Preparation And Properties Of Micro/Nanomaterials Modified Asphalt

Micro/nanomaterials are different from ordinary materials due to their large specific surface area,small size,etc.,and have some novel and peculiar characteristics in light,electric and magnetic fields,which make them very important in the fields of energy,catalysis and environment.As an important building material,asphalt has been widely used in road construction,waterproofing,anti-corrosion construction,etc.The problem of asphalt aging and the pollution of heavy metals in the soil environment of the road and its surrounding road caused by asphalt road traffic have been seriously considered by people.This dissertation takes micro-nano modified bitumen as the research object,mainly discuss the application of micro/nanomaterial modified bitumen in improving asphalt aging,and the application of micro/nanomaterial modified bitumen in the treatment of heavy metal Cr???pollution.In this paper,aromatic oil sustained-release microcapsules were prepared by emulsification solvent evaporation method,and the optimum preparation parameters were determined.The optimum preparation parameters were as follows:the selection of gelatin SDS composite phase as emulsifier,the shear rate of 700r/min,the mass ratio of core material/wall material of 1:1,and the better microcapsules.The sustained-release properties of the microcapsules were studied by using the thermal volatilization weight loss test.The results showed that the microcapsules can significantly slow the release rate of aromatic oils.Modified asphalt was prepared by adding slow-release microcapsules into bitumen,and RTFOT tests were carried out on the original asphalt and microencapsulated asphalt,and a series of performance test tests were performed on the original asphalt and microcapsule modified asphalt before and after aging.It mainly includes three major performance index tests,viscosity test,and dynamic shear rheological test?DSR?.The influence of the addition of microcapsules on asphalt performance was analyzed.The results show that microcapsules can provide certain light components during the short-term aging process,slow down the asphalt aging process.In view of the heavy metal Cr???pollution on road surface,the modified asphalt membranes were prepared by using carbonyl iron powder and nano-TiO₂/g-C₃N₄ composite materials,respectively,and their properties of reducing Cr???were studied.By optimizing the preparation process of carbonyl iron powder modified asphalt film,the results show that the carbonyl iron powder content is 7.6%,the thickness of the asphalt film is 0.235mm,and Cr???solution concentration is 1mg/L,the Cr???reduction is most beneficial.In the reaction,the reduction rate reached 89%within 4 days.Nanosized TiO₂/g-C₃N₄ composites were successfully prepared by molten salt method.The morphologies and crystal structures of TiO₂/g-C₃N₄ composites were characterized by SEM and XRD.The results show that g-C₃N₄ and TiO₂ form a compact composite structure and g-C₃N₄ is a square hollow nanotube structure.The samples were characterized by UV-Vis diffuse reflectance spectroscopy and fluorescence spectroscopy.The results show that the composite TiO₂/g-C₃N₄ has better optical properties than single TiO₂ and g-C₃N₄.The Cr???solution was reduced under visible light irradiation to further confirm that the photocatalytic activity of TiO₂/g-C₃N₄ was optimal.The TiO₂/g-C₃N₄ was loaded on bituminous materials by mixing and coating methods,respectively,to discuss the effect of the addition method on Cr???reduction.The results show that the Cr???reduction effect under visible light irradiation is better when the bitumen film is loaded with the mixing and coating method,and the degradation of the Cr???mixture has more than two other trends as the time goes by.However,the mixing time is very sensitive to Cr???reduction in the sample,indicating that the mixing method is more suitable for engineering applications.In order to further evaluate the photocatalytic activity of TiO₂/g-C₃N₄ mixing asphalt,different influence factor was studied by photocatalytic experiment.It was found that the efficiency of reducing heavy metals Cr???was the highest when the amount of Cr???was 5%and the initial Cr???concentration was 2.5mg/L.