Detection and]identification of concrete cracking in reinforced concrete by acoustic emission

Cracking in concrete due to corrosion of rebars in reinforced concrete is one of critical problems To clarify cracking process, acoustic emission (AE) measurement is applied. In an accelerated corrosion test, AE events are detected and monitored continuously Comparing with permeation of chloride ions, it is found that onset of corrosion and nucleation of cracking can be qualified from AE activity Applying SiGMA procedure nucleation mechanisms of cracks due to expansion of corrosive product are identified. During extension of the surface crack, tensile cracks ate nucleated dominantly For the spalling crack, both he tensile and the shear cracks are generated as the former dominates the latter approaching to a stress-free surface. In contrast, it is found that the internal crack is nucleated mainly due to shear-crack motion.