Acoustic Emission Characterization of Corrosion Induced Damage in Reinforced Concrete

Abstract

The deterioration of steel reinforced concrete caused by reinforcing bar corrosion is recognized as a major technical problem in the State of Florida and nationwide. This mode of failure is usually recognized in the final stages when surface cracking and spalling of the concrete occurs. The purpose of this study is to extend work previously reported on a nondestructive monitoring technique to detect, characterize, and locate corrosion induced structural damage. Acoustic emission technology is used to monitor and characterize the deterioration process in a series of controlled laboratory tests. By comparing measured acoustic emission characteristics, including counts and amplitude distributions, with physical examination of test specimens at various phases of corrosion induced damage, a relation between the observed damage and the attendant acoustic emission is developed. The study illustrates the sensitivity of the method to the ongoing deterioration process and explores its use as a corrosion damage monitoring technique. Various aspects of the experimental results are discussed.

Influence of diurnal and seasonal temperature variations on the detection of corrosion in reinforced concrete by acoustic emission

“…Moreover, the control emitted virtually zero emissions over the entire test duration (~120 hours) strongly suggesting that the emissions from Beams 1-3 are as a result of corrosion as opposed to other mechanisms such as thermally induced AE or water loss. The clear distinction between the corroding beams and the control supports Dunn et al [26] who found that AE could distinguish between noble and active specimens.…”

“…Li and Shah [23] successfully used AE on concrete under going uniaxial tensile tests, where the cause of emission was the nucleation of microcracks. Whilst AE has been used as a method to monitor the structural integrity of beams placed under increasing loads with various levels of corrosion induced damage [24,25], AE has also been applied to the detection of steel reinforcement corrosion [26][27][28][29].…”

Cover zone properties influencing acoustic emission due to corrosion

“…9(b). Comparable behaviour was reported by Dunn et al [12] who considered this a characteristic of periods of crack extension followed by continued corrosion. They believed that once the void provided by a previous crack was filled by new corrosion products, additional cracking then followed.…”

“…The number of hits over time is often used in AE analysis [10][11][12][13]18], however, whilst this is often used to assess the rate of activity of a sample over time, the data is non- A summary of the key data is presented in Table 3, listing the total hits, ABS energy, Table 3 as no corrosion products were found. The results hereon in have been divided into three areas to describe the effects of strength, cover depth and rebar diameter.…”

“…It has been found that AE is very sensitive to growth and initiation of cracks in concrete structures [9]. The use of AE as a method to detect corrosion of steel is well documented [10][11][12][13][14]. AE is not an electrochemical method, but by utilising the sensitivity of the technique to the growth and initiation of microcracks AE is able to identify corrosion by detecting microcracking induced to concrete as a consequence of the corrosion reaction [10].…”