Damage estimation of concrete canal due to freeze and thawed effects by acoustic emission and X-ray CT methods

Abstract

As a detailed inspection of a concrete structure in service, core samples are usually drilled out and then mechanical properties are measured. In this study, damage estimation of freeze-thawed concrete from concrete-core samples is developed, applying acoustic emission (AE) method. By the authors, the quantitative damage evaluation of concrete has been proposed in RILEM TC −212ACD, by applying AE and damage mechanics in the compression test. In this study, characteristics evaluation of cracking damage effects in concrete mechanical properties by detected AE energy in core test. Prior to the compression test, distribution of micro-cracks in a concrete-core sample is inspected by helical X-ray computer tomography (CT). Then, freeze-thawed damaged samples are tested by the compression test with AE monitoring. Concrete-core samples were taken out of a channel structures in Hokkaido, Japan which is extremely developed cracking damage. Thus, it is demonstrated that the concentration of material damage could be evaluated by comparing geometrical characteristics of cracks with the “energy rate” of AE generation, which is analyzed by AE parameter analysis. A relation between AE energy rate, physical properties and geometrical properties of void is correlated, and thus the damage of concrete is qualitatively estimated by AE parameters.