Research On The Properties Of Bio-char Modified Asphalt Based On Rheology

With the development of asphalt pavement construction,the demand of petroleum asphalt is increasing.As a non renewable fossil resource,the petroleum is also on the verge of exhaustion.And petroleum asphalt will produce a largr number of greenhouse gases in the process of production and using,which can accelerate the deterioration of the ecological environment and affect the construction and maintence of asphalt pavement.In order to reduce the using of fossil fuels,make full use of renewable resource,improve the defects of traditional asphalt,this paper uses bio-char as asphalt modifier to creact bio-char modified asphalt,which can improve the asphalt performance,reduce the cost of production,and help to realize the sustainable development of road materials.Based on the analysis of domestic and foreign documents,the proper size of bio-char and preparation method of modified asphalt were selected to study the properties of bio-char modified asphalt.In this paper,a large number of laboratory tests have been carried out to study the effct on the asphalt performance by using five kinds of modified asphalt with different amount of modifier.And the combination of routine test index(softening point,penetration,60 dynamic viscosity,short℃-term aging and long-term aging)and SHRP index(dynamic shear rheometer and bending beam rheometer)were used to evalue the properties of bio-char modified asphalt.From indoor experiments we can draw the following conclusions:(1)The linear viscoelastic range and homogeneous degree of bio-char modified asphalt are less than matrix asphalt.The more content of bio-char was,the smaller the linear viscoelastic range was.(2)The viscosity and rutting factor of bio-char modified asphalt were increased,and the absolute value of VTS was decreased by adding bio-char into asphalt,which indicated that bio-char could improve the high temperature performance and temperature sensitivity of asphalt.(3)To some extent,the low temperature performance of asphalt was decreased by the use of bio-char,but the reduction was not large.In order to improve the high temperature performance and do not affect the low temperature performance of asphalt,the content of bio-char must be controlled reasonably.(4)The complex modulus,rutting factor and softening point of matrix asphalt and bio-char modified asphalt were increased,and the penetration was decreased after aging,which showed that bio-char could improve the anti-rutting performance of asphalt.(5)The analysis of aging index and viscosity ratio showed that the anti-aging performance of bio-char modified asphalt was better than matrix asphalt.(6)Finally,the microstructure and chemical composition of the bio-char and asphalt were studied by Scanning Electron Microscopy(SEM)and Infrared Spectroscopy(IR)in this paper.The results showed that bio-char is porous structure that can be compatible with asphalt.Compared with the IR results of bio-char modified asphalt and matrix asphalt,there is no chemical reaction between bio-char and asphalt components.Bio-char modified asphalt can not only improve the performance of asphalt,but also make full use of waste resources whic has good economic and environmental benefits,and can provide reference for bio-char modified asphalt study and application in pavement engineering in China.