Study On Rheological Properties Of Bamboo Powder Modified Asphalt At High Temperature

With the rapid development of road industry,asphalt material has been widely used in pavement paving,but due to the harsh environment of asphalt pavement,the performance of asphalt has been put forward a huge test.However,due to the influence of test conditions and other factors,the rheological properties and fatigue properties of bamboo powder modified asphalt have not been improved,which has affected the promotion and use of bamboo powder modified asphalt.Therefore,it is particularly important to study the rheological properties and fatigue properties of bamboo powder modified asphalt and systematically analyze its various evaluation indexes.In this thesis,using rheological theory as reference,DHR-1 dynamic shear rheometer was used to carry out strain scan test,temperature scan test,frequency scan test,multiple stress repeated creep recovery test(MSCR)and time scan test on 90# asphalt and bamboo powder modified asphalt.The effect of bamboo powder on the rheological properties and fatigue properties at high temperature before and after short-term aging of 90#asphalt was studied.Main tasks completed include:(1)Study and analyze the preparation process of modified asphalt based on the three traditional asphalt indexes and the asphalt PG high-temperature grading system.(2)The strain scanning test was carried out on the asphalt,so as to find out the range of linear viscoelasticity before and after aging of 90# asphalt and the modified asphalt with each bamboo powder content under high temperature environment(46?--82?).The results show that the linear viscoelastic range of asphalt will become narrow with the increase of bamboo powder content.(3)On the basis of strain scanning test,temperature scanning test was carried out on each sample to analyze the change rule of its complex modulus,phase Angle,high temperature rutting factor and other indexes.The results showed as follows: a.the addition of bamboo powder could effectively increase the complex modulus of asphalt and inhibit the increase of phase Angle,thus increasing the rutting factor and improving the resistance ability of asphalt to rutting deformation,and the improvement effect was more obvious at high temperature than at low temperature;b.By comparing the critical temperature Ths of each asphalt sample before and after aging,it can be found that bamboo powder can effectively reduce the impact of short-term aging on asphalt performance,but it will have a certain negative impact on the aging rate of asphalt,which is not significant;c.Through the analysis of its viscose-temperature curve,it is found that the addition of bamboo powder can effectively reduce the temperature sensitivity of asphalt,so that the asphalt is suitable for a wider temperature range of road environment.(4)Frequency scanning tests were carried out on each asphalt sample within the range of linear viscoelasticity,and high temperature main curves were constructed for each asphalt according to the time-temperature equivalence principle.The results show that bamboo powder can effectively improve the temperature sensitivity and phase transition temperature of asphalt.(5)According to the test results of zero shear viscosity(ZSV)of each asphalt sample,it can be concluded that: At 46?,compared with 90# asphalt,the zero-shear viscosity of modified asphalt with different bamboo powder content is increased by31.0%、31.2%、38.1%、167.2%、201.0%、220.4% and 36.1%,respectively,indicating that bamboo powder can effectively improve the high temperature performance of asphalt.By calculating the viscosity-temperature index(VTS)of each asphalt sample,it is found that: Compared with 90# asphalt,the absolute viscosity temperature index of asphalt with each bamboo powder content decreases by 5.7%、5.2%、5.2%、8.1%、18.4%、19.7%、22.9% and 25.9%,respectively.The results show that bamboo powder can effectively improve the temperature sensitivity of asphalt,and when the bamboo powder content is 12%,the improvement effect is the most obvious.(6)Multiple stress repeated creep recovery test(MSCR)was carried out on each asphalt sample.The results show that the addition of bamboo powder can increase the strain recovery rate R and reduce the non-recoverable creep compliance Jnr,thus improving the high temperature stability of asphalt.(7)The linear viscoelastic range of each asphalt sample under the medium temperature environment(10?@25?)was determined by strain scanning test.On this basis,the time scanning test was conducted to study the influence of bamboo powder addition on the medium temperature fatigue characteristics of asphalt.The results show that the fatigue life of the asphalt increases by 1.3%、10.8%、37.9%、46.4%、37.4%、32%and 35%,respectively,compared with 90# matrix asphalt.The fatigue life of the modified asphalt with 12% bamboo powder is the largest,reaching 7229 times,and the fatigue life of the modified asphalt is increased by 46.4% compared with that of the matrix asphalt.When the bamboo powder content is more than 12%,the increase of asphalt fatigue life will decrease,and the increase of asphalt consistency is too high,which makes it very difficult for the instrument and on-site mixing.Although the fatigue life will be increased,it will cause a certain negative impact on other properties.In this thesis,the optimal dosage of bamboo powder modified asphalt is set as 12%.