| In order to cool asphalt pavement in high temperature seasons and alleviate the urban heat island effect,this paper focused on functional materials to prepare reflective cooling coating with excellent optical and mechanical properties.Potassium titanate whisker（PHW）with outstanding mechanical strength and high reflectivity is selected as the main functional material,and nano-Ti O2 and flake nano-Cu O are used as regulating materials.The reflective cooling coating of asphalt pavement with balanced performance was developed by PHW inorganic-organic surface modification and functional materials composition design.Firstly,the mixture composed of epoxy resin,sulfhydryl curing agent（TMPMP）and Tris（dimethylaminomethyl）phenol（DMP-30）is used as the matrix of the coating.The amount of curing agent and curing accelerator in the mixture was determined by the tensile strength of the matrix and the surface-drying time of the curing system.The performance of the coating matrix is better when the ratio of epoxy resin,curing agent and curing accelerator is 100:58:0.8（in gram）.Secondly,in order to enhance the interface bonding between PHW and matrix,improve the dispersion of PHW in resin matrix and optimize the performance of coating using PHW as functional material,the PHW was treated by inorganic-organic surface modification（Zn O coated PHW was prepared via a facile chemical method,and then the coupling agent KH570was used to modify the surface of Zn O coated PHW）.A variety of testing methods were employed to test the dispersion of whisker in coating,as well as reflectivity,tensile strength,bending strength and wear quality of the coating before and after surface modification of whisker,the strengthening effect of PHW surface modification on the coating was characterized qualitatively and quantitatively.It was found that after surface modification of PHW,the dispersion of PHW in coating was improved;when the PHW content was 15 phr,the reflectivity of the coating increased by 10.04%;the whisker surface modification significantly enhanced the tensile strength and bending strength of the coating;the surface modification decreased the wear quality of the coating as a whole.Specifically,the 200s wear quality of the coating decreased from 3.03g to 2.64g when the whisker content was 16 phr.Thirdly,using inorganic-organic surface modified PHW as the main wear resistance enhancement material,nano-Ti O2 and flake nano-Cu O as the main optical performance optimization materials,a three-factor and four-level orthogonal experiment was designed.The effects of functional materials on reflectivity,brightness,tensile strength,wear quality and economy of coating were studied by analysis of variance and range analysis,and multi-index comprehensive balance evaluation was carried out to determined the functional materials composition of the coating with the best-balanced performance.The results showed that Ti O2and Cu O have a significant effect on the optical properties of the coating,and surface modified PHW affected the mechanical properties of the coating significantly.The materials composition makes the best-balanced functional coating are 11 phr of modified PHW whisker,0.5 phr of nano-Ti O2 and 1 phr of nano-Cu O（A3B2C2）based on multi-index comprehensive evaluation of coating reflectivity,coating brightness,wear quality and economy of coating.Finally,the coating was prepared according to the obtained composition of the functional materials,and the cooling performance,adhesion performance,skid resistance and wear resistance of the prepared coating were tested.In addition,the water resistance and corrosion resistance of the coating were verified.The test results showed that the surface temperature of the coating specimen with the amount of 0.8kg/m2 coating is 8.1℃lower than that of the control specimen,and the 48h average pull-out bond strength is 0.994MPa.The BPN of the asphalt concrete slab is reduced from 71 to 54 because of coating,and the wear life of the coating is about 200000 times,which is 100000 times higher than the coating without modified PHW.The coating did not appear softening,discoloration,wrinkling,blistering,shedding or cracking after immersing in saturated Ca（OH）2 solution at room temperature or water at 60℃for 24 h,which indicated good water resistance and corrosion resistance. |
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