Research activity information

• Mar. 2024 前田記念工学振興財団, 令和６年度山田一宇賞


• Jun. 2023 13th Nordic Symposium on Building Physics, Best Paper Award, Water uptake of porous building materials with extremely small air entrapment effects

  Kazuma Fukui, Satoru Takada

  共同研究・競争的資金等の業績IDIRI


• Nov. 2021 日本建築学会環境工学委員会, 2021年度日本建築学会大会（東海）学術講演会 環境工学部門 若手優秀発表賞


• Aug. 2018 日本建築学会近畿支部, 平成30年度日本建築学会近畿支部研究発表会 優秀発表賞


• Jul. 2018 京都大学大学院工学研究科, 工学研究科馬詰研究奨励賞


• Aug. 2017 日本建築学会近畿支部, 平成29年度日本建築学会近畿支部研究発表会 優秀発表賞


• Nov. 2016 日本建築学会近畿支部 環境工学部会, 建築環境工学若手研究者研究発表・交流会 プレゼン賞

• Study on mold and condensation risks after vacancy of residential space with walls in contact with the ground

  Lu Yuan, Satoru Takada, Kazuma Fukui

  Apr. 2024, Journal of Building Engineering

  [Refereed]

  Scientific journal


• Impact of air entrapment on capillary absorption in porous building materials

  Kazuma Fukui, Satoru Takada

  Mar. 2024, Journal of Building Physics

  [Refereed][Invited]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Water transfer in building materials over capillary saturation during freezing

  Kazuma Fukui, Satoru Takada

  Mar. 2024, Cold Regions Science and Technology, English

  [Refereed]

  Scientific journal


• Development of pore water pressure during freeze-thaw cycles in weather conditions

  Kazuma Fukui, Chiemi Iba

  Elsevier {BV}, Jan. 2024, Cold Regions Science and Technology, 217, 104044 - 104044, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Water uptake of porous building materials with extremely small air entrapment effects

  Kazuma Fukui, Satoru Takada

  Abstract When a porous material is near capillary saturation, entrapped air is expected to affect water transfer through the pores. Based on the results of water absorption tests at reduced air pressure, Janssen et al. (Energy Procedia, 2015) demonstrated that air entrapment prevents water absorption above capillary saturation. In this study, to understand the air entrapment effects on water transfer in the high-water-saturation region, we further examined the water transfer characteristics corresponding to extremely small air entrapment effects. First, using three common porous building materials, water uptake experiments were conducted at low air pressure near vacuum (several kilopascals), and the time evolution of the water absorption was measured. The results show that low air pressure accelerates water uptake by brick and aerated concrete specimens, whereas the water uptake by calcium silicate board specimens is not significantly affected. These differences among the materials are discussed from the viewpoint of the pore structure. Furthermore, the results of simultaneous water and air transfer calculations confirm that air entrapment and pressure development in the pores can significantly reduce the rate of water uptake and the water content that a material can reach after capillary absorption.

  Lead, Dec. 2023, Journal of Physics: Conference Series

  [Refereed]

  International conference proceedings

  Link to Kobe Univ. Repository (Kernel)


• Potential errors and improvements in estimating the humidity dependency of vapor permeability using average humidity during cup tests

  Kazuma Fukui, Satoru Takada

  Elsevier BV, Jul. 2023, Journal of Building Engineering, 71, 106578 - 106578

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Quantification of moisture flux from the wall surface in contact with the ground in a semi-underground space based on measurements and hygrothermal analysis

  Lu Yuan, Satoru Takada, Yota Nagano, Kazuma Fukui

  Elsevier BV, May 2023, Journal of Building Engineering, 73, 106803 - 106803

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Deterioration mechanism and hygrothermal condition of tuff stones used for exteriors at former Koshien Hotel

  Chiemi Iba, Tomoko Uno, Koki Yamada, Kazuma Fukui, Daisuke Ogura

  May 2023, Journal of Cultural Heritage

  [Refereed]

  Scientific journal


• Coupled hygrothermal and mechanical simulations of highly anisotropic building material during freezing and thawing

  Kazuma Fukui, Chiemi Iba, Daisuke Ogura

  Apr. 2023, Journal of Building Physics

  [Refereed][Invited]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Study on efficient and accurate protocols of measuring sorption isotherm of porous building materials using three-dimensional hygrothermal simulation

  Kazuma Fukui, Satoru Takada

  Mar. 2023, Journal of Building Physics, 46(5) (5)

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Deformation of fired clay material during rapid freezing due to supercooling

  Kazuma Fukui, Chiemi Iba, Daisuke Ogura

  Feb. 2023, Journal of Building Physics

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Investigation into the hygrothermal behavior of fired clay materials during the freezing of supercooled water using experiments and numerical simulations

  Kazuma Fukui, Chiemi Iba, Madoka Taniguchi, Kouichi Takahashi, Daisuke Ogura

  In this study, supercooling effects on the hygrothermal behavior of fired clay materials under various experimental conditions, such as water content, cooling rates, and size of specimens were investigated using experimental methods and hygrothermal simulations. We report results of the differential scanning calorimetry (DSC) and temperature distribution changes during a freeze-thaw (FT) experiment using unsaturated specimens. Also, we developed a numerical model of the freezing and thawing processes including the supercooling processes. The DSC results show the freezing of the supercooled water in a fired clay material is considerably faster than that in cement-based materials. It was also found that the dependency of the supercooling effects on the cooling rates seemed to be small. When the water saturation of a material decreases, the rate of the ice saturation increase during the freezing of the supercooled water is decreased while the freezing points of the supercooled water was not changed considerably. The comparison of the results of the FT experiment and hygrothermal simulations show that the combination of the existed hygrothermal model and a modified kinetic equation can reproduce the rapid temperature rise during the freezing of the supercooling water in the FT experiment. Finally, the size effects of specimens on the supercooling phenomenon was discussed based on the experimental and calculation results. The freezing points got higher when a specimen was larger. Due to differences in the ratio of the surface area to the volume, hygrothermal behavior in small specimens and relatively large specimens like that of the DSC and the FT experiment, respectively were markedly different. Water in a relatively large specimen with a small ratio of surface area to volume can achieve the thermodynamic equilibrium in a short period after the freezing starts.

