Research On Characterization Method Of Asphalt Mixture Dynamic Modulus Under Different Stress State And Temperature And Frequency Conditions

In the actual use process of asphalt pavement,each structural layer of the pavement responds dynamically to the dynamic load of the vehicle.As a very important dynamic parameter,the dynamic modulus can reflect the actual force condition of the pavement under the wheel load.Analyze the important parameters of the stress-strain relationship of asphalt pavement structure.Since the indoor test measurement of dynamic modulus is greatly affected by temperature and loading frequency,and has a certain time-temperature equivalence,it is necessary to study the law of dynamic modulus under different temperature and frequency.In addition,the measurement of dynamic modulus is also greatly affected by the indoor loading method.When different loading methods are used for measurement,it often means that the stress state of the test piece is quite different,and the dynamic modulus obtained is also obviously different.To this end,this paper carried out the tensile,compression,and split dynamic modulus tests under five test temperatures and six loading frequencies,and carried out the study of the dynamic modulus under different stress states and temperature and frequency,and obtained the corresponding dynamic modulus.The volume master curve and prediction model provide a certain reference for the prediction of dynamic modulus under wide-range test conditions.Through dynamic modulus tests at different temperatures and loading frequencies,the dynamic modulus of asphalt mixture changes with temperature and loading frequency,that is,the change of dynamic modulus within a certain range is negatively correlated with the change of test temperature.Is positively correlated with the change of loading frequency.Under the same test conditions,the relationship between the dynamic modulus values of the three loading methods is:uniaxial compression>indirect stretching>direct stretching.Through the comparative analysis of the dynamic modulus values under different stress levels,it is obtained that the dynamic modulus value increases with the increase of the stress level,and the stress level is introduced into the master curve to establish the corresponding dynamic modulus master surface.Based on the relevant theories and research on time-temperature equivalence,by fitting and analyzing the dynamic modulus test data at different temperatures and loading frequencies,the dynamic modulus master curves under three loading methods are obtained,using Sig-moidal the function fitting the dynamic modulus master curve has a good fitting effect,and the corresponding master curve shift factor is fitted and analyzed based on the WLF equation.Combining the Sig-moidal model and the WLF equation,the three loading modes are derived the dynamic modulus prediction model.By comparing and analyzing the dynamic modulus values under the three loading methods,the conversion equations of the dynamic modulus prediction models under different loading methods are established.Finally,based on the indoor test results in this article and the corresponding derivation model,the representative value of the permanent deformation dynamic modulus of the typical pavement structure layer is predicted.The research results in this paper can provide a certain reference for further eliminating the influence of loading methods on the dynamic modulus,establishing a unified prediction model,and providing important parameters for the prediction and analysis of the equivalent temperature of permanent deformation and fatigue life.