| Road heat-reflective coating can effectively alleviate the heat stability of road and the urban heat island effect in the summer.However,there is environmental pollution in the preparation and construction process.In order to solve the problem,this paper will develop a high reflectivity,good pavement performance,green and environmentally friendly waterborne epoxy heat-reflective coating.The material was coated on asphalt pavement in the summer can effectively reduce the temperature of the road surface,thereby reducing the thermal stability of pavement diseases and alleviating the urban heat island effect.Epoxy resin E51,OP-10/SDS complex emulsifier,Span-80/SDS complex emulsifier and homemade binary multi-block polymer emulsifier were used as raw materials to prepare the waterborne epoxy emulsions.The influencing factors in emulsification process of epoxy resin were studied by the single factor test.Considering the properties of the emulsion and the preparation process in the selection of self-made emulsifier conditions,when the emulsifier dosage of 23%,emulsifying temperature of 60?,shear rate of 3500n/min,drip rate of 2mL/min and emulsifying time of 30 min,the obtained emulsion had smaller particle size and better stability.The waterborne epoxy curing agent BH-560 was selected,that its curing time and curing temperature met the construction requirements,when its dosage was 45%,the film-forming had better performance.Its adhesion and hardness was 1 and 5H.The water absorption was small and the thermal stability was good.Waterborne epoxy emulsion was selected as film-forming material and rutile TiO2,precipitated SiO2 and hollow microspheres as main functional filler to prepare heat-reflective coating.The coating formulation was optimized by orthogonal test: 100 g waterborne epoxy emulsion of 40% solids,7g TiO2,2.5g SiO2 and 2g hollow microspheres.A series of heat reflective coatings with various colors can be prepared by adding colored pigments.The dosage of 2% was suitable,and the cooling effect of the light reflecting coatings was better than that of the dark ones.The other performance of heat-reflective coating were tested and it was found that the coating had good water resistance and solvent resistance.The cooling effect of waterborne epoxy heat-reflective coating was tested by indoor simulated solar radiation device.The results showed that the optimum coating dosage was 0.9kg/m21.0kg/m2 in the application of AC asphalt mixture,and the temperature of the specimen was higher,the cooling effect of the coating was better.When temperature was 60?,the maximum cooling value can reach 10.5?.The results showed that when the outdoor temperature was 34?35?,the coating can reduce the temperature of the specimen by 7.6?.The cooling effect of the coating pavement surface was tested,and the maximum cooling value can reach 8.4?,which proved that the waterborne epoxy heat-reflective coating had better cooling effect.The anti-sliding performance of waterborne epoxy heat-reflective coating was evaluated by pendulum friction tester.The results showed that the coating would reduce the anti-sliding performance of pavement.On the one hand,the addition of 0.8kg/m2 quartz sand by stratifying could significantly improve its anti-sliding performance to meet the requirements of driving safety.On the other hand,it had a little effect on the coating cooling.Other results showed that the coating had good adhesion performance,wear resistance and temperature resistance,which could be effectively applied to asphalt pavement.It would play the role of sealing water,thereby effectively reducing road water damage.Waterborne epoxy heat-reflective coating has good stain resistance.After contamination test,the cooling value of coating decreased by 0.7?.The anti-aging performance of waterborne epoxy heat-reflective coating was evaluated by indoor simulation aging and outdoor natural aging.With the simulation aging time increased,the cooling values of heat-reflective coating decreased.After 6 months of outdoor natural aging,the cooling effect and anti-skid performance decreased.The coating pavement still maintained a good state,but the cooling effect and other pavement performance declined after 6 months.Adding 1% complex light stabilizer?UV-531:GW-480=1:1?could effectively improve its anti-aging performance.Through the indoor and outdoor cooling experiment,it could be found that the heat-reflective coating with light stabilizer after aging could also maintain a better cooling effect. |
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