Elucidating the mechanism of concrete void closure by silica gel: repair materials open the way to the deep sea.

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K18828
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 22:Civil engineering and related fields
• Research Institution: Nagoya Institute of Technology
• Principal Investigator: Yoshida Ryo 名古屋工業大学, 工学(系)研究科(研究院), 准教授 (40548575)
• Project Period (FY): 2022-06-30 – 2024-03-31
• Keywords: ケイ酸 / ゲル / 止水 / 補修 / 劣化 / 含浸 / コンクリート / 空隙

Outline of Final Research Achievements

The applicant's research on silicate surface impregnation materials (repair materials) confirmed a high resistance to moisture penetration, which was not originally expected, when the conventional process was omitted (Patent Application 2020-190615). In this study, it was hypothesised that silicate aggregates (gels) are formed in the concrete voids and that the voids are blocked by the water absorption and swelling of the gels, thereby inhibiting water penetration,
Subject 1: The mechanism of silica gel formation in the voids (hypothesis) was verified, and Subject 2: A new repair concept was created in which the swelling action of silica gel formed in the voids of concrete stops the penetration of rainwater and seawater, which can cause corrosion of steel bars (Patent Application 2023-138819).

Free Research Field

コンクリート工学

Academic Significance and Societal Importance of the Research Achievements

コンクリート標準示方書の耐久性照査は、点検負担の大きい中性化から、水分浸透に基づいた鉄筋腐食へと転換しつつある。この転換には、照査体系の整備に加え、水分浸透を抑制する補修材の開発が必要不可欠である。本研究では、これまでの補修材の施工不良メカニズムの解明とともに、そのメカニズムを水分浸透抑制に利用し、鉄筋コンクリートの劣化因子である二酸化炭素、塩分、酸性雨との接触によりバリア機能を発現する「毒を以て毒を制す」新たな補修コンセプトを提案した。