  {SAGE} Publications, May 2022, Journal of Building Physics, 45(6) (6), 723 - 756, English

  [Refereed]

  Scientific journal


• Investigation on the Deterioration Mechanism of Tuff Stones Used for the Exteriors at the Former Koshien Hotel

  Koki Yamada, Chiemi Iba, Tomoko Uno, Kazuma Fukui, Daisuke Ogura

  The former Koshien Hotel is an historic Japanese architectural structure, where two different tuffs called Nikkaseki and Tatsuyamaishi were used to build the exterior. Despite its cultural significance, the building's exterior is deteriorating in many ways, with water permeation being the main factor. In this study, the hygrothermal properties of both Nikkaseki and Tatsuyamaishi were measured in order to examine the correlation between deterioration mechanisms and the tuff characteristics in detail. The basic physical properties, pore size distribution, vapor permeability, hydraulic conductivity, and sorption isotherm were measured. The results of a comparison of two tuffs led us to hypothesize that the main reason behind Nikkaseki's deterioration is expansive freezing, while that of Tatsuyamaishi is caused by repeating dehydration or dry-wet cycles.

  Jun. 2020, E3S Web of Conferences, 172

  [Refereed]

  International conference proceedings


• Experimental investigation and hygrothermal modelling of freeze-thaw process of saturated fired clay materials including supercooling phenomenon

  Kazuma Fukui, Chiemi Iba, Madoka Taniguchi, Kouichi Takahashi, Daisuke Ogura

  To investigate the supercooling phenomenon in fired clay materials, low-temperature differential scanning calorimetry (DSC) and a one-dimensional freeze-thaw (FT) experiment were performed on saturated specimens. The rate of increase in ice saturation during freezing was calculated from the DSC result. Rapid ice growth over a relatively narrow temperature range (within about 0.2 K) was observed at a cooling rate of 0.25 K/min. In the FT experiment, the temperature distribution of a specimen was measured with inserted thermocouples. According to the results of the FT experiment, a rapid temperature increase was observed at sub-zero temperatures accompanied by freezing of the supercooled water. When the supercooled water began to freeze, the released latent heat was found to strongly prevent the specimen temperature from dropping even during the cooling period. Finally, a hygrothermal model of freezing and thawing including a non-equilibrium supercooling process was developed. The freezing rate of the supercooled water was modelled based on the DSC result. The validity of the model was verified by comparing the results of the FT experiment and calculations. The model was found to be able to replicate the rapid temperature rise during the cooling period of the FT experiment.

  Jun. 2020, E3S Web of Conferences, 172

  [Refereed]

  International conference proceedings


• Investigation of thermal, moisture, and mechanical properties of wet and dry fired clay materials to assess frost damage risk

  Kazuma Fukui, Chiemi Iba, Madoka Taniguchi, Kouichi Takahashi, Daisuke Ogura

  Frost action is one of the main causes for deterioration of porous building materials under defined hygrothermal conditions. For an accurate assessment of the frost damage risk under various environmental conditions, thermal, moisture, and mechanical properties should be considered; the hygrothermal properties affect the distribution of temperature and amount of frozen water in the material, whereas the mechanical properties are necessary to predict deformation and damage. Moreover, the dependency of these properties on the moisture content should be understood. Therefore, in this study, thermal, moisture, and mechanical properties of wet and dry fired clay materials were measured. The fired clay materials were sintered at two different temperatures, 1000 °C and 1100 °C (samples T10 and T11, respectively) for comparison. The measured thermal and mechanical properties are considerably different in the wet state compared to the dry state. Freeze–thaw tests were conducted to investigate the relation between the material properties and the frost resistance under a simple experimental condition. As expected, based on the pore structure and obtained mechanical properties, T10 exhibited lower frost resistance than T11 in the freeze–thaw test. Finally, frost damage risk was assessed under various environmental conditions based on the obtained hygrothermal and mechanical properties.

  EDP Sciences, Sep. 2019, MATEC Web of Conferences, 282, 02083 - 02083

  [Refereed]

  Scientific journal


• Effect of air pressure on moisture transfer inside porous building materials

  Kazuma Fukui, Chiemi Iba, Shuichi Hokoi, Daisuke Ogura

  The effect of air pressure on moisture transfer inside porous building materials cannot be omitted in cases where air cannot escape through the surface of the materials; in such cases, air is compressed by the movement of moisture. In this study, we conducted water-absorption tests on a brick specimen. By comparing the result of the experiment on a specimen whose side surfaces were sealed with that of a specimen whose bottom surface was additionally sealed, it was demonstrated that the water-absorption was evidently delayed in the latter case, wherein air could not escape from the specimen except for the top surface, through which water was absorbed. We also developed a numerical model based on the equations for simultaneous air and moisture transfer. The calculated result is reasonably consistent with the experimental result, which supports the validity of the model that includes the change in air pressure in the material and air loss through the top surface as air bubbles. By using this model, the behavior of the air and water inside the specimen was investigated in detail.

  WILEY, Oct. 2018, JAPAN ARCHITECTURAL REVIEW, 1(4) (4), 538 - 547, English

  [Refereed]

  Scientific journal


• EFFECT OF AIR PRESSURE ON MOISTURE TRANSFER INSIDE POROUS BUILDING MATERIALS

  FUKUI Kazuma, IBA Chiemi, HOKOI Shuichi, OGURA Daisuke

   The effect of air pressure on moisture transfer inside porous building materials cannot be ignored in cases where air cannot escape through the surfaces of the materials; in such cases, air is compressed by the movement of the moisture. Such a situation can be brought about by the sealing or surface-protecting materials that prevent water from penetrating into a surface, which is often seen in a typical water absorption test. However, in the field of architectural engineering, the effect of air pressure under wetting processes has not been sufficiently examined, and the validity of calculation models for the transfer of both air and moisture inside materials has not yet been verified. Therefore, this study investigates the behavior of water under the influence of air-pressure changes and develops a proper calculation model for it.
   First, we conducted two types of water absorption tests on bricks. In both of the tests, water infiltrated the specimens through their top surfaces, and the time profiles of the water content were measured using a gamma-ray attenuation method. While only the side surfaces of the specimen were impermeable to moisture and air in Case 1, the side and bottom surfaces were impermeable in Case 2. In Case 2, we expected the air pressure inside the specimen to increase, as the air inside it would not be able to escape through the bottom; this would result in the infiltration of the water being prevented. The results for Case 2 show that the moisture resistance of the specimen was seemingly greater than those obtained in Case 1. We also discovered that the amount of water that was absorbed during Case 2 was not significantly different from the amount absorbed during Case 1. Because air bubbles were observed to have escaped through the water on the top surface in Case 2, we determined that the air pressure inside the specimen returned to atmospheric pressure over time. Therefore, we expected the steady states of Cases 1 and 2 to be similar. It should be noted that the measured water content in Case 2 varied depending on the horizontal position of the measurements.
   Second, we developed a calculation model corresponding to the experiment that was based on the equation for the transfer of both air and liquid water. The calculation results show that the increase in the water content slowed significantly when the changes in the air pressure inside a material were considered. In addition, the calculated and measured water contents agreed well with one another and allowed us to verify the validity of our model. The analysis also showed that when air escapes from the material, the amount that escapes should be adequately considered by the calculation model. According to the results of both the experiments and the simulation, the infiltration process under the influence of the air pressure was as follows: At an early stage in the infiltration process, because the air pressure inside the material was not much higher than atmospheric pressure, water infiltration was not prevented significantly. However, this caused a rapid compression of the air inside the specimen, which resulted in high air pressure within it. This trend reduced the rate of the increase of the air pressure because further water infiltration was reduced by the high pressure. During the final stage of the infiltration, the air pressure began to decrease to atmospheric pressure and water content reached almost the same values as those in Case 1.

