Preparation And Properties Of Thermosensitive Autocrine Microcapsules Based On Asphalt Pavement Deicing

Bitumen is one of the most widely used pavement materials in road construction.As an adhesive,bitumen improves the ability of mineral materials to resist pavement damage,and has the advantages of low vibration,low noise and wear resistance.Due to the low temperature in winter,the snow on the road surface is frozen due to snowfall.The combination of ice and pavement greatly reduces the adhesion coefficient of the road,which has a serious adverse impact on the stability and traffic safety of the road.The traditional passive deicing method has some disadvantages,such as low efficiency,road surface damage and serious pollution.The new method of active snow and ice removal can effectively remove the ice and snow on the road surface by improving the performance of the material itself.In the previous research,active deicing pavement has the problems of poor durability and aging.How to achieve long-term intelligent deicing without reducing pavement performance has become the current research hotspot.Inspired by the bionic anti ice structure of bird feather autocrine oil,a kind of intelligent deicing bitumen material with long-term deicing function was synthesized based on the controlled release microcapsules with temperature response characteristics.The autocrine microcapsules were prepared by in-situ polymerization.The wall of the autocrine microcapsules was composed of PVA/HMMM as the wall and glycerin with deicing effect as the core material.The preparation technology,physical and chemical properties,mechanical properties and deicing performance of microcapsule/bitumen were systematically studied.The surface morphology of the microcapsules was analyzed by SEM,and the structure of the microcapsule composite shell was discussed.The results showed that the polymer interpenetrating polymer network was formed on the wall of the microcapsule,and the PVA gel was used as the "gate" of the microcapsule to be embedded on the HMMM skeleton to regulate the release of the core material.The yield stress of a single microcapsule was tested by nanoindentation technology.The yield stress of 1 % PVA microcapsule was 1.59 MPa.With the increase of PVA in wall material,the yield stress of microcapsule decreased.When the content of PVA reached 5 %,the yield stress of microcapsule was 1.125 MPa,which could still keep intact during the bitumen processing.ATR-FTIR confirmed that the microencapsulated bitumen had the characteristics of temperature response,and the rate of autocrine increased with the decrease of temperature.With the increase of PVA content in the composite shell,the secretion rate of microcapsules increased.When the content of PVA in the shell reached 5 %,the autocrine rate of microcapsules reached the threshold.The ice resistance of bitumen samples was evaluated by analyzing the ice shear force.Compared with pure bitumen,the ice shear force of microcapsule/bitumen composite is significantly reduced,and the ice shear force of 5 % PVA microcapsule/bitumen composite is only 18 % of that of pure bitumen,which proves the deicing ability of the composite.This kind of autocrine microcapsule/bitumen composite may be widely used in long-term pavement deicing.