Inspection of Concrete Bridge Decks With Asphalt Overlays — a Comparison of Nondestructive Evaluation Methods

Cost effective bridge deck rehabilitation makes it necessary to locate the areas in need of repair to accurately estimate the quantity of deteriorated concrete. Since the bituminous overlay prevents visual identification of these areas, nondestructive testing and evaluation techniques are essential [1]. Conventional nondestructive testing techniques, such as sounding by hammer and chain drag, do not fare well on asphalt covered decks, primarily due to the inefficient coupling of energy between the asphalt overlay and the concrete. They are usually effective only after the asphalt overlay has been removed [2]. Destructive testing methods such as core samples are effective when a large number of random samples are obtained, which is both costly and unnecessarily damaging to the bridge deck. Recently, nondestructive testing and evaluation techniques, such as impact-echo [3–9], ground penetrating radar [10–17], and infrared thermography [18–23], have shown promise for the noninvasive evaluation of the damage accumulation in concrete bridge decks overlaid with asphalt concrete wearing surfaces. Each nondestructive evaluation method has its own current advantages and limitations which are presented and discussed in this study.</p