  Architectural Institute of Japan, Jan. 2018, Journal of Environmental Engineering (Transactions of AIJ), (743) (743), 39 - 47, Japanese

  [Refereed]


• Moisture behavior inside building materials treated with silane water repellent

  Kazuma Fukui, Chiemi Iba, Shuichi Hokoi

  The application of penetrating water repellent sometimes accelerates degradation of building materials, especially when there are water sources inside such as ground water. A series of experiments using the gamma-ray attenuation method and numerical analysis corresponding to the experiments were performed to reveal the moisture behavior in building materials treated with silane water repellent and to develop a proper numerical model for the repellent layer. The experimental and calculation results show a large difference in water content between the repellent layer and the substrate, which may cause the abovementioned problems.

  2017, Energy Procedia, 132, 735 - 740

  [Refereed]

  International conference proceedings


• Moisture characteristics of water-repellent consolidants and their applicability to existing buildings

  Chiemi Iba, Kazuma Fukui, Shuichi Hokoi

  Water-repellent agents are considered an effective measure of preventing moisture damage in building materials. However, data on the moisture transfer characteristics of repellent materials are insufficient. This study focused on the transfer of liquid water in a porous building material and quantitatively evaluated the applicability of a water-repellent consolidant as a protection agent via water infiltration experiments and numerical analysis. The experimental results could be reproduced by treating the water-repellent consolidant as having two layers with different water conductivities.

  Jul. 2016, AIP Conference Proceedings, 1752

  [Refereed]

