Development of a Numerical Model to Predict the Dielectric Properties of Heterogeneous Asphalt Concrete.

Qingqing Cao,Imad L Al-Qadi

doi:10.3390/s21082643

Abstract

Ground-penetrating radar (GPR) has been used for asphalt concrete (AC) pavement density prediction for the past two decades. Recently, it has been considered as a method for pavement quality control and quality assurance. A numerical method to estimate asphalt pavement specific gravity from its dielectric properties was developed and validated. A three-phase numerical model considering aggregate, binder, and air void components was developed using an AC mixture generation algorithm. A take-and-add algorithm was used to generate the uneven air-void distribution in the three-phase model. The proposed three-phase model is capable of correlating pavement density and bulk and component dielectric properties. The model was validated using field data. Two methods were used to calculate the dielectric constant of the AC mixture, including reflection amplitude and two-way travel time methods. These were simulated and compared when vertical and longitudinal heterogeneity existed within the AC pavement layers. Results indicate that the reflection amplitude method is more sensitive to surface thin layers than the two-way travel time methods. Effect of air-void content, asphalt content, aggregate gradation, and aggregate dielectric constants on the GPR measurements were studied using the numerical model.

Highlights

Ground-penetrating radar (GPR) is a nondestructive testing method widely applied for monitoring and assessing civil structures
For asphalt concrete (AC) pavement density prediction from GPR data, sent and reflected signals from the interface of two materials with different dielectric properties are used in the analysis
The reflection amplitude and two-way travel time (TWTT) methods were usually used to calculate the dielectric constants of pavement

Summary

Introduction

Ground-penetrating radar (GPR) is a nondestructive testing method widely applied for monitoring and assessing civil structures. For asphalt concrete (AC), pavement, density is a key factor that affects pavement performance and service life. It is an important indicator of AC quality control and quality assurance during compaction. For AC pavement density prediction from GPR data, sent and reflected signals from the interface of two materials with different dielectric properties are used in the analysis. The reflection amplitude and two-way travel time (TWTT) methods were usually used to calculate the dielectric constants of pavement. The TWTT method, on the other hand, allows the calculations of the material’s dielectric constant from the average velocity of EM waves in the material. It is usually used to back-calculate a pavement layer’s thickness [28]

Methods

Results

Conclusion