Study On Effect Of Temperature And Frequency On Modulus Of Asphalt

Asphalt mixture is a kind of viscoelastic material,and its mechanical properties are very different at different temperatures and loads.In our country,the static modulus is taken as the design parameter in pavement structure.In fact,the temperature and the frequency of vehicle load of the same point on the road changes all the time.The use of static modulus as the design parameter can not reflect the actual situation of the road.It is an inevitable trend to design parameters from static modulus to dynamic modulus in pavement structure.Dynamic modulus is an important design parameter in dynamic design.Dynamic modulus is not only used for pavement dynamic design,but also is an important performance evaluation parameter.Therefore,studying the influence of temperature and loading frequency on dynamic modulus of asphalt can not only accelerate the change of the pavement structure design system,but also provide reference for making standard temperature of indoor dynamic modulus test.In this paper,based on the present research of dynamic modulus at home and abroad,it makes a detailed analysis of the stress-strain characteristics of asphalt mixture.By means of comparison and analysis of research methods of dynamic modulus at home and abroad,SPT(simple performance test)is used as the dynamic modulus test.Based on the scheme of test of AC13,AC20 and AC25,the dynamic modulus tests were performed under different loading frequencies(25Hz,20 Hz,10Hz,5Hz,2Hz,1Hz,0.5Hz,0.2Hz,0.1Hz)and different temperatures(5 ?,15 ?,25 ?,35 ?,40 ?,48 ?),and analyzes the influence of loading frequency and temperature on the dynamic modulus.Based on the comparison and analysis of the relationship between dynamic modulus and temperature and loading frequency at home and abroad,a simple regression relationship model between the dynamic modulus and temperature of asphalt mixture is obtained.As a comparison,the static modulus test was carried out,and the regression curve between static modulus and temperature was determined.The relationship between the ratio of the static modulus and dynamic modulus and the temperature is obtained.Through the analysis of the test results and theoretical study,the following conclusions can be obtained:the temperature is higher,the dynamic modulus is smaller,and the dynamic modulus decreased faster while the temperature is below 25?;with the loading frequency increasing,the dynamic modulus increases,but the increasing rate decreases,at a higher frequency,dynamic modulus is almost constant;with higher temperature and smaller frequency or lower temperature and higher frequency,the modulus of asphalt mixture are small;regression curve of dynamic modulus and temperature is divided into two sections at 35?;when the temperature is from 25? to 30?,the difference between dynamic and static modulus reaches maximum.