Abstract
The X ray CT test is one of the most useful method for detection and visualization of cracking damage of concrete. In recent years, damage evaluation of in-situ concrete structures is now in urgent demand. By the authors, quantitative damage estimation of concrete is proposed to be performed, applying acoustic emission (AE) measurement in a uniaxial compression test with X-ray CT test. In this study, crack concentration properties of concrete samples is quantitatively analyzed, based on X ray CT images with the spatial statistics, because notable discrepancy of spatial statistics parameters are observed between damaged concrete and undamaged concrete. The concrete damage is quantitatively defined as decrease of mechanical characteristics, such as compressive strength and Young's modulus. Correlating concentration index with the damage parameter, quantitative estimation of damage is proposed in terms of the parameter ‘Cδ’. Concrete core samples were taken from reinforced concrete columns of an existing canal which is strongly affected by freeze and thawed process. Prior to the mechanical test, distribution of micro-cracks in a concrete-core sample was inspected by helical X-ray CT, which scans at one-millimeter intervals. Thus, the results suggest that the damage of concrete could be quantitatively evaluated by X-ray CT images. A relation between X-ray CT images and damage parameters is correlated, and the damage of concrete is quantitatively estimated using X-ray CT parameter with spatial statistics.