  International conference proceedings

• 水分移動を考慮した建築物の耐久性評価に向けて：凍害を引き起こす低温・高含水率条件における水分の挙動に関する検

  福井一真

  Oct. 2024, 第53回熱シンポジウム


• 多孔質建築材料の平衡含水率測定に関する研究:（その１）複数の測定機関による同一材料の測定

  高田暁, 福井一真, 岩本智, 小早川香, 田坂太一, 馬渕賢作, 山田優花

  Aug. 2024, 日本建築学会大会学術講演梗概集


• 積雪・融雪を考慮した多孔質建築外装材の熱水分性状と耐久性の予測に関する研究: 融雪実験による材料内の温度分布と水分浸透に関する検討

  福井一真

  Lead, Aug. 2024, 日本建築学会大会学術講演梗概集


• 氷点下を含む低温環境下における多孔質建築材料の水分拡散係数についての基礎的研究

  小泉陸, 福井一真, 高田暁

  Aug. 2024, 日本建築学会大会学術講演梗概集


• 多孔質建築材料の平衡含水率測定に関する研究: （その2）試験体乾燥時の環境が平衡含水率の測定結果に与える影響

  正田康輔, 福井一真, 高田暁, 岩本智, 小早川香, 田坂太一, 馬渕賢作, 山田優花

  Aug. 2024, 日本建築学会大会学術講演梗概集


• 湿気伝導率の不均一性や局所非平衡を仮定した熱水分同時移動解析による多孔質建築材料の吸湿・透湿過程の再現

  岩本智, 福井一真, 高田暁

  Aug. 2024, 日本建築学会大会学術講演梗概集


• 毛管飽和に達した多孔質建築材料の吸水性状と内部の含水率分布に関する研究

  福井一真

  Lead, Jun. 2024, 日本建築学会近畿支部研究報告集. 環境系


• ALC の吸水性状に水との反応性と空気の entrapment が与える影響

  小林紗也, 福井一真, 高田暁

  Jun. 2024, 日本建築学会近畿支部研究報告集. 環境系


• 湿気伝導率の不均一性や局所非平衡を仮定した熱水分同時移動解析による多孔質建築材料の吸湿・透湿過程の再現

  岩本智, 福井一真, 高田暁

  Jun. 2024, 日本建築学会近畿支部研究報告集. 環境系


• 多孔質建築材料の平衡含水率測定に関する研究: （その１）複数の測定機関による同一材料の測定

  高田暁, 福井一真, 岩本智, 小早川香, 田坂太一, 馬渕賢作, 山田優花

  Jun. 2024, 日本建築学会近畿支部研究報告集. 環境系


• 多孔質建築材料の平衡含水率測定に関する研究: （その2）試験体乾燥時の環境が平衡含水率の測定結果に与える影響

  正田康輔, 福井一真, 高田暁, 岩本智, 小早川香, 田坂太一, 馬渕賢作, 山田優花

  Jun. 2024, 日本建築学会近畿支部研究報告集. 環境系


• 氷点下を含む低温環境下における多孔質建築材料の水分拡散係数についての基礎的研究

  小泉陸, 福井一真, 高田暁

  Jun. 2024, 日本建築学会近畿支部研究報告集. 環境系


• 多孔質建築材料による水蒸気吸着のメカニズムに関する基礎的研究

  岩本智, 福井一真, 高田暁

  2023, 日本建築学会大会学術講演梗概集


• 凍結融解が高含水率状態の多孔質建築材料内の水分の分布におよぼす影響

  福井一真,高田暁

  Lead, 2023, 日本建築学会大会学術講演梗概集


• 多孔質建築材料による水蒸気吸着のメカニズムに関する基礎的研究

  岩本智, 福井一真, 高田暁

  2023, 日本建築学会近畿支部研究報告集. 環境系


• 凍結融解が高含水率状態の多孔質建築材料内の水分の分布におよぼす影響

  福井一真, 高田暁

  Lead, 2023, 日本建築学会近畿支部研究報告集. 環境系


• 凍結融解過程における組積造壁体内の熱水分移動に及ぼすモルタル層の影響に関する基礎的検討

  山中 克, 福井 一真, 高田 暁

  Jul. 2022, 日本建築学会大会学術講演梗概集・建築デザイン発表梗概集, 2022, 1243 - 44


• 静電容量を利用した建築材料の含水率の経時変化の測定と凍結した材料への適用可能性

  福井 一真, 高田 暁

  Jul. 2022, 日本建築学会大会学術講演梗概集・建築デザイン発表梗概集, 2022, 1245 - 1246


• 静電容量を利用した建築材料の含水率の経時変化の測定と凍結した材料への適用可能性

  福井 一真, 高田 暁

  Jun. 2022, 日本建築学会近畿支部研究報告集. 環境系, 62, 57 - 60


• 凍結融解過程における組積造壁体内の熱水分移動に及ぼすモルタル層の影響に関する基礎的検討

  山中 克, 福井 一真, 高田 暁

  Jun. 2022, 日本建築学会近畿支部研究報告集. 環境系, 62, 61 - 64


• 様々な環境条件における多孔質建築材料内の水分の過冷却解消温度の予測 過冷却解消温度と実験条件の関係についての理論的検討

  福井 一真, 伊庭 千恵美, 谷口 円, 高橋 光一, 小椋 大輔

  Jun. 2021, 日本建築学会近畿支部研究報告集. 環境系, 61, 117 - 120


• Anisotropy of deformation of fired clay materials during freezing and thawing: Consideration of anisotropy of the material properties in coupled hygrothermal and mechanical simulations

  福井一真, 伊庭千恵美, 小椋大輔

  2021, 日本建築学会大会学術講演梗概集・建築デザイン発表梗概集(CD-ROM), 2021


• Study on Preservation of Tuff used as Exteriors in Koshien Hotel: Part 4: Measurement of Water Permeability of Tuff Stone

  倉橋哲, 伊庭千恵美, 山田皓貴, 宇野朋子, 福井一真, 小椋大輔

  2021, 日本建築学会大会学術講演梗概集・建築デザイン発表梗概集(CD-ROM), 2021


• Study on Preservation of Tuff used as Exteriors in Koshien Hotel: Part 5: Investigation of Hygrothermal Behaviors inside Tuff Stone

  山田皓貴, 伊庭千恵美, 宇野朋子, 福井一真, 倉橋哲, 小椋大輔

  2021, 日本建築学会大会学術講演梗概集・建築デザイン発表梗概集(CD-ROM), 2021


• 旧甲子園ホテルの凝灰岩外装材の熱水分物性値の測定と平衡含水率の測定方法に関する検討

  山田 皓貴, 伊庭 千恵美, 宇野 朋子, 福井 一真, 小椋 大輔

  Jun. 2020, 日本建築学会近畿支部研究報告集. 環境系, 60, 305 - 308


• Relationship of Temperature and Moisture Conditions to Deformation due to Frost Action: Study on Frost Damage Mechanism of Porous Materials with Thermodynamic Approach: Part 3

  伊庭千恵美, 福井一真, 谷口円, 高橋光一, 小椋大輔

  2020, 日本建築学会大会学術講演梗概集・建築デザイン発表梗概集(CD-ROM), 2020


• Measurement of Thermal Conductivity and Sorption Isotherm of Tuff Stone: Study on Preservation of Tuff used as Exteriors in Koshien Hotel: Part 3

  山田皓貴, 伊庭千恵美, 宇野朋子, 福井一真, 小椋大輔

  2020, 日本建築学会大会学術講演梗概集・建築デザイン発表梗概集(CD-ROM), 2020


• Hygrothermal modeling including supercooling phenomenon in saturated fired clay materials

  福井一真, 伊庭千恵美, 谷口円, 高橋光一, 小椋大輔

  2020, 日本建築学会大会学術講演梗概集・建築デザイン発表梗概集(CD-ROM), 2020


• Study on Conservation of Tuff Stones used as Exteriors at Koshien Hall-Investigation of deterioration mechanisms by measuring environmental conditions and hygrothermal properties-

  山田皓貴, 伊庭千恵美, 宇野朋子, 福井一真, 小椋大輔

  2020, 日本文化財科学会大会研究発表要旨集, 37th


• 41011 4種類の材料の凍結融解過程のエネルギー変化と変形挙動 熱力学的アプローチによる多孔質材料の凍害機構の検討 その2

  伊庭 千恵美, 福井 一真, 谷口 円, 高橋 光一, 小椋 大輔

  日本建築学会, 20 Jul. 2019, 環境工学II, (2019) (2019), 21 - 22, Japanese


• 41033 外装材に使用される凝灰岩の熱水分物性値 旧甲子園ホテルの外装材保存に関する研究 その2

  山田 皓貴, 伊庭 千恵美, 宇野 朋子, 福井 一真, 小椋 大輔

  日本建築学会, 20 Jul. 2019, 環境工学II, (2019) (2019), 65 - 66, Japanese


• 旧甲子園ホテルの凝灰岩外装材の劣化に環境条件と熱水分物性値が及ぼす影響の検討

  山田 皓貴, 伊庭 千恵美, 宇野 朋子, 福井 一真, 小椋 大輔

  Jun. 2019, 日本建築学会近畿支部研究報告集. 環境系, 59, 209 - 212


• 熱力学的アプローチによる多孔質材料の凍害機構の検討 ４種類の材料の凍結融解過程のエネルギー変化と変形挙動

  福井 一真, 伊庭 千恵美, 谷口 円, 高橋 光一, 小椋 大輔

  Jun. 2019, 日本建築学会近畿支部研究報告集. 環境系, 59, 233 - 236


• 41060 多孔質建築材料内の空気圧が水分移動に与える影響の検討 ピンホールの形状と吸水速度の関係

  福井 一真, 伊庭 千恵美, 鉾井 修一, 小椋 大輔

  日本建築学会, 20 Jul. 2018, 環境工学II, (2018) (2018), 119 - 120, Japanese


• 41063 熱力学的アプローチによる多孔質材料の凍害機構の検討 その1 試料の特性とDSC測定条件の検討

  伊庭 千恵美, 福井 一真, 谷口 円

  日本建築学会, 20 Jul. 2018, 環境工学II, (2018) (2018), 125 - 126, Japanese


• 多孔質建築材料内の空気圧が水分移動に与える影響の検討 ピンホールを設けた試験体の吸水実験と空気・水分同時移動解析

  福井 一真, 伊庭 千恵美, 鉾井 修一, 小椋 大輔

  日本建築学会, 23 Jun. 2018, 日本建築学会近畿支部研究報告集. 環境系, (58) (58), 141 - 144, Japanese


• Effect of Air Pressure on Moisture Transfer inside Porous Building Materials Three-dimensional Behavior of Moisture and Air

  Kazuma Fukui, Chiemi Iba, Shuichi Hokoi, Daisuke Ogura

  Lead, International Association of Building Physics (IABP), 2018, Healthy, Intelligent and Resilient Buildings and Urban Environments

