Study of Frost Weathering Mechanism of Porous Materials and its Protective Measures.
| Project/Area Number |
09650615
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Building structures/materials
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| Research Institution | Tokyo National Research Institute of Cultural Properties |
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Principal Investigator |
ISHIZAKI Takeshi Tokyo National Research of Cultural Properties, Head of Physics Section, 保存科学部・物理研究室, 室長 (80212877)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1998: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1997: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Stone monuments / Brick buildings / Frost weathering / Frost heave / Ice segregation / Oya tuff / Salt weathering / Salt fluorescence / 水晶析出 / レンガ |
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| Research Abstract |
1) The brick buildings and stone monuments in cold regions deteriorate due to freezing and melting cycles. The field survey on the frost damages of brick chimney of Asahikawa Kaiko-sha in Hokkaido Prefecture and brick chimney of Ynaizu in Fukushima Prefecture revealed that the water supply was important factor for frost damage. The numerical technique to calculate water content distribution and water flow in brick buildings and stone monuments was developed, This technique is also applicable to the calculation of the water and solute transport related to salt weathering in the brick monuments in dry regions.
2) The basic mechanism of frost weathering is frost heave phenomenon. During the freezing of porous material, water is induced to flow to the freezing front and segregates as lenses. In order to clarify the frost heave mechanism, frost heaving experiments were performed using glass beads of different diameter under different temperature conditions. The experimental results gave the
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relationship between the ice segregation rates and temperature conditions, The experimental results were compared with the frost heave model based on the crystal growth theory. These results were reported in the International Symposium and published in journals.
3) The porous materials of stone monuments , such as Oya tuff break when the frost heave pressure exceeds their tensile strength. The laboratory experiments were carried out to investigate the ice segregation process under the different temperature conditions by using microscope and video recorder system. The frost heave model for this process was proposed and compared with the experimental results. The calculated results corresponded well with the experimental results. These results were presented at the International Symposium.
4) The salt weathering is observed for stone monuments in Oita Prefecture. The salt weathering is caused by the salt crystallization process near the surface during the water evaporates from the surface. This physical process is similar to the frost weathering, The material transport is expressed by similar differential equations. Because of these similarities, I would like to widen my study topic related to frost weathering to salt weathering which can be seen in historical sites in Asian countries. Less
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Report
(3 results)
Research Products
(12 results)
