Research On Influence Of Chloride Deicing Salt’s Concentration On Performances Of Asphalt And Asphalt Mixture

In winter,snow and ice on the asphalt road often appears in northern area of China,which affecting road safety seriously,in order to avoid major traffic accidents,ensure smooth traffic and safety,spraying of chloride deicing salt is often used to alleviate traffic pressure,while chloride deicing salt is deicing and melting snow it will do damage to the road performance of asphalt pavement.The extensive spraying of snowmelt agent in a mechanical way will cause uneven distribution,the road performance of the pavement was significantly decreased after eroded by snowmelt agent of high concentration.In this paper,for the influence of chloride deicing salt’s concentration on performances of asphalt and asphalt mixture,using water and sodium chloride solution of four kinds of concentration which are respectively 7%、14%、21%、28% to do indoor test and give a suggested concentration for actual snow removing.(1)The result of the deicing and snow melting test with different concentrations of chloride salt solution shows that: at-10℃,the chloride salt solution ability of deicing and snow melting increased and then decreased with the increase of chloride salt’s concentration,and it became strongest when the concentration of chloride salt solution was 23%.(2)Take matrix asphalt affected by chloride deicing salt of different concentrations as the research object,the test of asphalt’s three indexes,the Brookfield viscosity test,adhesion test of asphalt to aggregate and the infrared spectrum test were done.The results of the tests show that with the increase of chloride deicing salt’s concentration,the temperature susceptibility and elevated temperature property of asphalt are getting better and better,the low temperature property and adhesion to aggregate are getting worse,the content of saturated hydrocarbon in asphalt is getting less and less,the chemical reaction between asphalt and chloride deicing salt did not produce new functional group.In the 10 ℃extension test of asphalt,the ductility of the matrix asphalt after the immersion of the chloride salt solution with a concentration of more than 14% can not meet the requirements of the specification.(3)Take asphalt mixture which had been immersed in chloride deicing salt of different concentrations as the research object,low temperature splitting test,uniaxial static compression creep test and freeze-thaw splitting test were done,and I used viscoelasticity theory to analyse creep test of asphalt mixture.The test results show that with the increase of the concentration of chloride deicing salt,the asphalt mixture’s elevated temperature property,low temperature property and water stability are getting worse and worse.In the freeze-thaw splitting test of asphalt mixture,the tensile splitting ratio(TSR)of asphalt mixture which had been immersed in chloride salt solution with a concentration of more than 14% can not meet the specification requirements.To sum up,the concentration of chloride deicing salt has a significant impact on the performance of asphalt and asphalt mixture.In the actual snow removing,the spraying amount of snowmelt agent should be controlled according to the amount of snowfall and road icing situation,paying attention to spray evenly to ensure that the concentration of chloride deicing salt sprayed on the pavement is not more than 195.35 g per unit area,which can effectively reduce the harm caused by snowmelt agent.