An overview of GPR applications for evaluation of pavement thickness and cracking

Pavement asset management requires accurate and rapid measurement of asphalt layer thickness for reliable backcalculation of modulus values of pavement layers from nondestructive deflection tests. Also needed are measurements of layer delamination, surface cracking, and other distresses. Top-down cracking in the longitudinal wheel path of thick asphalt highway pavement is a major distress problem. The objective of this paper is to evaluate several nondestructive testing technologies that can be operated at highway speed to assess asphalt thickness and surface cracking depth. This paper presents key findings of an extensive literature review of GPR equipment and data interpretation methodologies. The study supports that nondestructive GPR technology has evolved over the last three decades to measure pavement layer thickness and delamination accurately, which is more cost-effective than extracting cores. The study did not find a field technology that can operate at highway speeds for mapping pavement surface cracking and its penetration depth. However, GPR remote sensing has the potential to map the penetration depth of top-down cracking from the surface through asphalt layer thickness.

I. Introduction

In the United States and most European countries most of the public investments are allocated to preserve and maintain the surface transportation infrastructure assets such as highways and bridges. Aging and high volumes of traffic generally accelerate damage to pavements. Highway asset management by most highway agencies requires the evaluation and maintenance of pavements using reliable nondestructive test (NDT) methods at highway speeds. Several NDT methods have been applied to pavements during the past four decades. These include: deflection testing, thermal infrared imaging, and seismic and geophysical methods. This paper discusses these methods.