| Bio-asphalt has significant advantages such as huge reserves,environmental protection and regeneration,comprehensive sources,and low price.However,due to its highly complex production raw materials and production methods,the properties of different bio-oils are very other,making it difficult for bio-oil to be applied to engineering practice.This paper aims to compare the high-and low-temperature rheological properties of different types of bio-asphalt,compare the micro-characteristics of bio-asphalt,and analyze the relationship between the macro-performance and micro-characteristics of bio-oil to promote the application of bio-oil in engineering practice.Five different bio-oils(castor oil,straw oil,soybean oil,waste oil,and vegetable oil)were used to regenerate the aged asphalt after short-term and long-term aging to prepare the recycled asphalt.A series of routine,rheological,and micro tests were used to analyze and study the performance and regeneration mechanism of different kinds of bio-oil recycled asphalt with other content.Based on the indoor test results,the main research results are as follows:(1)Based on the results of routine performance test and dynamic shear rheometer test,bio-oil increases the penetration and non-recoverable creep compliance of asphalt and reduces the softening point,rutting index,strain recovery rate,storage modulus,and loss modulus of asphalt,indicating that bio-oil reduces the rutting resistance,viscosity,and elastic properties of asphalt.(2)The ductility test results show that bio-oil will improve the ductility of asphalt.The bending beam rheometer test shows that bio-oil will reduce the stiffness modulus of asphalt and increase the creep rate of asphalt.The addition of bio-oil will make asphalt more prone to plastic deformation when under stress to resist the damage brought by stress.(3)Fourier transform infrared reflection results show that the process of bio-oil regenerating asphalt is physical blending.The analysis of bond and index shows that bio-oil has a good regeneration effect on asphalt,but there is no obvious evidence that the absorption peak of bio-oil corresponds to the regenerated asphalt;Scanning electron microscope test shows that aging will crack asphalt,but the addition of bio-oil can restore the crack.(4)Through thermogravimetric analysis,Thermogravimetric Analysis test results show that bio-asphalt has an apparent mass loss from 300℃ to 400℃,and the quality is stable at about 500℃ to 600℃.Both the initial loss temperature and the stable quality temperature are related to the performance of recycled asphalt.Gas chromatography-mass spectrometry test shows that the chemical components of bio-oil are very complex,and there are significant differences in the chemical components of different types of bio-oils.The chemical components of bio-oil are well related to recycled asphalt,especially the content of organic esters and hydrocarbons in bio-oil.The macro performance of asphalt has no significant relationship with the molecular weight of bio-asphalt obtained by mass spectrometry.It has a special relationship with the molecular weight obtained by the Gel permeation chromatography test.However,it will be affected by some specific substances(phenolic compounds)in some bio-oil. |
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