Acquisition of comprehensive knowledge regarding surface quality and durability for achieving rational durability design of concrete structure

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K14803
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 22010:Civil engineering material, execution and construction management-related
• Research Institution: Ehime University (2023); Hiroshima University (2020)
• Principal Investigator: Yuki YOKOYAMA 愛媛大学, 理工学研究科(工学系), 助教 (00847080)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: コンクリート / 耐久性 / 表層品質 / 透気性 / 強度 / 中性化

Outline of Final Research Achievements

In this study, the correlation between the surface air permeability coefficient, which serves as an evaluation index for the quality of the surface layer of concrete, and the rebound index, which serves as an evaluation index for the strength of the surface was analyzed. As a result, a correlation between the surface air permeability coefficient and the rebound index was confirmed. Furthermore, in cases where there is no influence of rainfall, the correlation tends to increase at earlier ages compared to those with rainfall influence. The correlation between the rebound index and the neutralization rate coefficient was also analyzed. Within the first few years of material age, carbonation progresses at a constant rate, but after several decades, a phenomenon where neutralization progress stagnates was observed. The timing of carbonation stagnation varies depending on the presence or absence of rebound and rainfall influence.

Free Research Field

コンクリート工学

Academic Significance and Societal Importance of the Research Achievements

鉄筋コンクリート構造物の劣化因子である液状水や二酸化炭素，塩化物イオンはコンクリートの表層部から内部へ浸透する．ゆえにコンクリート表層部の品質は耐久性を確保するために重要である．既往の研究により，表層部の透気性と強度の間には強い相関は見られなかったが，本研究を通じ，材齢の経過に伴い透気性と強度の間の相関が向上するとともに，降雨の影響の有無が相関関係に影響を及ぼすことが明らかとなった．本現象は当該分野の従来の常識とは異なる傾向を示すため，耐久性を適切に評価及び確保するためには本現象を深く理解することは極めて重要であると考えられる．