Quantitative evaluation of freezing-thawing damage in plain concrete by digital-image-processing technique

Author(s): Shuguang Li, Gaixin Chen, Yihui Lu
Paper category: Conference
Book title: 2nd International conference on Microstructural-related Durability of Cementitious Composites
Editor(s): Guang Ye, K. Van Breugel, Wei Sun, Changwen Miao
Print ISBN: 978-2-35158-129-2
e-ISBN: 978-2-35158-123-0
Publisher: RILEM Publications SARL
Pages: 1156 - 1164
Total Pages: 8
Language: English

Most of the concrete structures in North China are subjected to freezing and thawing (FT) damage. The general damage evaluation parameters for freezing-thawing, such as resonant frequency , ultrasonic wave velocity and CT number obtained by by x-ray computerized tomography are all phenomenological descriptions and cannot reveal the essence of the damage, which is the initiation and propagation of microcracks in concrete. This paper proposes a method of evaluating FT damage of concrete by quantitative microcrack analysis based on digital-image-processing techniques. A vacuum fluorescent-epoxy impregnation technique is used to highlight microcracks in the concrete matrix. A MATLAB-based software package called QASMC (Quantitative Analysis System of Microcracks in Concrete) which includes the image-binarizing module, shape-analyzing module, crack-skeletonizing module and automatic measuring module is developed to automatically extract and analyze the microcrack patterns. Six microcrack characteristics namely total length, length density (total length per observing area), total area, area density (ratio of microcrack area to observing area), maximum width and average width in slices from the plain concrete specimens deteriorated by different freezing and thawing cycles are obtained using QASMC. Results show that the first five parameters are all increasing with the increase of freezing and thawing cycles. Correlations between the mechanical properties such as the relative flexural strength, relative tensile strength and FT damage degree and the microcrack density (length density and area density) are established and it is shown that both the relative flexural strength and the tensile strength decrease with the increase of the microcrack density, while the FT damage degree increases linearly with the increase of the microcrack density. The results demonstrate that quantitative microcrack analysis is effective in quantifying the freezing-thawing damage of concrete and can be used as an important and promising tool in diagnosis of deteriorated concrete structures.

Online publication: 2013
Publication Type: full_text
Public price (Euros): 0.00