Research On Determination Of Thermal Properties Of Asphalt Pavement Materials

The temperature field analysis of asphalt pavement has important applications in many aspects,such as determining the opening time of newly paved roads and reducing the urban heat island effect.When analyzing the temperature field of the asphalt pavement,in order to ensure the accuracy of the calculation results,it is necessary to input the relevant thermophysical parameters of the asphalt mixture as accurate as possible.At present,there is no unified method for determining the thermophysical parameters of asphalt mixture in the relevant codes of domestic and foreign road engineering.Providing a convenient and accurate method for testing the thermophysical parameters of the mixture can promote the related research on the temperature field of the road surface,and provide relevant guidance for improving the performance of the road surface and reducing the urban heat island effect.Based on the theory of heat transfer,this thesis proposes a test method based on the principle of transient heat conduction.The thermophysical properties of asphalt mixtures of different gradations are tested,and the thermal conductivity obtained is verified by the steady-state method.The results show that the difference between the results obtained by the two methods is less than 5%,so the transient test method proposed in this paper can obtain accurate thermal conductivity values,and compared with the general steady-state method,it saves nearly40%of the test time.According to the relationship between thermal conductivity,thermal diffusivity,and specific heat,a specific heat experiment was designed to verify the thermal diffusivity.The results showed that,with the exception of specimen A-2,the error value of the calculation results of the test results were all within 5%.Secondly,this thesis compares and analyzes the existing finite element methods of calculating the thermal conductivity of asphalt mixtures at domestic and abroad,and chooses a suitable method to verify the thermal conductivity test results.After the model is reproduced,two sets of asphalt mixtures with different gradations are selected to determine the thermal conductivity values of the aggregate and asphalt,6)6)_{（6（6） and6）6（7（7）,and then the remaining two sets of gradation asphalt mixtures are calculated based on the obtained6）6（6（6） and6）6(}(7（7）.The results show that the error between the finite element calculation results and the test results is around7%,which verifies the accuracy of the test data.It can be concluded in the calculation process that the thermal conductivity of aggregate has great influence on thermal conductivity of the mixture,while the thermal conductivity of the asphalt has almost negligible effect on the thermal conductivity of the mixture.