Research On Dielectric Property And Contruction Quality Assessment Of Asphalt Pavement Using Nondestructive Testing

The density index of asphalt pavement has significance influence over its quality and pavement performance. The core drilling method is recommended as a standard way to measure asphalt pavement density, which has the advantage of easy operation and perceptually accurate at the cost of damages to the original pavement. And only a limited number of data point can be obtained in this way. Hence, it is urgent to develop a fast, non-destructive and accurate asphalt pavement quality measurement technique as well as assessing system.Featuring wide range of measurement, high efficiency and accurate positioning, 3D ground penetrating radar has been widely applied in the areas including asphalt pavement thickness measurement, density prediction and pavement structural layer holes investigation. The common mid-point method is adopted here to calculate radar wave and obtain asphalt pavement permittivity. Then compare the obtained data with data from Adek permittivity determinator. According to electromagnetic theory, create asphalt pavement density prediction method based on permittivity and analyze its reliability and applicability. Put forward the method of second crest automatic drawing asphalt pavement thin layer bottom curve by means of discriminating radar wave trace line, which has made it possible for ground penetrating radar to effectively define different layers of asphalt pavement, enhancing efficiency and precision. In the meantime, measure asphalt pavement using PQI, mark segregation zone and nonsegregation zone and establish fitting formula for permittivity and density.This paper has provided both theoretical and practical foundation for assessing asphalt pavement quality with a basis on permittivity. Data from 3D ground penetrating radar are of dotted distribution. Permittivity is related to indexes including density, porosity, aggregate distribution and fatigue performance instead of isolated existence. From a microscomic perspective, this paper studies the relationship between aggregate spatial distribution and permittivity of asphalt pavement samples using industrial CT technique and fractal theory. It measures sample parameters including permittivity, density and fatigue life to help clarify the influence of permittivity over asphalt pavement performance and the according significance, further expanding the theoretical boundary and application range of 3D ground penetrating radar.Certain texture depth exists in the surface layer of asphalt pavement, providing sufficient anti-skid performance and further ensuring driving safety. However, because of the existence of surficial structure, permittivity contains the air information in surficial structure, causing errors in measurements, while its accuracy is directly related to the accuracy of 3D ground penetrating radar measurements including thickness measurements, quality measurements, disease measurements and void measurements. Although sand patching method is of easy operation and clear physical significance, it has the tendency of causing errors. Hence, this paper develops 3D laser scanner to measure the structural depth of asphalt pavement and calculate the proportion of air volume in the total asphalt pavement volume to correct the permittivity measuring results obtained through 3D ground penetrating radar. Simulating driving load by kneading to analyze the changes between new and original asphalt pavement permittivity and establish correlation between permittivity and structural depth.