Preparation And Properties Of Self-deicing Coating Based On Layered Double Hydroxide

In winter,the snow and ice on the asphalt pavement not only lead to traffic accidents,but also greatly reduce the efficiency of road transport.More snow-melting materials and technologies have been developed to solve this problem around the world.Self-deicing coating has got more and more applications,because it can be easily sprayed on asphalt pavement and it has high efficiency of melting ice.However,chloride salts are used in most self-deicing coating,it will gradually release under the rain and vehicle load.These released salts not only damage the environment,but also shorten the life of self-deicing coating.It is essential to develop new melting agents which does not damage the environment as well as melts ice or snow sustainably,then the new melting agents can be applicated to prepare new self-deicing coating to solve the problem from ice and snow.In this paper,layered double hydroxide containing chloride(Cl~-LDHs)was obtained by calcination recovery method,freezing point and carbon steel corrosion rate of Cl~-LDHs solution were tested.Self-deicing coating was prepared by blending Cl~-LDHs and asphalt emulsion.Deicing performance of the self-deicing coating was investigated by testing the melting ice point of coating surface and the adhesion force between ice and self-deicing coating,then deicing durability were evaluated by immersion test and microscopic observation.The effect of waterborne epoxy resin,SBR latex and Cl~-LDHs on coating's physical properties was investigated.Finally,the effect of self-deicing coating on pavement performance was studied by testing the permeability coefficient,friction coefficient and structure depth.The main conclusions were as follows:(1)Cl~-LDHs prepared by calcination recovery method can lead the decreasing of freezing point,and it has little corrosion.Freezing point of solution with 20wt%Cl~-LDHs was-9.1?.The corrosion rate of carbon steel in 20wt%Cl~-LDHs solution was only 0.12mm/a.(2)Self-deicing coating prepared by blending Cl~-LDHs and asphalt emulsion could reduce the melting ice point on the coating surface and the adhesion force between ice and self-deicing coating.When the amount of the self-deicing coating with 8wt%Cl~-LDHs was 400 g/m~2,the melting ice point on the coating surface was-3.9?and the adhesion force between ice and self-deicing coating was 26N at-15?.Self-deicing coating can melt ice and snow when the temperature was-5~-2?.(3)There was no effect on the deicing performance after immersion in water,conductivities of the immersion liquids were constant which indicates that Cl~-LDHs in the self-deicing coating wasn't dissolved.And microstructure of the self-deicing coating almost unchanged,immersion had little effect on Cl~-LDHs.(4)Waterborne epoxy resin and SBR latex could enhance the adhesion strength obviously,and the penetration was decreased,the softening point and extension were increased after mixing with waterborne epoxy resin and SBR latex at the same time.While Cl~-LDHs had little effect on adhesion strength between self-deicing coating and pavement,but Cl~-LDHs could increase the softening point,and decrease the penetration as well as the extension.(5)The new asphalt mixture specimen has better performance,the permeability coefficient of asphalt pavement was decreased after coating,the impermeability was improved further.The friction coefficient and structure depth were reduced,but it could achieve the standard when the amount of the self-deicing coating was under500 g/m~2.The performance of old asphalt pavement was poor,the permeability coefficient was decreased obviously after spraying self-deicing coating,at the same time the friction coefficient and structure depth were decreased little.