The Use of Ground Penetrating Radar, Thermal Camera and Laser Scanner Technology in Asphalt Crack Detection and Diagnostics

Abstract

The amount and types of pavement distress have been one of the main indicators for the pavement quality in most of the pavement management systems. However, existing commercial techniques for locating these distresses and evaluating their severity have proven to be insufficiently reliable. Over the last few years new technologies have been developed and tested to provide more accurate and repeatable pavement distress mapping results.

This paper presents a summary of authors’ experiences with three relatively new technologies which have provided very promising results in pavement distress surveys. All three techniques, ground penetrating radar (GPR), thermal camera and laser scanner are based on longer electromagnetic wavelengths than visual light and thus their advantage is detection of cracks inside the pavement that cannot be seen by human eyes. Over the last few years these techniques have become both fast and accurate enough to make them viable as field survey tools and at the same time improvements in data processing and storage capabilities have enabled the use of these techniques.

Ground penetrating radar has traditionally been used to measure pavement thickness but the data can also be used to evaluate pavement quality. Three dimensional GPR imaging has provided new interesting information about the formation of transverse and longitudinal cracks especially at the sites where pavement thickness varies substantially in transverse directions. Dielectric value analysis using different antenna frequencies has also proven to work well in detecting salt related cracking in asphalt. Analysis of amplitudes and frequency response analysis can also be used to detect moisture related problems in asphalt. Additionally, segregation can be detected with GPR.

The recent results from testing high precision and fast thermal cameras have provided interesting new possibilities in detecting pavement distress. Top down cracking, for instance, seems to generate slightly beneath the pavement surface and these cracks can be seen with thermal cameras before they become visible to the human eye. Thermal camera analysis also shows the effect of water pumping through the pavement due to heavy vehicle loading.

Finally this paper presents the latest results from emission analysis of laser scanner data to detect different types of pavement distress.