The results show that the thermal conductivity of the mixture is2473j/m·h·℃,which is 52.8% of that of SMA-13.When the content of MFL is 60%,the mass loss of ice is 83.1% at the 25 th minute of melting.The higher the porosity and temperature,the faster the precipitation rate of sodium chloride.According to the prediction model,the effective service life of ice melting for the bridge deck pavement with low thermal conductivity and salt storage is 5.7 years.(4)The working principle of the bridge deck ice early warning system is to collect the multiple key parameters of the road with high precision and analyze the parameters in time domain and frequency domain,so as to realize the accurate identification of the bridge deck ice state.Its main functions include collecting data,pavement temperature,bridge deck temperature data transmission analysis,ice freezing early warning and forecast,daily report: output working status and early warning report in the unit of year,month and week.The warning system can accurately predict the temperature of the bridge deck with a maximum error of 0.4℃.