Development of a technology to control thermal cracking in concrete by means of a smart material

开发利用智能材料控制混凝土热裂的技术

• 批准号: 15206061
• 负责人: MIHASHI Hirozo
• 金额: $ 27.79万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15206061/
• 关键词: microcapsule; hydration-rate; thermal cracking; smart material; retardation effect; 水和反応; 遅延剤; 水和熱

Hydration heat of cement in massive concrete causes significant thermal stress leading to cracking at early ages. In order to avoid such a stress, a smart material for controlling the hydration heat is developed in this study. As the first step, the influence of curing temperature history on mechanical properties of concrete is quantitatively discussed as a function of equivalent age. It was confirmed that high temperature curing of concrete at the early ages prevents the increase of strength in the matured condition. On the basis of these results, the melting temperature of paraffin microcapsule was chosen to be less than 60 degree C. Smart materials developed in this study are composed of paraffin microcapsule containing very fine particles of a hydration-retarder agent. Hence the rising rate of temperature of concrete and thermal stress are controlled under the specified value. Performance and applicability for practical purpose of the developed smart materials are verified by a ser … More ies of experimental studies. Conclusively the following results are obtained :1. Timing and technique of mixing the microcapsules with fresh concrete was one of the most difficult subjects in this study. While microcapsule are easily damaged during concrete mixing, adding the microcapsules to fresh concrete in agitator at the construction site just before placing the concrete is most acceptable for the practical purpose.2. Amount of microcapsules necessary for controlling the hydration rate of concrete is strongly dependent on the type of used fine aggregates. Therefore it is essential to examine the necessary amount of the microcapsules in advance.3. Reduction of hydration heating rate does reduce the thermal stress in concrete, though the maximum temperature is the same as that of plain concrete in case of a very thick and massive concrete. For the practical application, the necessary amount of microcapsule needs to be determined by analyzing the thermal diffusion process in the thickness of the member given in the design documents since the maximum temperature is much lower than that of the adiabatic condition as obtained in the experimental study especially when the hydration heating rate is reduced. Less

大体积混凝土中水泥的水化热会产生较大的温度应力，导致混凝土早期开裂。为了避免这种应力，智能材料控制水化热在这项研究中的发展。作为第一步，作为等效龄期的函数，定量地讨论了养护温度历史对混凝土力学性能的影响。试验结果表明，混凝土早期高温养护不利于成熟期强度的提高。在这些结果的基础上，石蜡微胶囊的熔融温度被选择为小于60 ℃。本研究所开发的智能材料由石蜡微胶囊组成，微胶囊中含有非常细的水化阻滞剂颗粒。从而使混凝土的温升速率和温度应力控制在规定值以下。通过一系列的实验验证了所研制的智能材料的性能和实用性 ...更多信息 实验研究的结果。得出以下结论：1.微胶囊与新拌混凝土的混合时间和技术是本研究中最困难的课题之一。而微胶囊在混凝土搅拌过程中易被破坏，在施工现场混凝土浇筑前将微胶囊加入到搅拌机中的新拌混凝土中是最可行的.控制混凝土水化速率所需的微胶囊量强烈依赖于所用细骨料的类型。因此，有必要提前检查微胶囊的必要量。3.降低水化加热速率确实降低了混凝土中的温度应力，但在很厚的大体积混凝土中，最高温度与素混凝土相同。对于实际应用，需要通过分析设计文件中给定的构件厚度中的热扩散过程来确定所需的微胶囊量，因为最高温度远低于实验研究中获得的绝热条件下的最高温度，特别是当水化加热速率降低时。少

项目成果

Prediction Method of Mechanical Properties of Concrete Cured in Different Temperatures and its Applicability

不同温度养护混凝土力学性能预测方法及其适用性

• 发表时间: 2004
• 期刊: Journal of Structural and Construction Engineering (Transactions of AIJ) No.577
• 作者: 小峯 裕己;木村 洋 他;Norio Ito
• 通讯作者: Norio Ito

インテリジェント材料を用いたコンクリートの温度応力制御技術の開発に関する研究,(その2)実機施工実験による施工性の検討

智能材料混凝土温度应力控制技术开发研究（二）通过实机施工实验检验和易性

• 发表时间: 2006
• 期刊: 日本建築学会東北支部研究報告集 69号(構造系)(印刷中)
• 作者: 前原恵二;梅澤めぐみ;木村洋;谷合哲行;小峯裕己;西山 直洋
• 通讯作者: 西山 直洋

Concrete of Thermal stress in Early Age Concrete with Smart Material (Part II) Experimental Study on Application of Smart Concrete to In-situ Execution

智能材料早龄混凝土热应力混凝土（下）智能混凝土现场施工应用试验研究

• 发表时间: 2006
• 期刊: Proceedings of AIJ Tohoku Chapter Architectural Research Meeting No.69(in print)
• 作者: Naohiro Nishiyama

インテリジェント材料を用いたコンクリートの温度応力制御技術の開発に関する研究,(その1)ワックスコーティング型マイクロカプセルの性能と各種影響因子

智能材料混凝土温度应力控制技术发展研究（一）蜡包微胶囊性能及各种影响因素

• 发表时间: 2006
• 期刊: 日本建築学会東北支部研究報告集 69号(構造系)(印刷中)
• 作者: 竹内 徹

Concrete of Thermal stress in Early Age Concrete with Smart Material (Part I) Performance of Microcapsule Made with Wax Coating Technique and Influencing Factors

智能材料早龄期混凝土热应力（上）涂蜡微胶囊性能及影响因素

• 发表时间: 2006
• 期刊: Proceedings of AIJ Tohoku Chapter Architectural Research Meeting No.69(in print)
• 作者: 梅澤めぐみ;前原恵二;木村洋;谷合哲行;小峯裕己;Tohru Takeuchi
• 通讯作者: Tohru Takeuchi