Development of a Simulation-Based Approach for Cold In-Place Recycled Pavement Moisture-Content Prediction Using Ground-Penetrating Radar

Abstract

Ground-penetrating radar (GPR) recently has been used for quality control and quality assurance of the asphalt concrete (AC) pavement-construction process. The objective of this study was to investigate the feasibility of estimating, by using GPR, the moisture content in AC pavement. This application is particularly important for emulsion-stabilized cold in-place recycling (CIR) and cold central-plant recycling (CCPR), where monitoring the moisture content is necessary for deciding the timing of opening the road to traffic, overlay placement, or both. Four field tests were performed using GPR on CIR- or CCPR-treated AC pavement. A numerical simulation model of AC pavement with internal moisture was generated using the information from mix design, and virtual GPR tests were performed using the finite-difference time-domain (FDTD) method. After calibration, a moisture-prediction formula derived from the simulation model was used to correlate the dielectric constant predicted by GPR to the moisture content within cold recycled layers. The GPR signal was “denoised” by improving its stability and mitigating the measured-height mismatch. The in-situ moisture content was predicted using the proposed method and compared with field-collected samples. Results showed that the proposed method is effective in estimating CIR- and CCPR-layer moisture content. The variation of dielectric constants in field tests is also discussed. A testing protocol for predicting moisture content using GPR is suggested for CIR and CCPR pavement.

An Analytical Antenna Modeling of Electromagnetic Wave Propagation in Inhomogeneous Media Using FDTD: A Comprehensive Study

“…The charge density (ρ v ) and the current density (J) describe the distribution of the charge and current within the medium. To study a free-source medium, we can apply the curl operator to both sides of Equation (3).…”

“…Ground-penetrating radar (GPR) is a non-destructive investigative tool that uses electromagnetic (EM) waves and is commonly utilized in the fields of geophysics, structures, and transport systems [1][2][3]. However, the complexity of GPR data, which are based on EM waves, presents a challenge for the users attempting to interpret them.…”

“…Recent advancements in high-performance computing technology have made EM wave simulations increasingly useful within various fields. As a result, EM wave modeling is rapidly increasing in popularity, and the quality of GPR models is becoming more realistic [1,3].…”

“…This experimental validation could be improved by using the same antenna frequency that was used in the numerical analysis. Another recent study [3] used 3D modeling to simulate the behavior of concrete pavement with a random distribution, but for the computational efficiency, it only utilized the 2D slice of the 3D model. Additionally, the study used a transmitter and receiver as the sources for the EM wave simulation, which is not representative of commercial antennas.…”