Study on Quantitative Prediction of Pressure in Porous Materials under Dry-Wet Cycles

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14301
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 23020:Architectural environment and building equipment-related
• Research Institution: Kyoto University
• Principal Investigator: Takatori Nobumitsu 京都大学, 工学研究科, 助教 (70880459)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 多孔質材料 / 乾湿風化 / 塩類風化 / 硫酸ナトリウム / 凝灰岩 / ひずみ / 湿気 / 応力

Outline of Final Research Achievements

In this study, we conducted experiments to clarify the relationship between the strain and moisture content of tuff during the moisture absorption process, experiments to clarify the differences in the hydration process of sodium sulfate and its effect on material damage due to water absorption and moisture absorption processes, and a literature review on the current issues on the mechanism of salt weathering. The main results obtained are as follows. The strain generated in the tuff used in this experiment showed a nearly linear relationship between strain and relative humidity in the range of relative humidity above 30%, and strain was more dependent on relative humidity than on water content. The experiments also showed that the difference in crystallization pressure due to sodium sulfate was small due to different wetting processes, and that the same degree of deformation occurred during the moisture absorption and water absorption processes.

Free Research Field

建築環境工学

Academic Significance and Societal Importance of the Research Achievements

建造物や屋外文化財を構成する多孔質材料は、乾湿の繰り返しに伴い材料内の圧力が変化し、材料が変形したり破壊されることがある。これらの現象は乾湿風化あるいは塩類風化と呼ばれ、その抑制方法の確立は文化財保存の分野含め幅広い分野で求められている。一方で、屋外文化財の乾湿風化および塩類風化のメカニズムについては十分な知見が得られているとは言い難い。本研究成果は屋外文化財の乾湿風化および塩類風化のメカニズムを理解する上で、またこれらの風化現象を抑制する方法を模索する上で重要な成果であると考える。