Combining Portable Falling Weight Deflectometer and Surface Wave Measurements for Evaluation of Longitudinal Joints in Asphalt Pavements

Abstract

Longitudinal joints in asphalt pavements typically have lower densities than the interior portion of the mat. Therefore, they tend to exhibit surface distresses such as cracking and raveling more rapidly. The objective of this study is to evaluate the ability of nondestructive testing (NDT) for assessing the relative condition of a longitudinal joint. NDT has been significantly developed for pavement evaluation during the past decade. Deflection and surface wave methods are the most commonly used for pavement evaluation. The portable falling weight deflectometer (PFWD) is increasingly used in quality control and quality assurance to provide rapid determination of the equivalent surface elastic modulus. However, the multichannel analysis of the surface waves (MASW) method consists of using ultrasonic transducers to measure surface waves traveling through the pavement and invert for the elastic modulus of different layers. This study presents results from both deflection and seismic methods to assess the quality of longitudinal joints. Both methods are performed at the same locations of the centerline of a test track. Pavement deflection is also measured on the wheelpath for comparison with previous data. Across the joint, changes smaller than 7% were observed in deflection values. These preliminary results cannot be directly related to joint quality because the contribution of sublayers to the modulus measured with the PFWD needs to be estimated. MASW measurements showed promising results for evaluating the attenuation of surface waves due to the joint. Further work is required to improve the coupling between the transducers and asphalt surface.