Meso-damage evolution analysis of magnesium oxychloride cement concrete based on X-CT and grey-level co-occurrence matrix

Abstract

X-CT technology can be used to analyse the internal damage to concrete due to rust expansion. However, the original X-CT slice of the internal damage of the concrete can only be used to quantitatively analyse the internal damage in the specimen. The X-CT pictures of the concrete cannot deeply excavate the slight changes in the concrete specimens before and after damage due to rust expansion. As a texture feature analysis method, grey-level co-occurrence matrices (GLCM) have the ability to deeply mine the subtle grey-scale changes of original X-CT pictures. Therefore, this paper coupled X-CT and GLCM to analyse the internal damage in magnesium oxychloride cement concrete due to rust expansion. The four characteristic values of GLCM—contrast, correlation, energy and homogeneity—are used to reflect the internal concrete damage’s evolution. The results show that there is a significant exponential relationship between the surface crack formation and the internal volume growth of the specimen. The contrast value gradually increases during the concrete damage process, while the correlation, energy and homogeneity values gradually decrease during this process, and these four eigenvalues all follow the normal distribution. By using these four characteristic values to analyse the reliability of concrete specimens, it is concluded that homogeneity can be better used to evaluate the internal damage of concrete specimens. The peak bandwidth of matrix in a color heat map decreases gradually and extends along the main diagonal of the matrix in the process of specimen damage that can be used to accurately reflect the damage to the concrete due to the rust expansion force.