Development of damage parameter for concrete by using acoustic emission and X ray computed tomography

As a detailed inspection of a concrete structure in service, core samples are usually drilled out and then physical properties are measured. In this study, damage estimation of structural concrete from concrete-core samples is developed, applying acoustic emission (AE) and X-ray CT methods. By the authors, the quantitative damage evaluation of concrete has been proposed in RILEM TC-212ACD, by applying AE energy parameter and damage mechanics in the compression test. In this study, detection of cracking damage in concrete 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 samples are tested by the compression test with AE measurement. Concrete-core samples were taken out of a head works in Hokkaido, Japan which is extremely developed inner 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 and damage parameters is correlated, and thus the damage of concrete is qualitatively estimated.