| With the increasing traffic volume,the increasing traffic load,and the new trend of pavement development in modern highway construction,especially highway maintenance,the demand for asphalt materials is getting higher and higher.At present,the ordinary base asphalt used in road can not meet the requirements of daily transportation on the road,while modified asphalt has been widely used in road engineering because of its superior performance in both high and low temperature conditions.One of them,nano-materials modified asphalt materials and mainly nano-materials/polymer composite modified asphalt has shown special advantages in high temperature stability,low temperature crack resistance,durability,and water stability.In recent years,they have attracted wide attention that it becomes a new research direction and hot spot in the field of road materials.In this paper,there are two kinds of carbon nanoparticles,namely biobitumen based on carbon quantum dots and grafted modified petroleum pitch;they were prepared by pyrolysis,chemical oxidation and chemical grafting modification.The structure and the properties of the carbon nanoparticles were characterized.The carbon nanoparticles /SBS composite modifier was prepared by Pickering emulsion method with carbon nanoparticles as emulsifier.The paper also characterizes the performance of the composite modifier,investigates the influence of the composite modifier on the physical and rheological properties of the modified asphalt was investigated,and evaluate the performance of the composite modified asphalt mixture was evaluated.Bioasphalt based on carbon quantum dots were prepared by one-step pyrolysis using bioasphalt as carbon source.The microstructure,morphology and optical properties of the carbon quantum dots prepared at different pyrolysis temperatures were characterized by scanning electron microscopy,high resolution transmission electron microscopy,optical microscopy,Raman spectroscopy,Fourier transform infrared absorption spectroscopy,ultraviolet spectroscopy and fluorescence spectrometer.Bioasphalts based carbon quantum dots/SBS composite modifier was prepared by Pickering emulsion method using bio bituminous carbon quantum dots as emulsifier and characterized.The results showed that the bio bituminous carbon quantum dots exhibited excellent fluorescence properties after pyrolysis.Different pyrolysis temperatures showed significant differences in the luminescent properties and fluorescence properties of the bio bituminous carbon quantum dots.At the sametime,the bioasphalts based carbon quantum dots exhibited excellent surface activity.The Pickering emulsion prepared as emulsifier also showed high stability.Moreover,with the increase of pyrolysis temperature,the stability of the emulsion became more exceeding,and the stability of the carbon quantum dots Pickering emulsion prepared at 400?was the best.The experimental method boasts the advantages of simple process,simple preparation conditions,avoiding the use of acidic organic reagents,reducing production costs and environmental pollution,and cheap raw materials.It is suitable for large-scale production and application of nanosurfactants.Petroleum asphalt-based graphene quantum dots with asphaltene polycyclic aromatic hydrocarbon core were prepared by nitric acid oxidation from deoiled asphalt.The graphene quantum dots were chemically grafted with tetraethylene pentamine,hexamine,octadecylamine,dodecylamine and octadecylamine,respectively.Amide-based graphene quantum dots were prepared.The microstructure,morphology and optical properties of different types of petroleum pitch based graphene quantum dots were characterized by X ray diffraction,FT-IR and X ray photoelectron spectroscopy.Graphene quantum dots /SBS composite modifier was prepared by Pickering emulsion method with amide graphene quantum dots as emulsifier.The results show that there are a large number of carboxyl hydroxyl groups in petroleum asphalt-based graphene quantum dots.The covalent bond functionalization of petroleum asphalt-based graphene quantum dots is carried out by chemical grafting modification.The epitaxial carboxyl hydroxyl groups of petroleum asphalt-based graphene quantum dots have reacted with tetraethylene pentamine,n-hexamine,n-octylamine,dodecylamine and octadecylamine to form amide.Melene quantum dots have good water solubility,while the water solubility of amide-based petroleum asphalt-based graphene quantum dots decreases and shows oil solubility gradually;and the prepared petroleum asphalt-based graphene quantum dots have certain surface activity,tetraethylene pentamine petroleum asphalt-based graphene quantum dots and n-hexamine petroleum asphalt-based graphene quantum dots can be compoundedstabilize with SBS toluene solution so as to produce stabilized Pickering emulsion.The experimental method is a simple green method for preparing high-quality graphene quantum dots,which not only reduces the cost of the process,but also relieves the burden on environmental,and enjoys broad prospects.Two kinds of carbon nanoparticles/SBS composite modifiers were add to the base asphalt to prepare carbon nanoparticles/SBS composite modified asphalt and asphalt mixture.Their properties were analyzed by three indexes,viscosity,and rheology and road performance.The results show that for the bio-asphalt-based carbon quantum dots/SBS composite modifiedasphalt,the addition of bio-asphalt-based carbon quantum dots improves the high temperature performance and rutting resistance of SBS modified asphalt,but enhances its brittleness and decreases its cracking resistance at low temperature.For petroleum asphalt-based graphene quantum dots/SBS composite modified asphalt,there is an optimum content of petroleum asphalt-based graphene quantum dots/SBS composite modified asphalt.For high temperature performance,12.5% petroleum asphalt-based graphene quantum dots/SBS composite modified asphalt is recommended.With the low temperature performance,20% petroleum asphalt-based graphene quantum dots/SBS composite modified asphalt is recommended.Because of the surface activity,petroleum asphalt-based graphene quantum dots/SBS composite modified asphalt has warm mixing effect.The performance of petroleum asphalt-based graphene quantum dots/SBS composite modified asphalt mixture is similar to that of hot mix asphalt mixture at 175?under warm mixing at 155?,but the mixing temperature decreases by 20?,which reduces the construction temperature and harmfulness of asphalt mixture.At the same time,it ensures that the asphalt mixture has the same pavement performance and construction and ease as the hot mix asphalt mixture.It can be used in the process of road construction and maintenance,and it has broad application prospects. |
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