Test Research On Resilient Modulus And Fatigue Property Of Asphalt Mixtures

Because asphalt pavement is of flat surface,jointless,comfortable running, simple maintenance and short-time construction,it has become the major structural style of high grade highways.Firstly,in this paper the causes and types of fatigue crack of asphalt pavement are theoretically analyzed,then based on the design,construction and maintenance,the prevention measures of fatigue crack are discussed.To improve the manufacturing quality of specimen,reacting force support is self-manufactured,the forming of specimen should be more standard.Secondly,when it is determined that the compressive strength and compressive resilient modulus of asphalt mixtures with different asphalt content(3.8%,4.3%,4.8%,5.3%,5.8%)according to uniaxial compression test, failure form and stress-strain relationship curve of asphalt mixtures;asphalt mixtures dynamic compressive resilient modulus is preliminary studied.Finally,using the principle of ultrasonic detection,the strength of fatigue specimen is predicted,the fatigue life is determined according to fatigue test,and predicted by dissipated energy theories.According to test results,it is discovered that the compressive strength of asphalt mixtures increases with the decreasing of asphalt content in the range of test,but when asphalt content decreases continuously from 4.8%,it also decreases.The compressive resilient modulus increases with the decreasing of asphalt content,and asphalt content corresponding peak value lags behind of the optimum bitumen content in marshal test, so asphalt content can decrease appropriately in the design,which will be good for the improvement of design parameters.Stress-strain relationship curve of asphalt mixtures can be divided into 4 stages:back bending part,linear part,hyperbola part and rupture part,strain at peak stress is about 0.004.In order to advance design theory of asphalt pavements transition from static to dynamic,static compressive resilient modulus is converted into dynamic based on the relationship of dynamic and static compressive resilient modulus.Fatigue strength of asphalt mixtures can be predicted through the principle of ultrasonic wave before fatigue test,predicting equations are f=0.0005×e^0.002νR²=0.9633(25℃),f=0.0002×e^0.0025νR²=0.9306 (-5℃),it is proved that ultrasonic velocity has a well relation with strength,and sound velocity can be used to better predict fatigue strength of asphalt mixtures.The fatigue life of asphalt mixtures obeys double logarithm fatigue equations,which are N_f=30.931(1/σ)^1.5388(25℃),N_f=123.61(1/σ)^1.3928(-5℃),The good relation between dissipated energy and fatigue life of asphalt mixture is proved through experiments, which are W_F=0.05569×N_F^0.8764(25℃),W_F=0.01555×N_F^1.1453(-5℃), dissipated energy can reflect better fatigue process,and it is an effective method to analyze and forecast fatigue property.It is instructive to design and site operation of asphalt pavement.