  [Refereed]


• 41073 表面含浸材が多孔質建築材料内の空気圧および水分移動に与える影響の検討 空気圧を考慮した水分移動の解析

  福井 一真, 伊庭 千恵美, 鉾井 修一, 小椋 大輔

  日本建築学会, 20 Jul. 2017, 環境工学II, (2017) (2017), 175 - 176, Japanese


• 表面含浸材が多孔質建築材料内の空気圧および水分移動に与える影響の検討

  福井 一真, 伊庭 千恵美, 鉾井 修一, 小椋 大輔

  日本建築学会, 24 Jun. 2017, 日本建築学会近畿支部研究報告集. 環境系, (57) (57), 17 - 20, Japanese


• 防水・撥水剤が建築材料内の水分移動・蓄積に与える影響（その1） 浸透系撥水剤の液相水分伝導率

  福井 一真, 伊庭 千恵美, 吉岡 瑞穂, 鉾井 修一

  日本建築学会, 24 Aug. 2016, 環境工学II, (2016) (2016), 503 - 504, Japanese


• 防水・撥水剤が建築材料内の水分移動・蓄積に与える影響 （その１）－浸透系撥水剤の液相水分伝導率－

  福井 一真, 伊庭 千恵美, 吉岡 瑞穂, 鉾井 修一

  日本建築学会, 25 Jun. 2016, 日本建築学会近畿支部研究報告集. 環境系, (56) (56), 165 - 168, Japanese


• 屋外文化財への適用を目的とした撥水剤処理された建築材料の曝露試験

  福井一真, 伊庭千恵美, 吉岡瑞穂, 鉾井修一

  2016, 日本文化財科学会大会研究発表要旨集, 33rd

• Multiphysics and Multiscale Building Physics: Proceedings of the 9th International Building Physics Conference (IBPC 2024) Volume 1: Moisture and Materials

  Satoshi Iwamoto, Kazuma Fukui, Satoru Takada

  Contributor, Reproduction of Moisture Absorption and Permeation in Porous Building Materials Using Hygrothermal Analysis Assuming Heterogeneity and Local Non-equilibrium, Springer Singapore, Dec. 2024


• Multiphysics and Multiscale Building Physics: Proceedings of the 9th International Building Physics Conference (IBPC 2024) Volume 1: Moisture and Materials

  Kazuma Fukui, Satoru Takada

  Contributor, Potential Impacts of Sealing Methods on the Reliability of Water-Absorption Tests, Springer Singapore, Dec. 2024

• 水分移動を考慮した建築物の耐久性評価に向けて：凍害を引き起こす低温・高含水率条件における水分の挙動に関する検

  福井一真

  第53回熱シンポジウム, Oct. 2024


• 湿気伝導率の不均一性や局所非平衡を仮定した熱水分同時移動解析による多孔質建築材料の吸湿・透湿過程の再現

  岩本智, 福井一真, 高田暁

  日本建築学会大会学術講演梗概集, Aug. 2024


• 多孔質建築材料の平衡含水率測定に関する研究: （その2）試験体乾燥時の環境が平衡含水率の測定結果に与える影響

  正田康輔, 福井一真, 高田暁, 岩本智, 小早川香, 田坂太一, 馬渕賢作, 山田優花

  日本建築学会大会学術講演梗概集, Aug. 2024


• 氷点下を含む低温環境下における多孔質建築材料の水分拡散係数についての基礎的研究

  小泉陸, 福井一真, 高田暁

  日本建築学会大会学術講演梗概集, Aug. 2024


• 積雪・融雪を考慮した多孔質建築外装材の熱水分性状と耐久性の予測に関する研究: 融雪実験による材料内の温度分布と水分浸透に関する検討

  福井一真

  日本建築学会大会学術講演梗概集, Aug. 2024


• 多孔質建築材料の平衡含水率測定に関する研究:（その１）複数の測定機関による同一材料の測定

  高田暁, 福井一真, 岩本智, 小早川香, 田坂太一, 馬渕賢作, 山田優花

  日本建築学会大会学術講演梗概集, Aug. 2024


• 氷点下を含む低温環境下における多孔質建築材料の水分拡散係数についての基礎的研究

  小泉陸, 福井一真, 高田暁

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2024


• 多孔質建築材料の平衡含水率測定に関する研究: （その2）試験体乾燥時の環境が平衡含水率の測定結果に与える影響

  正田康輔, 福井一真, 高田暁, 岩本智, 小早川香, 田坂太一, 馬渕賢作, 山田優花

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2024


• 多孔質建築材料の平衡含水率測定に関する研究: （その１）複数の測定機関による同一材料の測定

  高田暁, 福井一真, 岩本智, 小早川香, 田坂太一, 馬渕賢作, 山田優花

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2024


• 湿気伝導率の不均一性や局所非平衡を仮定した熱水分同時移動解析による多孔質建築材料の吸湿・透湿過程の再現

  岩本智, 福井一真, 高田暁

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2024


• ALC の吸水性状に水との反応性と空気の entrapment が与える影響

  小林紗也, 福井一真, 高田暁

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2024


• 毛管飽和に達した多孔質建築材料の吸水性状と内部の含水率分布に関する研究

  福井一真

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2024


• Water uptake of porous building materials with extremely small air entrapment effects

  Kazuma Fukui, Satoru Takada

  Journal of Physics: Conference Series, Dec. 2023, Abstract When a porous material is near capillary saturation, entrapped air is expected to affect water transfer through the pores. Based on the results of water absorption tests at reduced air pressure, Janssen et al. (Energy Procedia, 2015) demonstrated that air entrapment prevents water absorption above capillary saturation. In this study, to understand the air entrapment effects on water transfer in the high-water-saturation region, we further examined the water transfer characteristics corresponding to extremely small air entrapment effects. First, using three common porous building materials, water uptake experiments were conducted at low air pressure near vacuum (several kilopascals), and the time evolution of the water absorption was measured. The results show that low air pressure accelerates water uptake by brick and aerated concrete specimens, whereas the water uptake by calcium silicate board specimens is not significantly affected. These differences among the materials are discussed from the viewpoint of the pore structure. Furthermore, the results of simultaneous water and air transfer calculations confirm that air entrapment and pressure development in the pores can significantly reduce the rate of water uptake and the water content that a material can reach after capillary absorption.


