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Following the initiation of corrosion in reinforcement, expansion of corrosion products generates corrosion-induced cracks in concrete. At the meso-scale, accumulation and coalescence of micro-cracks create the fracture process zone. Since nucleation of an individual micro-crack can be detected by acoustic emission (AE) techniques, the moment tensor analysis of AE waves is applied to quantitatively identify cracking kinematics of a location, a crack-type and a crack orientation. At the macro-scale, initiation and extension of the corrosion-induced cracks are analyzed by means of classical fracture mechanics, applying the boundary element method (BEM). The generation of corrosion-induced cracks was simulated in expansion tests on concrete specimens. Kinematical mechanisms of micro-cracks were identified by the SiGMA (Simplified Green's functions for Moment tensor Analysis) analysis. By applying the two-domain BEM analysis, extension of the corrosion-induced crack in an arbitrary direction was analyzed. With respect to the orientations of crack extension, results of the BEM analysis were compared with those of the SiGMA analysis, introducing the normalized stress intensity factors. It is demonstrated that extension of the corrosion-induced crack is governed by the mode-I failure both at the meso-scale and at the macro-scale.

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Nucleation of micro-cracking due to corrosion is detected and analyzed by AE-SiGMA procedure, by which crack kinematics of locations, types and orientations are quantitatively determined. Since these kinematical outcomes are obtained as three-dimensional (3-D) locations and vectors, 3-D visualization is developed by using VRML (Virtual Reality Modeling Language). The procedure is applied to corrosion cracking. Kinematics of micro-cracking due to corrosion are studied by numerical analysis BEM. Thus, relations between the stress intensity factors and cracking modes are investigated for different crack-patterns. It is confirmed that micromechanics of corrosion cracking are dominantly of mode-I failure associate with mixed-mode and mode-II.