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Study on obtaining quantitative index to evaluate durability of cover concrete



Author(s): Isao Ujike, Shinichiro Okazaki
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: 1558- 1566
Total Pages: 8
Language: English


Abstract: 
To perform appropriate preventative maintenance of the concrete structure, the structure should be inspected to identify the deterioration mechanism with the possibility from the inspection result and predict the deterioration progress. The in-site air permeability test is proposed as one of the surveying techniques in the inspection process. The air permeability test can be conducted in a short time using a compact apparatus. The tightness of cover concrete is quantitatively evaluated by the air permeability coefficient. However, the moisture content in concrete must be considered when evaluating concrete quality by the air permeability coefficient, because the air permeability coefficient is highly influenced by the internal pore structure of and moisture content in concrete. In addition, the durability of cover concrete is generally assessed by grading it as “excellent, normal, or poor”. Moreover, the air permeability coefficient cannot be used directly to predict deterioration.

This study proposes a new in-site air permeability test, which is characterized as follows. The air permeability coefficient is calculated from the measured results. The area in cover concrete being measured is clear. The distribution of the air permeability coefficient in the direction of the depth from the concrete surface is appropriate. This study focuses on reinforcement corrosion due to chloride attacks, which is one of the degradation phenomena experienced by concrete structures. The complementary lines that indicate the apparent diffusion coefficient of chloride ions are incorporated into the relationship between the air permeability coefficient and the moisture content. The index used to quantitatively evaluate the durability of the concrete structure can be obtained from the air permeability test results referring to the complementary lines. The relationship between the air permeability coefficient and the moisture content is obtained from in-site measurements of real structures. The applicability of the proposed technique is investigated using the results of the air permeability coefficient obtained by the new in-site test and the moisture content measured with real structures.


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