Back-calculating The Key Performance Index Of The Surface Of Asphalt Pavement Based On Dielectric Constant Test Model

Ground Penetrating Radar(GPR)is a speedy,continuous,non-destructive and effective testing technology using broad-spectrum electromagnetism technique for detecting the distribution of underground structures.At present,GPR has been an important part of non-destructive testing technology for road.Asphalt Concrete pavement is an important type of road in our country.We use compaction,void ratio and asphalt content as the main indexes of pavement construction quality and acceptance of the project.The dielectric constant model of asphalt concrete materials is the foundation of identification for properties of asphalt concrete pavement based on the GPR.The current research for dielectric constant model mainly focus on microwave remote sensing,logging and other fields.Most of the existing dielectric constant models have been established for soil and rock.However,research for the dielectric constant model of asphalt concrete material is relatively short.Aiming to the current situation above described,the complex dielectric properties model for asphalt concrete is studied in this paper.The main contents and conclusions are as follows:1)The dielectric properties of dielectric and the basic theory of dielectric polarization are discussed,Wave guide is selected as the measuring method of experiment in paper by comparing and analyzing Coaxial Probe and Wave guide.2)Based on the test,the influence of some factors including the oil-stone ratio,asphalt type,frequency,aggregate gradation and void ratio on the dielectric constant of asphalt concrete material are analyzed.The results show that the oil-stone ratio and aggregate gradation has less influence on the dielectric constant of asphalt concrete materials,the frequency,asphalt type and void ratio has high influence on dielectric constant of asphalt concrete materials according to a define rule.3)Using the basic principles of electromagnetism and analyzing the polarization mechanism,the complex dielectric constant model of asphalt concrete material is established based on the microscopic model.The rationality of the complex dielectric constant model is validated,and the model is modified based on data by experiments.The comparative analysis is done between the complex dielectric constant model and several classical model,The results show that the complex dielectric constant model established in paper has higher accuracy and is more suitable to explain the dielectric properties of asphalt concrete material.4)The method for inverse analysis of the compaction,void content and asphalt content ect.is put forward based on the theory for inverse analysis of complex dielectric properties of layered structures and the complex dielectric constant model for the asphalt concrete material.