Comparison of NDT Methods for Assessment of a Concrete Bridge Deck

TLDR

The study evaluates the field application of three nondestructive tests—air‑coupled impact echo, infrared thermography, and chain‑drag sounding—on an in‑service concrete bridge deck. Two contactless impact‑echo systems produced two‑dimensional frequency maps, while infrared thermography and chain‑drag tests generated temperature and result maps, respectively, and eight core samples verified near‑surface delamination locations; the methods were then compared on accuracy, practicality, and cost. All three NDT methods agreed well with core samples in locating shallow delamination, and the chain‑drag method was not more accurate or reliable than the others.

Abstract

The field application of three different nondestructive tests (NDTs)—air-coupled impact echo (IE), infrared (IR) thermography, and sounding (chain drag)—are evaluated in this paper, where an actual in-service concrete bridge deck is tested. Two different contactless IE test equipment sets are deployed as part of an effort to develop new rapid measurement methods. The IE data are presented as two-dimensional frequency maps, and the IR data are presented as temperature maps over the tested area. Sounding (chain-drag) result maps are also presented. For verification of the location of near-surface delamination damage, eight drilled core samples were extracted from the test area. The results obtained from each of the individual NDT methods show reasonably good agreement with the drilled cores in terms of locating near-surface delamination. Finally, the NDT methods are compared across general performance criteria, considering accuracy, testing practicality, and costs. The analysis shows that all of the evaluated NDT methods are comparable, and the chain-drag method is not more accurate and reliable for detection of shallow delamination in the deck.