2020 Fiscal Year Final Research Report
Elucidation of the effect of surface charge on mass transport properties for reliable prediction of salt weathering in historic brick buildings
| Project/Area Number |
19K23565
|
|---|
| Research Category |
Grant-in-Aid for Research Activity Start-up
|
| Allocation Type | Multi-year Fund |
|---|
| Review Section |
0304:Architecture, building engineering, and related fields
|
|---|
| Research Institution | Independent Administrative Institution National Institutes for Cultural Heritage Tokyo National Research Institute for Cultural Properties |
|---|
Principal Investigator |
Mizutani Etsuko 独立行政法人国立文化財機構東京文化財研究所, 保存科学研究センター, 研究員 (90849796)
|
|---|
| Project Period (FY) |
2019-08-30 – 2021-03-31
|
| Keywords | 塩類風化 / 表面電荷 / 水分拡散係数 / 画像解析 / ３DMA / ゼータ電位 / Ｘ線CT / 電粘性効果 |
|---|
| Outline of Final Research Achievements |
The effect of the surface charge and the changes in pore structure due to salt precipitation in the fired clay bricks on mass transport properties were quantitatively examined to develop a reliable prediction model for salt weathering.
Two kinds of Japanese bricks negatively charged were used for the experiments. Salt solution uptake rates were revealed to be drastically slower than that assumed by characteristics of bulk solution. Three-dimensional scanning by synchrotron X-ray computed tomography was conducted to quantify the time change in salt crystal distribution during drying. Additionally, the pore size distribution, tortuosity and effective porosity and specific surface area before and after salt precipitation were calculated by the 3D medial axis (3DMA) processing with segmented images to investigate the change of saturated hydraulic conductivity and vapour diffusivity due to salt precipitation.
|
| Free Research Field |
環境工学, 文化財保存科学
|
| Academic Significance and Societal Importance of the Research Achievements |
塩類風化の予測モデルの開発に向けては、多孔質材料中での塩類輸送や塩析出性状を定量的に示すことの難しさから、考慮すべき現象の把握や妥当性の検証が困難であることが問題である。本研究ではガンマ線減衰法や放射光X線CTといった非破壊分析手法の利用や画像解析の工夫により焼成煉瓦の表面電気的特性と塩析出に伴う空隙構造変化が塩溶液と水蒸気の移動特性に与える影響を定量的に評価し、これにより輸送性状に影響を及ぼす諸要因が検討可能になった。また表面電荷が毛管圧による溶液の輸送に影響を及ぼすことを示唆する結果を得たことは、数値解析モデルの開発のみならず実建造物の保存処置方法を検討するうえでも重要な知見である。
|