• 凍結融解が高含水率状態の多孔質建築材料内の水分の分布におよぼす影響

  福井一真, 高田暁

  日本建築学会近畿支部研究報告集. 環境系, 2023


• 多孔質建築材料による水蒸気吸着のメカニズムに関する基礎的研究

  岩本智, 福井一真, 高田暁

  日本建築学会近畿支部研究報告集. 環境系, 2023


• 凍結融解が高含水率状態の多孔質建築材料内の水分の分布におよぼす影響

  福井一真,高田暁

  日本建築学会大会学術講演梗概集, 2023


• 多孔質建築材料による水蒸気吸着のメカニズムに関する基礎的研究

  岩本智, 福井一真, 高田暁

  日本建築学会大会学術講演梗概集, 2023


• 静電容量を利用した建築材料の含水率の経時変化の測定と凍結した材料への適用可能性

  福井 一真, 高田 暁

  日本建築学会大会学術講演梗概集・建築デザイン発表梗概集, Jul. 2022


• 凍結融解過程における組積造壁体内の熱水分移動に及ぼすモルタル層の影響に関する基礎的検討

  山中 克, 福井 一真, 高田 暁

  日本建築学会大会学術講演梗概集・建築デザイン発表梗概集, Jul. 2022


• 凍結融解過程における組積造壁体内の熱水分移動に及ぼすモルタル層の影響に関する基礎的検討

  山中 克, 福井 一真, 高田 暁

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2022


• 静電容量を利用した建築材料の含水率の経時変化の測定と凍結した材料への適用可能性

  福井 一真, 高田 暁

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2022


• Effects of anisotropy of properties of fired clay materials on strain evolution and results of coupled hygrothermal and mechanical simulations during freezing and thawing

  Kazuma Fukui, Chiemi Iba, Daisuke Ogura

  8th International Building Physics Conference, 2021, English

  Oral presentation


• 様々な環境条件における多孔質建築材料内の水分の過冷却解消温度の予測 過冷却解消温度と実験条件の関係についての理論的検討

  福井 一真, 伊庭 千恵美, 谷口 円, 高橋 光一, 小椋 大輔

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2021


• Study on Preservation of Tuff used as Exteriors in Koshien Hotel: Part 5: Investigation of Hygrothermal Behaviors inside Tuff Stone

  山田皓貴, 伊庭千恵美, 宇野朋子, 福井一真, 倉橋哲, 小椋大輔

  日本建築学会大会学術講演梗概集・建築デザイン発表梗概集(CD-ROM), 2021


• Study on Preservation of Tuff used as Exteriors in Koshien Hotel: Part 4: Measurement of Water Permeability of Tuff Stone

  倉橋哲, 伊庭千恵美, 山田皓貴, 宇野朋子, 福井一真, 小椋大輔

  日本建築学会大会学術講演梗概集・建築デザイン発表梗概集(CD-ROM), 2021


• Anisotropy of deformation of fired clay materials during freezing and thawing: Consideration of anisotropy of the material properties in coupled hygrothermal and mechanical simulations

  福井一真, 伊庭千恵美, 小椋大輔

  日本建築学会大会学術講演梗概集・建築デザイン発表梗概集(CD-ROM), 2021


• 旧甲子園ホテルの凝灰岩外装材の熱水分物性値の測定と平衡含水率の測定方法に関する検討

  山田 皓貴, 伊庭 千恵美, 宇野 朋子, 福井 一真, 小椋 大輔

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2020


• Study on Conservation of Tuff Stones used as Exteriors at Koshien Hall-Investigation of deterioration mechanisms by measuring environmental conditions and hygrothermal properties-

  山田皓貴, 伊庭千恵美, 宇野朋子, 福井一真, 小椋大輔

  日本文化財科学会大会研究発表要旨集, 2020


• Hygrothermal modeling including supercooling phenomenon in saturated fired clay materials

  福井一真, 伊庭千恵美, 谷口円, 高橋光一, 小椋大輔

  日本建築学会大会学術講演梗概集・建築デザイン発表梗概集(CD-ROM), 2020


• Measurement of Thermal Conductivity and Sorption Isotherm of Tuff Stone: Study on Preservation of Tuff used as Exteriors in Koshien Hotel: Part 3

  山田皓貴, 伊庭千恵美, 宇野朋子, 福井一真, 小椋大輔

  日本建築学会大会学術講演梗概集・建築デザイン発表梗概集(CD-ROM), 2020


• Relationship of Temperature and Moisture Conditions to Deformation due to Frost Action: Study on Frost Damage Mechanism of Porous Materials with Thermodynamic Approach: Part 3

  伊庭千恵美, 福井一真, 谷口円, 高橋光一, 小椋大輔

  日本建築学会大会学術講演梗概集・建築デザイン発表梗概集(CD-ROM), 2020


• Investigation on the Deterioration Mechanism of Tuff Stones Used for the Exteriors at the Former Koshien Hotel

  Koki Yamada, Chiemi Iba, Tomoko Uno, Kazuma Fukui, Daisuke Ogura

  12TH NORDIC SYMPOSIUM ON BUILDING PHYSICS (NSB 2020), 2020, English, E D P SCIENCES, The former Koshien Hotel is an historic Japanese architectural structure, where two different tuffs called Nikkaseki and Tatsuyamaishi were used to build the exterior. Despite its cultural significance, the building's exterior is deteriorating in many ways, with water permeation being the main factor. In this study, the hygrothermal properties of both Nikkaseki and Tatsuyamaishi were measured in order to examine the correlation between deterioration mechanisms and the tuff characteristics in detail. The basic physical properties, pore size distribution, vapor permeability, hydraulic conductivity, and sorption isotherm were measured. The results of a comparison of two tuffs led us to hypothesize that the main reason behind Nikkaseki's deterioration is expansive freezing, while that of Tatsuyamaishi is caused by repeating dehydration or dry-wet cycles.


• Experimental investigation and hygrothermal modelling of freeze-thaw process of saturated fired clay materials including supercooling phenomenon

  Kazuma Fukui, Chiemi Iba, Madoka Taniguchi, Kouichi Takahashi, Daisuke Ogura

  12TH NORDIC SYMPOSIUM ON BUILDING PHYSICS (NSB 2020), 2020, English, E D P SCIENCES, To investigate the supercooling phenomenon in fired clay materials, low-temperature differential scanning calorimetry (DSC) and a one-dimensional freeze-thaw (FT) experiment were performed on saturated specimens. The rate of increase in ice saturation during freezing was calculated from the DSC result. Rapid ice growth over a relatively narrow temperature range (within about 0.2 K) was observed at a cooling rate of 0.25 K/min In the FT experiment, the temperature distribution of a specimen was measured with inserted thermocouples. According to the results of the FT experiment, a rapid temperature increase was observed at sub-zero temperatures accompanied by freezing of the supercooled water. When the supercooled water began to freeze, the released latent heat was found to strongly prevent the specimen temperature from dropping even during the cooling period. Finally, a hygrothermal model of freezing and thawing including a non-equilibrium supercooling process was developed. The freezing rate of the supercooled water was modelled based on the DSC result. The validity of the model was verified by comparing the results of the FT experiment and calculations. The model was found to be able to replicate the rapid temperature rise during the cooling period of the FT experiment.


