The Research On Performances Of Sodium Alginate/SBS Composite Modified Asphalt And The Mixture

The performance of asphalt will affect the service life of asphalt pavement.Asphalt tends to aging by exposure to the environment duing the service,and this will result in shorter service life of asphalt pavement than the design years.Styrene-butadiene-styrene(SBS)modified asphalt is one of the most widely used modified asphalt due to its superior performance,such as good properties of high and low temperature and fatigue characteristics.However,SBS modified asphalt is prone to aging due to the double bonds in SBS,which shortens the service life of pavement,as a result of the peeling off of aggregate and asphalt after water.In this paper,sodium alginate,a kind of natural polymer material with thickening and viscosity effect is selected as the modifier of SBS modified asphalt.The properties of high and low temperature,the anti-aging performance and the water stability of the mixture are improved due to the superior performance of good viscosity thickening and efficient material reinforcement.(1)Asphalts with different dosages of SBS were tested with the rotational film oven(RTFO),and the relationship between the aging performance and viscosity of asphalt was characterized by penetration,dynamic shear rheometer(DSR)test and Fourier transform infrared spectroscopy(FTIR).Comparing sodium alginate/SBS composite modified asphalt with SBS modified asphalt,the softening point and viscosity of asphalt increased,penetration and ductility decreased,and the high temperature performance of asphalt was improved.(2)Sodium alginate can slow down the effect of RTFOT and the pressure aging vessel(PAV)aging on the softening point of SBS modified asphalt and resist the change of asphalt hardness,compared with the physical properties before and after aging of sodium alginate/SBS composite modified asphalt.The DSR test results showed that sodium alginate can slow down the effect of aging on the high temperature rheological properties of asphalt.The bending beam rheometer test(BBR)showed that sodium alginate could delay the effect of aging on the creep stiffness modulus of SBS modified asphalt.Sodium alginate can reduce the effect of aging on asphalt viscosity.The aging performance of sodium alginate/SBS modified asphalt is better than SBS modified asphalt.And the optimum dosage is 1%sodium alginate+4.5%SBS.Base asphalt,SBS modified asphalt and sodium alginate/SBS composite modified asphalt were observed by Fluorescence microscope,and it was found that sodium alginate improved the dispersion effect of SBS modified asphalt and enhanced the anti-aging performance.(3)The moisture stability,high and low temperature properties of SBS modified asphalt mixture and sodium alginate/SBS composite modified asphalt mixture were evaluated with adhesion test,immersion Marshall test,freeze-thaw cleavage test,wheel tracking test and bending test,respectively.It was found that sodium alginate/SBS composite modified asphalt mixture have a better water stability and a better high temperature performance,compared the residual stability,the freeze-thaw cleavage strength and the dynamic stability of sodium alginate/SBS composite modified asphalt mixture with SBS modified asphalt mixture.