Evaluation of Delamination in Concrete by IE Testing Using Multi-Channel Elastic Wave Data.

Seong-Hoon Kee,Jin-Wook Lee,Ma Doreen Candelaria

doi:10.3390/s20010201

Seong-Hoon Kee, Jin-Wook Lee + Show 1 more

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https://doi.org/10.3390/s20010201

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Abstract

The main objectives of this study are to develop a non-destructive test method for evaluating delamination defects in concrete by the Impact-echo test using multi-channel elastic wave data and to verify the validity of the proposed method by experimental studies in the laboratory. First, prototype equipment using an eight-channel linear sensor array was developed to perform elastic wave measurements on the surface of the concrete. In this study, three concrete slab specimens (1500 mm (width) by 1500 mm (length) by 300 mm (thickness)), with simulated delamination defects of various lateral dimensions and depth, were designed and constructed in the laboratory. Multi-channel elastic wave signals measured on the three concrete specimens were converted to the frequency-phase velocity image by using the phase-shift method. A data processing method was proposed to extract the dominant propagating waves and non-propagating waves from the dispersion images. The dominant wave modes were used to evaluate delamination defects in concrete. It was demonstrated that the surface wave velocity values were useful for characterizing the shallow delamination defects in concrete. In addition, the peak frequency of non-propagating wave modes extracted from the dispersion images gives information on the lateral dimensions and depths of the delamination defects. This study also discussed the feasibility of combined use of the results from propagating and non-propagating wave modes to better understand the information on delamination defects in concrete. As will be discussed, the multi-channel elastic wave measurements enable more accurate, consistent, and rapid measurements and data processing for evaluation of delamination defects in concrete than the single-channel sensing method.

Highlights

A delamination defect in concrete is a subsurface fracture plane that is caused by corrosion of embedded reinforcing steels in concrete (Figure 1b,c)
Various durability issues could arise by increasing moisture and/or deleterious materials in concrete, which could accelerate the corrosion and other deterioration mechanisms
The locations the withdispersion previous image observation was observed thatwas thenot size of delamination has a of great sensor array and impact source used to obtain the results shown in Figure were presented as white influence on the estimation error of the depth of delamination defects using the analysis of the S1 solid and squares, in A

Summary

Introduction

A delamination defect in concrete is a subsurface fracture plane that is caused by corrosion of embedded reinforcing steels in concrete (Figure 1b,c). The presence of delamination defects in concrete elements may not necessarily imply structural failure of reinforced concrete elements. Various durability issues could arise by increasing moisture and/or deleterious materials in concrete, which could accelerate the corrosion and other deterioration mechanisms (i.e., freeze-thaw damage and carbonation). Delamination defects in concrete with continuous corrosion can progress to open spalls and eventually degrade the structural integrity of reinforced concrete elements. Delamination defects in plate-like concrete elements in buildings and infrastructure systems (e.g., slabs in buildings, concrete bridge decks, and continuous concrete pavement) could critically affect the durability and/or structural integrity of concrete elements, which could threaten public users’ safety. Infrastructure management agencies in many countries have dedicated a great

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