Research On The Dynamic Resilient Modulus With Its Master Curve Of Asphalt Mixture

In our country,asphalt pavement design method using 20 degree Static creep modulus as asphalt pavement surface deflection design calculation parameters,using 15 degree Static creep modulus as asphalt pavement bottom layer tensile stress design calculation parameters.Although static creep modulus to some extent could reflect asphalt pavement mechanical response,but the limitations were relatively large,the temperature ranges were narrow,and ignore the influences of asphalt pavement responses caused by loading waves.In many foreign asphalt pavement design method,including the widely influential MEPDG design method,using the half sine continuous loading manner to obtain the dynamic modulus as the asphalt pavement design calculation parameters.Compared to static creep modulus values,dynamic modulus test considered different temperatures,the testing method adapt the dynamic loading and got different temperatures,different frequencies dynamic modulus values,so it could better reflect the realities of the asphalt pavement.Nevertheless,even the common used dynamic modulus,the preferred measurement procedure AASHTO TP62-03,laboratory loading waveform considered very simple,only half sine loading wave,without considering the changes of loading waves in the direction of depth,from square wave fade into half sine wave,with the increase of depth,fade into bell wave.On the other hand,vehicle loading on the asphalt pavement,between the shaft and the shaft of a single vehicle,and between the vehicle and the vehicle,existed short or long intermittent time.During the intermittent time,no vehicle loads on the asphalt pavement.That was said,after a vehicle loading,before the next vehicle loading,asphalt pavement would have a "rest" time,namely Rest Period.During the rest period,asphalt pavement would have a elastically resilient recovery process.In the laboratory,to simulate this process,the rest period should be considered between loading waves.Dynamic resilient modulus considered the existence of rest period.Therefore,the dynamic resilience modulus under different load waveforms could better simulate actual conditions of asphalt pavement.Unfortunately,dynamic modulus testing methods did notconsider the influence of rest period.Because the present asphalt mixtures dynamic modulus testing procedures did not conside the loading wave and rest period.So far,the true sense of the asphalt mixture dynamic resilient modulus had not been received t home and abroad.But doing the dynamic resilient modulus in the laboratory would be limited by the devices.So it was difficult to obtain asphalt mixture dynamic resilient modulus under extreme conditions.Using the measured dynamic resilient modulus to fit the Master Curve,which could make up the laboratory test,due to equipment limitation,Then obtain asphalt mixture dynamic resilient modulus under extreme conditions.Firstly,by using universal testing machine UTM-100 custom block UTS 019 write program to consider different loading waves which consist of square wave,half sine wave,and bell wave.At the same time,achieving the freedom adjustment of Rest Period vs Loading Times.So loading waves can be select between square waves,have sine wave,bell wave.Therefore,it is possible to obtain square wave,have sine wave,bell wave asphalt mixture dynamic resilient modulus.Then,using square wave,have sine wave,bell wave asphalt mixture dynamic resilient modulus,by nonlinear least multiplication to fit square wave,have sine wave,and bell wave dynamic resilient modulus Master Curve.At last,using asphalt pavement different depth loading wave dynamic resilient modulus Master Curve,to obtain corresponding temperature and frequencies dynamic resilient values which could be used as finite element calculation parameters,to conduct asphalt pavement finite element calculation and obtain asphalt pavement structure mechanical response,so that the So that the calculated results is closer to the true value.