Research On Influence Of Snowmelt Agent To Performances Of Asphalt And Asphalt Mixture

The snow-ice disaster weather in winter can seriously influence the traffic safety on highway. A lot of snowmelt agent is applied to guarantee the traffic safety and unblocked as well as avoid serious economic loss, but the snowmelt agent can significantly cause performance attenuation of asphalt pavement. For this reason, according to the influence of snowmelt agent to pavement performances of asphalt and asphalt mixture, the thesis develops the research of laboratory tests by choosing 3 kinds of snowmelt agents such as NaCl, CaCl2 and NC.(1) The test results of abilities of dissolution, snow-melting and ice-melting for the 3 snowmelt agents under the different concentrations and temperatures show that the ice-melting effects of different snowmelt agents are very different. When snowmelt agents are used as solution form, the strong-weak ranking of the snow-melting ability is NaCl > NC > CaC12. When snowmelt agents are used as solid particle form, the strong-weak ranking of the ice-melting ability is CaC12 > NC > NaCl. Therefore, NC combines the advantages of NaCl and CaC12, and can quickly and steadily melt snow and ice.(2) The comparative analysis of pavement performances of base asphalt and SBS modified asphalt were performed before and after influence of snowmelt agent through the tests of penetration, low temperature ductility, softening point, Brookfield rotation viscosity, rotation film oven heating, DSC/TG, infrared spectrum analysis and so on. The results show that: after the influence of snowmelt agent, for base asphalt, its temperature susceptibility and high temperature properties are improved, and low temperature performance and aging resistance are decreased. Molecular structure of base asphalt does not change significantly. According to the degree of influence, the ranking is CaCl2 > NC > NaCl. For SBS modified asphalt, its temperature susceptibility, high-and-low temperature performances and aging resistance are all decreased, but the quality loss and thermal stability changed little, and the ranking of influence degree is NaCl > NC > CaCl2.(3) The basalt coarse aggregate which is soaked and freezed-thawed by snowmelt agents are adopt to perform the tests of Los Angeles abrasion value and aggregate crushing value as well as adhesiveness ability of asphalt and its mucilage with coarse aggregate. The results show: along with the soak time extending the anti-abrasion ability of coarse aggregate is reduced significantly, and the ranking of influence degree is NaCl > NC > CaCl2. The influence of snowmelt agents to the anti-crushing ability of coarse aggregate is little. The CaCl2 and NC cause that the adsorption ability of asphalt and its mucilage with coarse aggregate enhance. The NaCl cause that this ability reduces. The ranking of influence degree is CaCl2 > NC > NaCl.(4) Through the tests of freeze-thaw splitting, low temperature bending and high temperature rutting, the influence of snowmelt agents to asphalt mixture pavement performance was researched. The results show that: after the influence of snowmelt agents, all performance indexes of asphalt mixture such as freeze-thaw split ratio, flexural tensile strength and dynamic stability are decreased. Taking it all round, the ranking of influence degree is NaCl > NC > CaCl2.In summery, the influence of snowmelt agents to asphalt and asphalt mixture pavement performances is obvious, and the difference of the influence degree of different snowmelt agents is also obvious. Selecting properly the type of snowmelt agent, the category of modified asphalt, and controlling pavement porosity can increase resistant ability for the influence of snowmelt agents to asphalt pavement.