Study On Dynamic Modulus And Fatigue Performance Of Asphalt Mixture Based On Trapezoidal Cantilevered Test Beams In France

Asphalt mixture is a typical viscoelastic material,which is not only sensitive to temperature and frequency,but also has obvious stress dependence.The mechanical response is obviously different under static load and dynamic load.At present,foreign countries have already adopted the dynamic modulus as a design parameter into the pavement design method.Therefore,based on the national conditions of China’s road construction,it is very important to study the dynamic modulus of asphalt mixture gradation commonly used in China.On the other hand,according to the summary of experience in the use of semi-rigid base asphalt pavement over the past two decades,it has been found that fatigue failure has become a persistent problem for asphalt pavements.Therefore,for the relevant research on the fatigue performance of asphalt mixture,it is particularly urgent to analyze the main factors affecting the fatigue life of asphalt mixture.In this paper,with reference to the French standard,a dynamic modulus test is performed on the commonly used gradations in domestic pavement design used in full-scale loops in China using trapezoidal beam equipment.First of all,using the advantages of trapezoidal beam equipment to carry out experimental design,testing the dynamic modulus of 10 commonly used asphalt mixture gradation,mainly to investigate the impact of temperature,frequency and strain on the dynamic modulus of asphalt mixture,analyzed The influence of various influencing factors on the dynamic modulus,and according to the principle of time temperature equivalence,the dynamic modulus master curve was plotted.The results show that the dynamic modulus of asphalt mixture decreases with the increase of temperature.With the increase of the loading frequency,the dynamic modulus of its amplitude is up to 58%,and its dynamic modulus varies by up to 30%with the strain level.,showing obvious strain dependence.Through the dynamic model.The analysis of the characteristic points of the master curve gives the experimentally graded dynamic bending modulus values.Then,the advantages of DMA(Dynamic Mechanics Analysis)and SPT(Simple Performance Tester)test equipment were used to carry out experimental design.Using DMA and SPT dynamic modulus tests to compare and analyze the influencing factors of dynamic modulus,draw a dynamic modulus master curve.At the same time,the results of three different dynamic modulus tests were analyzed in depth.Through comparison of model tests and measured deflections with simulated deflections,it was found that the SPT test results are more stable and consistent with the actual ones and have strong practical value.It is more conducive to guiding engineering practice.A fatigue test was conducted on the gradations of the five commonly used asphalt mixtures in the upper and lower layers of the country to explore the effects of mixture grading due to the advantages of the trapezoidal beam tester,loading frequency and asphalt materials on the fatigue life of the asphalt mixture,and according to the new version The content of the fatigue of asphalt mixture in the<Design Specification for Highway Asphalt Pavement>(JTG D502017)compares and analyzes the considerations in the design of fatigue in the two countries.It was found that the grade of bituminous mixture significantly affects its fatigue life,and the fatigue life of bituminous mixture decreases with the increase of the loading frequency.At the same time,it is found that the calculation and control standards for fatigue life are comparable in the specifications of both countries.