• 41033 外装材に使用される凝灰岩の熱水分物性値 旧甲子園ホテルの外装材保存に関する研究 その2

  山田 皓貴, 伊庭 千恵美, 宇野 朋子, 福井 一真, 小椋 大輔

  環境工学II, Jul. 2019, Japanese, 日本建築学会


• 41011 4種類の材料の凍結融解過程のエネルギー変化と変形挙動 熱力学的アプローチによる多孔質材料の凍害機構の検討 その2

  伊庭 千恵美, 福井 一真, 谷口 円, 高橋 光一, 小椋 大輔

  環境工学II, Jul. 2019, Japanese, 日本建築学会


• 熱力学的アプローチによる多孔質材料の凍害機構の検討 ４種類の材料の凍結融解過程のエネルギー変化と変形挙動

  福井 一真, 伊庭 千恵美, 谷口 円, 高橋 光一, 小椋 大輔

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2019


• 旧甲子園ホテルの凝灰岩外装材の劣化に環境条件と熱水分物性値が及ぼす影響の検討

  山田 皓貴, 伊庭 千恵美, 宇野 朋子, 福井 一真, 小椋 大輔

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2019


• Investigation of thermal, moisture, and mechanical properties of wet and dry fired clay materials to assess frost damage risk

  Kazuma Fukui, Chiemi Iba, Madoka Taniguchi, Kouichi Takahashi, Daisuke Ogura

  4TH CENTRAL EUROPEAN SYMPOSIUM ON BUILDING PHYSICS (CESBP 2019), 2019, English, E D P SCIENCES, Frost action is one of the main causes for deterioration of porous building materials under defined hygrothermal conditions. For an accurate assessment of the frost damage risk under various environmental conditions, thermal, moisture, and mechanical properties should be considered; the hygrothermal properties affect the distribution of temperature and amount of frozen water in the material, whereas the mechanical properties are necessary to predict deformation and damage. Moreover, the dependency of these properties on the moisture content should be understood. Therefore, in this study, thermal, moisture, and mechanical properties of wet and dry fired clay materials were measured. The fired clay materials were sintered at two different temperatures, 1000 degrees C and 1100 degrees C (samples T10 and T11, respectively) for comparison. The measured thermal and mechanical properties are considerably different in the wet state compared to the dry state. Freeze-thaw tests were conducted to investigate the relation between the material properties and the frost resistance under a simple experimental condition. As expected, based on the pore structure and obtained mechanical properties, T10 exhibited lower frost resistance than T11 in the freeze-thaw test. Finally, frost damage risk was assessed under various environmental conditions based on the obtained hygrothermal and mechanical properties.


• 41063 熱力学的アプローチによる多孔質材料の凍害機構の検討 その1 試料の特性とDSC測定条件の検討

  伊庭 千恵美, 福井 一真, 谷口 円

  環境工学II, Jul. 2018, Japanese, 日本建築学会


• 41060 多孔質建築材料内の空気圧が水分移動に与える影響の検討 ピンホールの形状と吸水速度の関係

  福井 一真, 伊庭 千恵美, 鉾井 修一, 小椋 大輔

  環境工学II, Jul. 2018, Japanese, 日本建築学会


• 多孔質建築材料内の空気圧が水分移動に与える影響の検討 ピンホールを設けた試験体の吸水実験と空気・水分同時移動解析

  福井 一真, 伊庭 千恵美, 鉾井 修一, 小椋 大輔

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2018, Japanese, 日本建築学会


• Effect of Air Pressure on Moisture Transfer inside Porous Building Materials Three-dimensional Behavior of Moisture and Air

  Kazuma Fukui, Chiemi Iba, Shuichi Hokoi, Daisuke Ogura

  Healthy, Intelligent and Resilient Buildings and Urban Environments, 2018, International Association of Building Physics (IABP)


• 41073 表面含浸材が多孔質建築材料内の空気圧および水分移動に与える影響の検討 空気圧を考慮した水分移動の解析

  福井 一真, 伊庭 千恵美, 鉾井 修一, 小椋 大輔

  環境工学II, Jul. 2017, Japanese, 日本建築学会


• 表面含浸材が多孔質建築材料内の空気圧および水分移動に与える影響の検討

  福井 一真, 伊庭 千恵美, 鉾井 修一, 小椋 大輔

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2017, Japanese, 日本建築学会


• Moisture behavior inside building materials treated with silane water repellent

  Kazuma Fukui, Chiemi Iba, Shuichi Hokoi

  11TH NORDIC SYMPOSIUM ON BUILDING PHYSICS (NSB2017), 2017, English, ELSEVIER SCIENCE BV, The application of penetrating water repellent sometimes accelerates degradation of building materials, especially when there are water sources inside such as ground water. A series of experiments using the gamma-ray attenuation method and numerical analysis corresponding to the experiments were performed to reveal the moisture behavior in building materials treated with silane water repellent and to develop a proper numerical model for the repellent layer. The experimental and calculation results show a large difference in water content between the repellent layer and the substrate, which may cause the abovementioned problems. (c) 2017 The Authors. Published by Elsevier Ltd.


• 防水・撥水剤が建築材料内の水分移動・蓄積に与える影響（その1） 浸透系撥水剤の液相水分伝導率

  福井 一真, 伊庭 千恵美, 吉岡 瑞穂, 鉾井 修一

  環境工学II, Aug. 2016, Japanese, 日本建築学会


• 防水・撥水剤が建築材料内の水分移動・蓄積に与える影響 （その１）－浸透系撥水剤の液相水分伝導率－

  福井 一真, 伊庭 千恵美, 吉岡 瑞穂, 鉾井 修一

  日本建築学会近畿支部研究報告集. 環境系, Jun. 2016, Japanese, 日本建築学会


• 屋外文化財への適用を目的とした撥水剤処理された建築材料の曝露試験

  福井一真, 伊庭千恵美, 吉岡瑞穂, 鉾井修一

  日本文化財科学会大会研究発表要旨集, 2016


• Moisture Characteristics of Water-repellent Consolidants and their Applicability to Existing Buildings

  Chiemi Iba, Kazuma Fukui, Shuichi Hokoi

  THERMOPHYSICS 2016: 21ST INTERNATIONAL MEETING, 2016, English, AMER INST PHYSICS, Water-repellent agents are considered an effective measure of preventing moisture damage in building materials. However, data on the moisture transfer characteristics of repellent materials are insufficient. This study focused on the transfer of liquid water in a porous building material and quantitatively evaluated the applicability of a water-repellent consolidant as a protection agent via water infiltration experiments and numerical analysis. The experimental results could be reproduced by treating the water-repellent consolidant as having two layers with different water conductivities.

