Development of In-Situ Nondestructive Evaluation (NDE) Techniques for Rebar Corrosion, Concrete Deterioration and Internal Cracks

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Title: Development of In-Situ Nondestructive Evaluation (NDE) Techniques for Rebar Corrosion, Concrete Deterioration and Internal Cracks

Author(s): M. Ohtsu and K. Yuno

Publication: Special Publication

Volume: 128

Issue:

Appears on pages(s): 893-908

Keywords: Acoustics; compression tests; corrosion; cracking (fracturing;); deterioration; microcracking; nondestructive tests; reinforcing steels; spectroscopy; ultrasonic tests

Date: 11/1/1991

Abstract:
In situ nondestructive evaluation techniques for estimating rebar corrosion, crack depth, deterioration due to microfracturing, and kinematics of crack nucleation in concrete structures are investigated. For corrosion monitoring, a half-cell potential technique is improved. Distribution of electrical potential on rebar surface is analytically determined from surface observation of concrete, based on a computer-aided CSM (charge simulation method) procedure. The depth of surface crack is evaluated by the ultrasonic spectroscopy. A reference curve determined from the ratio of peak frequencies is applicable to not only plain concrete but also reinforced concrete (RC) members. The amount of microcracks associated with the deterio-ration is estimated from AE (acoustic emission) activity during a uniaxial compression test of core sample. The occurrence of AE events is quantitatively analyzed on the basis of the rate process theory. A source inversion analysis of AE waveform is developed to obtain information on location, type, and orienta- ion of crack nucleation. Basic results of the above techniques are summarized and in situ applications are discussed.