Development of the self-compacted and high-strength concrete for cold region

寒地自密实高强混凝土的研制

• 批准号: 12450216
• 负责人: NAWA Toyoharu
• 金额: $ 4.8万
• 依托单位: HOKKAIDO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450216/
• 关键词: Self-compacted and high-strength concrete for cold region; Graft Copolymer; Autogenous shrinkage; Fly ash; Ionic concentration; Mix design of concrete; Monte Carlo method; Fractal theory; 高強度コンクリート; 高性能AE減水剤; 温度; 初期高温養生; 強度発現; 硫酸アルカリ; 粒度分布 /

This purpose of this study is to develop the self-compacting and high-strength concrete for the cold region to reduce an environmental load. Most important results are summarized as follwos :(1) We developed the superplasticizer for the self-compacting and high-strength concrete in cold region. The effect of the chemical structure of superplasticizer on the fluidity, fluidity retention, retardation of hydration, and high durability of concrete was examined when the temperature was varied. As a result, it was confirmed that the heterologous graft copolymer having a long and short graft chains shows highly cement dispersed and low retardation of cement hydration, and the graft copolymer containing longer graft chains satisfied both high fluidity and high durability of concrete at low temperature.(2) It was indicated that the reduction of autogenous shrinkage of concrete is very important to prevent cracking the self-compacting and high-strength concrete for the cold region. Moreover, it was imposed that both to control the ionic concentration of liquid phase in concrete and to containing a large amount of fly ash were able to decrease the autogenous shrinkage.(3) The prediction method of the mix proportion for the self-compacted and high-strength concrete was proposed in order to make concrete mix design easily when the quality of powder and aggregate were varied. The critical state of self-compactability could be asumed that the bridge structure of the coarse aggregate covered with adherent mortar firms and was influenced strongly by the concentration of coarse aggregate and the fluidity of mortar. Based on this assumption, the maximum values of both coarse aggregate and fine aggregate and the unit water content (water-powder ratio) when concrete was satisfied of the self-compactability could be calculated by using the probability model based on the Monte Carlo method and the fractal theory respectively.

本研究的目的是开发适用于寒冷地区的自密实高强混凝土，以减轻环境负荷。主要研究成果如下：(1)开发了寒区自密实高强混凝土高效减水剂。研究了不同温度下高效减水剂的化学结构对混凝土流动性、流动性保持性、水化延迟性和高耐久性的影响。结果表明，具有长、短接枝链的异种接枝共聚物具有较高的水泥分散性和较低的水泥水化延迟性，而具有较长接枝链的接枝共聚物则满足混凝土的高流动性和低温耐久性。(2)表明，减少混凝土的自收缩对于防止自密实混凝土开裂非常重要。 寒冷地区高强混凝土。此外,控制混凝土液相离子浓度和掺入大量粉煤灰均能减少自密实收缩。(3)提出了自密实高强混凝土配合比的预测方法,以便在粉料和骨料质量发生变化时便于进行混凝土配合比设计。自密实性的临界状态可以认为是粗骨料的桥结构被粘附砂浆覆盖而牢固，并且受粗骨料浓度和砂浆流动性的强烈影响。在此假设基础上，分别采用基于蒙特卡罗法和分形理论的概率模型计算出混凝土满足自密实性时粗骨料和细骨料的最大值以及单位含水量（水粉比）。