Development of Accelerated Test Methods for Ettringite Related Damage

钙矾石相关损伤加速试验方法的开发

• 批准号: 9988725
• 负责人: Amde Amde
• 金额: $ 5万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-03-15 至 2003-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9988725&HistoricalAwards=false
• 关键词: Development; Accelerated; Test; Methods; Ettringite

Development Of Accelerated Test Methods for Ettringite Related DamageNSF Proposal No. 9988725 (UM No. 990928-8477)ABSTRACT The study will evaluate expansion rate measurement as a possible rapid test method for delayed ettringite formation (DEF). Concrete specimens with different amount of potassium will be cast and stored under high moisture conditions to accelerate DEF. The measured expansion rate data will be analyzed using nonlinear curve fitting algorithms based on the Incomplete Gamma function in order to extract characteristic expansion parameters. These parameters will then be correlated with time-resolved measurements of the amount of ettringite formed, which will be determined through a combination of scanning electron microscopy, quantitative X-ray diffraction, synchrotron radiation energy dispersive diffraction, and other means. In addition, computer tomography will be used for 3D imaging of crack propagation. Weight gain as a function of humidity cycling will also be explored as a possible alternative rapid test method. The formation of ettringite or ASR gel involves the uptake of water, which results in a permanent weight, or mass, gain of the sample. Since mass can be measured more sensitively and conveniently than length change, this suggests the possibility of replacing the expansion measurement with a weight change measurement that is more directly related to DEF. The study will contribute to the understanding of the cause for the distress mechanism in DEF, and will contribute to the development of a rapid test method for DEF.

钙矾石相关损伤加速试验方法的开发NSF提案编号9988725（UM编号990928-8477）摘要 该研究将评估膨胀率测量作为延迟钙矾石形成（DEF）的可能快速测试方法。将不同掺钾量的混凝土试件浇注并在高湿度条件下储存以加速DEF，采用基于不完全Gamma函数的非线性曲线拟合算法对膨胀率实测数据进行分析，提取特征膨胀参数。 然后将这些参数与所形成的钙矾石的量的时间分辨测量值相关联，所形成的钙矾石的量将通过以下组合来确定： 扫描电子显微镜、定量X射线衍射、同步辐射能量色散衍射等手段。此外，计算机断层扫描将用于裂纹扩展的3D成像。 还将探索作为湿度循环函数的增重，作为可能的替代快速试验方法。 钙矾石或ASR凝胶的形成涉及水的吸收，这导致样品的永久重量或质量增加。 由于质量可以比长度变化更灵敏和更方便地测量，这表明可以用与DEF更直接相关的重量变化测量代替膨胀测量。 本研究将有助于了解DEF的痛苦机制的原因，并将有助于DEF的快速测试方法的发展。