Study On The Mechanism And Decay Law Of Anti-icing Of Salt-storaged Composite Fiber Modified Asphalt Mixture

The existing anti-icing additives for snow on asphalt pavement in cold areas have high prices,and have limited improvement on the technical performance of the mixture,especially the huge impact on the ecological environment,which hinders its large-scale popularization and application.Therefore,this paper develops salt-storaged composite fiber anti-icing agent with appropriate price,good effect and environmental protection,which is suitable for asphalt pavement,and systematically discusses and studies its related problems in application.The preparation technology of salt-storaged composite fiber was studied,and the blending proportion of anti-icing materials and fiber in salt-storaged composite fiber were determined.That is,organic resin: sodium acetate: sodium silicate: lignin fiber: sepiolite fiber = 1:1.336:0.573:0.17:0.255.Through asphalt slurry test,salt-storaged composite fiber can improve the high-temperature and low-temperature rheological properties of SBS modified asphalt,and has high conductivity and anti freezing characteristics.Through the performance test of asphalt mixture,the road performance of asphalt mixture with different content of salt-storaged composite fiber after equal volume replacement of mineral powder by salt-storaged composite fiber under four gradations is analyzed.The results show that compared with MFL asphalt mixture,the salt-storaged composite fiber asphalt mixture has better high-temperature shear resistance,lowtemperature crack resistance,water stability,and anti-fatigue performance,but its skid resistance is reduced.With the increase of the content of salt-storaged composite fiber,the performance improvement range of the modified asphalt mixture gradually becomes lower,and the anti-skid performance decreases more.Consequently,it is fully feasible to use a certain amount of salt-storaged composite fiber in asphalt mixture.Through the study on the micro morphology of salt-storaged composite fiber and its modified asphalt,the salt crystal is evenly distributed in the composite fiber,that is,the salt-storaged composite fiber has good salt absorption characteristics,and the organic resin on the surface can strengthen the bonding between salt-storaged composite fiber and asphalt.After SBS modified asphalt is mixed with salt-storaged composite fiber,the dispersion degree of SBS polymer is more significant,and the salt-storaged composite fiber,SBS and asphalt form an interactive connection,which greatly enhances the structural stability.The-COOH group in the salt-storaged composite fiber has a chemical reaction with asphalt,which changes the carbon chain structure of asphalt,and increases the composition of macromolecule chemicals in asphalt,which makes the aging resistance and the thermal stability of the modified asphalt modified by salt-storaged composite fiber significantly improved.For the anti freezing asphalt mixture,with the action of rain,ice and snow,the precipitation of salt in the pavement is accelerated,and the anti freezing ability is easy to decay too fast under load.The anti icing performance and void characteristics of saltstoraged composite fiber asphalt mixture before and after different hydrodynamic scouring time were studied by ice setting adhesion test and CT test.The addition of saltstoraged composite fiber has little effect on the void structure of the mixture.Under the action of dynamic water,the solution conductivity of salt-storaged composite fiber asphalt mixture continues to increase,the maximum torque increase rate becomes slower,and its anti icing performance decays more slowly,and the average void volume and the most probable void gradually increase,and the void dimension gradually decreases.However,with the continuous increase of the content of salt-storaged composite fiber,the change range of void characteristic index becomes smaller and smaller,show that with the analysis of salt,the fiber can well absorb asphalt,divide the voids in the mixture,increase the number of micropores,and ensure the stability of void structure,and ensures longterm anti freezing performance.It is proposed that the ice binding force torque value of anti ice pavement mixture should not more than 60N·m,and the anti ice decay characteristics of salt-storaged composite fiber asphalt mixture is analyzed.In winter,the water in the voids of asphalt pavement will produce salt freeze-thaw cycle under the change of external temperature,resulting in the damage of asphalt pavement.The durability of salt-storaged composite fiber asphalt mixture before and after salt freeze-thaw cycle is studied by OT test and four point bending fatigue test.With the action of salt freeze-thaw cycle,the salt in anti freezing asphalt mixture slowly precipitates,and it is evenly dispersed in the water in the gap,which reduces the frost heaving force when the water freezes.In particular,due to the precipitation of sodium silicate in the salt-storaged composite fiber,and the surface energy of the mixture is reduced,so that the water is easier to fall off when it freezes,and the reinforcement of the fiber can improve its anti cracking ability.Adding salt-storaged composite fiber can significantly improve the durability of asphalt mixture before and after salt freeze-thaw cycle.The fatigue degradation characteristics of salt-storaged composite fiber asphalt mixture is analyzed.