Study On Color Durability Of LDHs To Improve Color Thin Layer Pavement

In recent years,colored pavements have been widely used in urban greenways,bicycle lanes,sidewalks,bus lanes,and other places due to their unique color advantages and the ability to enhance the urban charm,alleviate fatigue,and warn traffic.However,most colored pavements will fade to different degrees after 1 to 3years of laying,affecting their long-term use value.The photon energy of ultraviolet light in the solar spectrum is higher than the bond energy of most chemical bonds.Long-term ultraviolet irradiation causes molecular damage and discoloration of color pavement.It is worth exploring to improve or shield the damage of ultraviolet light on the color pavement to improve its color durability.In this paper,based on the research of polyurethane color thin layer pavement,SDS-LDHs were prepared by sodium dodecyl sulfate intercalation of magnesium aluminum carbonate hydrotalcite,and SDS-HMBA-LDHs was prepared by sodium dodecyl sulfate and 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid intercalation between Mg Al layer double hydroxides.XRD,FTIR,SEM,UV-VIS,and other means were used to characterize and analyze the crystal structure,microstructure,and UV barrier properties of the prepared LDHs UV barrier material.The prepared LDHs UV barrier material was mixed into a polyurethane color coating to prepare the thin color layer,and a xenon lamp aging test was carried out.The influence of different LDHs and UV barrier material content on the color durability of the thin color layer was explored.A basic performance test evaluated the influence of LDHs UV barrier color on fundamental technical indexes of the color thin layer.The influence of SDS-HMBA-LDHs on the mechanical properties of the color thin layer was further studied by UV aging test,and the construction method of the color thin layer and the construction process of the color thin layer using the color mortar method were summarized.The main results of this paper are as follows:（1）The co-precipitation method successfully prepared the SDS-intercalated Mg-Al carbonate hydrotalcite.Compared with Mg₂Al-CO₃-LDHs,the SDS-LDHS sheet obtained after SDS intercalation has better dispersion,lower agglomeration,larger specific surface area,and a particular improvement in UV barrier performance.（2）The co-intercalated Mg-Al hydrotalcite with SDS and HMBA was successfully prepared by the co-precipitation and ion exchange method.According to the change of the spacing between the layers of layer double hydroxides and the structure size of the guest molecules between the intercalated layers,it is inferred that SDS and HMBA cross-arrange between the Mg Al layer double hydroxides.The average size of Mg₂Al-NO₃-LDHs,HMBA-LDHs,and SDS-HMBA-LDHs are 62nm,79nm,and 95nm,respectively.The UV absorption properties of the three LDHs UV barrier materials measured in the dry state and dispersed in an aqueous solution were SDS-HMBA-LDHs>HMBA-LDHs>Mg₂Al-NO₃-LDHs.（3）After 700h xenon lamp aging,the color difference of SDS-LDHs/color thin layer is smaller than that without adding the color thin layer,and the color difference of color thin layer under different dosages of SDS-LDHs is 4%>1%>2%>3%.SDS-LDHs retards the aging and fading of the color thin layer by reducing the decomposition of polyurethane in color thin layer.Moreover,SDS-LDHs and color thin pencils are physically mixed,and the basic properties of color thin pencils,such as hardness,water resistance,alkali resistance,and wear resistance,are not affected.（4）With the prolongation of xenon lamp aging time,the chroma of the color thin layer gradually decreased,and the color brightness decreased.The color thin layer gradually changed to white,green,and yellow in the Lab color space,eventually leading to the color difference of the thin color layer.After 800h xenon lamp aging,the color difference of SDS-HMBA-LDHs/thin color layer is smaller than that of the color thin layer without adding.The color difference of color thin layer under different dosages of SDS-HMBA-LDHs is 1%>2%>3%>4%.According to the test results of color durability,optical properties,and basic properties,the optimal dosage of 3%is determined.In addition,the mechanical properties test found that adding SDS-HMBA-LDHs also helped improve the degradation of physical and mechanical properties of color thin layers caused by UV radiation.（5）The color thin layer pavement construction method mainly includes surface coating,color mortar,sand,and color micro surface methods.The construction process of the color mortar method mainly includes several steps of construction preparation,material preparation,color thin layer laying,and color thin layer health.