| As a product of crude oil processing,petroleum asphalt is a non-renewable resource.The 14th Five-Year Plan for Highway Development issued by the Ministry of Transport in 2022 clearly points out that during the 14th Five-Year Plan period,China’s highway transportation should implement the concept of green development,promote the coordinated development of highway transportation and ecological protection,continue to deepen the construction of green highways,promote the economical and intensive use of resources and energy,strengthen energy conservation,emission reduction and pollution prevention in the field of highway transportation.We will comprehensively improve the green development of the highway industry.Therefore,finding more environmental protection and energy saving materials to replace or partially replace the petroleum asphalt is one of the major problems facing the field of asphalt pavement construction,but also for our road industry continued green development is of great significance.Bio-oil and diatomaceous earth,as green and environmentally friendly biomass resources with wide sources and low prices,have been widely used as new road materials in recent years to replace or partially replace petroleum asphalt.In this paper,rapeseed heavy oil and diatomaceous earth obtained from pyrolysis of rapeseed oil residue were used as raw materials to prepare rapeseed heavy oil-diatomaceous earth composite modified asphalt by adding them into 70#matrix asphalt as composite modifier.By studying the conventional properties,rheological properties,micromechanism of asphalt and pavement properties of the mixture,the following conclusions are obtained:(1)Through orthogonal test,the optimum preparation parameters of rapeseed heavy oil-diatomaceous earth composite modified asphalt were determined as the content of diatomaceous earth 5%,the shear time 35min,and the shear rate 2500r/min.(2)The test results of conventional properties and rheological properties show that rapeseed heavy oil and diatomaceous earth can make up for each other’s adverse effects on asphalt properties,and various properties of rapeseed heavy oil-diatomaceous earth composite modified asphalt are superior to matrix asphalt,which has better temperature sensitivity and good high and low temperature performance.(3)The results of infrared spectrum and nuclear magnetic resonance hydrogen spectrum analysis show that when rapeseed heavy oil,diatomaceous earth and matrix asphalt are mixed,the main physical reactions dominate,and also contain weak chemical reactions under coupling action,but basically do not change the original physical and chemical properties of asphalt,and can retain the asphalt’s own characteristics.The results of atomic force microscopy show that the addition of rapeseed heavy oil and diatomaceous earth can increase the number of bituminous bee structure,the shape becomes smaller,the distribution is more uniform,the area proportion increases,and the viscosity elasticity and high temperature stability of bituminous are improved.The results of differential scanning calorimetric analysis and thermogravimetric analysis show that rapeseed heavy oil,diatomaceous earth and matrix asphalt can be evenly mixed,and the reforming of asphalt colloidal structure by diatomaceous earth is beneficial to the stability of asphalt component properties,and can significantly improve the temperature stability of asphalt.The thermal stability of rapeseed heavy oil-diatomaceous earth composite modified asphalt is better than that of matrix asphalt.(4)The road performance of AC-13C asphalt mixture is studied.The results show that under the synergic action of rapeseed heavy oil and diatomaceous earth,the rapeseed heavy oil-diatomaceous earth composite modified asphalt mixture has better performance than the matrix asphalt in all aspects,and has good rut resistance and low temperature crack resistance,as well as good water stability.(5)Through comprehensive analysis of the effects of rapeseed heavy oil and diatomaceous earth on the properties of asphalt bonding(mixing)compound,it can be seen that rapeseed heavy oil-diatomaceous earth composite modified asphalt bonding(mixing)compound has good high and low temperature properties,and has wide application areas and broad application prospects.The use of rapeseed heavy oil and diatomaceous earth to prepare composite modified asphalt is beneficial to make full use of biomass energy and save asphalt materials,and provides the corresponding theoretical reference for the design and application of rapeseed heavy oil and diatomaceous earth in asphalt pavement engineering.It is of great significance for improving pavement performance,reducing oil dependence and protecting ecological environment,and has important engineering practical value. |
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