Corrosion mechanisms in reinforced concrete by acoustic emission

Continuous acoustic emission (AE) monitoring is applied to a cyclic wet and dry test of reinforced concrete beams. The onset of corrosion and the nucleation of corrosion-induced cracks in concrete are successfully identified, and then, cross-sections inside the concrete specimen are observed by an electron probe micro analyzer (EPMA). Results of AE parameter analysis are compared with the corrosion mechanisms observed by EPMA. Further, a relation between kinematical information of AE sources and nucleation of micro-cracks inside is identified by the SiGMA analysis and observed by the stereo-microscope. From these results, AE is a promising technique to quantitatively evaluate the corrosion process in concrete due to expansion of corrosion products at an early stage is demonstrated.