2022 Fiscal Year Final Research Report

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

Research Project

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Project/Area Number	20K04789
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Review Section	Basic Section 23010:Building structures and materials-related
Research Institution	Kyoto University
Principal Investigator	Iba Chiemi 京都大学, 工学研究科, 准教授 (10462342)
Co-Investigator(Kenkyū-buntansha)	谷口円地方独立行政法人北海道立総合研究機構, 建築研究本部北方建築総合研究所, 研究主幹 (20462351) 高橋光一地方独立行政法人北海道立総合研究機構, 建築研究本部北方建築総合研究所, 研究職員 (00826787) 福井一真神戸大学, 工学研究科, 助教 (00908767)
Project Period (FY)	2020-04-01 – 2023-03-31
Keywords	凍結融解 / 過冷却 / 凍害 / DSC / TMA / エネルギー / ひずみ / 材料変形
Outline of Final Research Achievements	In this study, we focused on the supercooling phenomenon and investigated the process of material deformation and destruction during the freeze-thaw process using differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and X-ray CT images. We found that some samples exhibited energy changes after the freeze-thaw process by improving the measurement accuracy of DSC, and the residual strain due to freeze-thaw was detected by TMA. However, distinctive fracture in the material was difficult to discriminate from the X-ray CT image, and the correspondence between the degree of damage, energy change and residual strain could not be quantified. On the other hand, by combining the heat and moisture transfer model in the material considering the supercooling process and the deformation model due to the water pressure change in the material based on poromechanics, the temperature and strain change in the freeze-thaw experiment conducted separately could be well reproduced.
Free Research Field	建築環境工学
Academic Significance and Societal Importance of the Research Achievements	本研究では、先行研究で測定精度上の限界により検出できなかった材料の凍結融解によるエネルギー変化を、検出できる程度に測定精度を高めることができた。ひび割れ等の明確な破壊とエネルギーとの対応は定量化できなかったものの、凍害の根本的な原因である水の相変化と、材料力学的な局所破壊をエネルギーという点で結び付けるという本来の目的に関しては、基礎情報の積み上げができたといえる。また、本研究で用いた熱分析手法は、一般的な材料の凍結融解試験と比較し所要時間がはるかに短くて済むため、種々の材料の凍結融解抵抗性の評価を簡便に行うことができると考えらえる。