• 日本建築学会

  Apr. 2016 - Present

• Pursue of high-efficiency method for measuring moisture property and validation of analytical model focusing on water vapor adsorption process of building materials

  高田 暁, 福井 一真

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Kobe University, 01 Apr. 2023 - 31 Mar. 2027


• Prediction of Deterioration of Tuff Stones Used for Building Exterior Based on Thermal Moisture Stress Analysis

  宇野 朋子, 伊庭 千恵美, 福井 一真

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Mukogawa Women's University, 01 Apr. 2023 - 31 Mar. 2026


• 建築物の凍害リスク評価のための超高含水率領域における熱水分移動現象のモデル化

  福井 一真

  日本学術振興会, 科学研究費助成事業 若手研究, 若手研究, 神戸大学, 01 Apr. 2023 - 31 Mar. 2026


• 木材の長期利用に向けた撥水性・不均一性を考慮した吸水性状の予測モデルの構築

  福井一真

  ノーリツぬくもり財団, 研究助成, 神戸大学, Oct. 2024 - Sep. 2025, Principal investigator


• 熱水分移動と応力・ひずみ変化の連成解析による組積造建築の凍害メカニズムの検討

  福井 一真

  日本学術振興会, 科学研究費助成事業 研究活動スタート支援, 研究活動スタート支援, 神戸大学, 30 Aug. 2021 - 31 Mar. 2023

  2021年度には組積造の壁体を構成するレンガの機械物性の測定を行い、その異方性と不均一性を把握した。さらに、凍結融解過程のレンガのひずみ測定を行い、2022年度に行う予定の凍結融解条件下にある組積造壁体を対象とした熱水分移動・応力・ひずみ変化の連成解析に向け、機械物性とporoelastic parameters、変形の異方性の関係についての理論的検討を行っている。 また、組積造壁体を対象とした一次元の熱水分同時移動モデルを作成し、気象条件の日変動を考慮した壁体内の温度・液相含水率・含氷率の数値計算を行った。これにより、2022年度に行う予定の応力・ひずみ変化を考慮した検討に先立ち、レンガとは著しく物性値が異なるモルタル層が壁体の吸水・凍結過程に及ぼす影響の検討を行った。 モルタルは熱物性はレンガと比較的近いものの、高含水率域における水分伝導率が著しく小さいという特徴がある。壁体の凍結過程ではより低温になりやすい外気側表面の水分の化学ポテンシャルが低下し、壁体内部から水分が流入する。解析結果より、モルタル層が存在することでこのような凍結過程の壁体内の水分移動が妨げられ、壁体の外気側表面での凍結が抑制される一方、壁体のより深い位置まで凍結が進行する可能性があることを示した。 組積造壁体を対象とした検討では数値解析モデルが複雑になることを避けるために均質な物性値を用いて解析を行うことがあるが、本研究において構成材料の物性値の違いの影響を定量的に示したことは意義が大きいと考えている。


• Dynamic mechanism of frost damage on building materials considering supercooling and energy transfer

  伊庭 千恵美, 谷口 円, 高橋 光一

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), Kyoto University, 01 Apr. 2020 - 31 Mar. 2023

  多孔質建築材料内の水分が凍結・融解を繰り返すことで割れや剥離を生じる「凍害」に関し、本研究では過冷却という現象に着目し、凍結・融解過程の材料変形および破壊に至るプロセスを検討する。 2021年度は、新しい示差走査熱流計（DSC）を導入し、まず前年度と同条件・同種の試料を用いて凍結・融解にともなう放熱・吸熱の測定を行い、再現性を確認した。従来の装置は液体窒素を用いて冷却を行っていたが、新しい装置は電子冷却によるため、安定した測定を繰り返し行うことが可能となった。結果として、前年度の実験結果を精度よく再現できた。さらに、DSCを用いて凍結によるより大きな放熱量のデータを得るため、測定時の試料から水分が蒸発することを抑制するためワセリン等を用いた方法を試したが、違いは見られなかった。 DSCで凍結・融解過程を経た試料に、実際にひび割れ等の破壊が生じているかどうかを確認するため、高精度のX線CT装置を用いて３次元画像を得た。凍結融解による明確なひび割れかどうかの判断が困難であったが、試料の作成方法について方針を立てることができた。


• 建築物の凍結融解による劣化の予測モデルの構築と抑制方法の提案

  福井 一真

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for JSPS Fellows, Grant-in-Aid for JSPS Fellows, Kyoto University, Apr. 2019 - Mar. 2021, Principal investigator

  建築材料の凍害は、材料内の水分が凍結と融解を繰り返すことで表面の剥離や亀裂、壁体の剥落などを引き起こす現象である。本研究では、実環境下にある建築部材に適用可能な凍結融解過程の材料の力学挙動の予測モデルを構築することで凍害のリスクを定量化し、その抑制方法を提案することを目的としている。当該年度には、(1)建築材料の凍結による破壊のメカニズムの検討と、(2)過冷却を考慮した建築材料内の熱水分移動の解析モデルの構築を行った。 まず、(1)について、熱分析手法である示差走査熱量測定（DSC）および熱機械分析（TMA）と、凍結融解実験を様々な建築材料を用いて行い、凍結融解過程のエネルギー変化とひずみ変化、凍結融解実験における破壊性状の比較を行った。DSCとTMAでは、すべての材料で内部の水分が過冷却を起こし、凍結時に急激な潜熱の放出と膨張が起こったことから、過冷却水の急速な凍結が材料の損傷に影響を与えている可能性が示唆された。 次に、(2)について、過冷却解消時の凍結は熱力学的平衡状態における凝固点での凍結よりはるかに速いため、熱水分移動モデルの構築のために過冷却解消時の相変化の速度を明らかにする必要があった。そこで、DSCを様々な温度・水分条件下で行い、過冷却解消時の材料内の含氷率の増加速度と温度・水分条件との対応を検討し、凍結速度のモデルを作成した。また、熱電対により凍結融解過程の材料内の温度分布を詳細に測定した。凍結速度モデルを用いて過冷却を考慮した熱水分移動解析モデルを構築し、凍結融解実験に対応する数値解析を行うことで、モデルの妥当性を検証した。その結果から、構築した熱水分移動モデルは過冷却解消過程の材料内の温度上昇を非常によく再現できることを示した。