Fundamental Investigation of Preferred Orientation Mechanism in Concrete

混凝土择优取向机制的基础研究

• 批准号: 1935604
• 负责人: Roya Maboudian
• 金额: $ 55.9万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1935604&HistoricalAwards=false
• 关键词: Fundamental; Investigation; Preferred; Orientation; Mechanism

NON-TECHNICAL DESCRIPTION: Over time, concrete structures deform under the weight they support, which ultimately leads to structural failure if not replaced. The concrete deformation is caused when the microscopic grains that bind the concrete together - grains known as calcium-silicate-hydrate - are compelled by the compressive force to move past each other. However, the mechanism that causes some concretes to deform more than others is not well understood. In this project, researchers are studying how a series of calcium-silicate-hydrates responds to compressive stress. For example, the team is examining the effect of adding aluminum, which is now being added to some cements as an environmentally friendly way to dispose of metal wastes. The researchers are using advanced X-ray-based imaging techniques to directly visualize how the grains respond to compression. The results of this project can be used to provide insights into concrete failure mechanisms and suggest remedies to increase durability towards more environmentally responsible infrastructure. As such, this project plays a crucial role in the forecasting and replacement of the nation?s aging civil infrastructure. The project is training both undergraduate and graduate students; an emphasis is placed on recruiting students from groups typically underrepresented in the sciences to join the team.TECHNICAL DETAILS: An insidious decay mechanism of concrete is its creep under stress. The main binding phase, nanocrystalline calcium-silicate-hydrate (C-S-H), is implicated in the creep, but there is very little understanding of how these grains slide past each other. C-S-H grains comprise a number of calcium oxide sheets decorated with silica tetrahedra, where each sheet is separated by a thin layer of water molecules. Depending on the amount of silicon or if metals are present, the properties of the C-S-H can vary significantly. The team is using domestic synchrotron facilities to measure grain alignment (texturing) under uniaxial stress towards determining the mechanism(s) of grain slippage. The water environment in C-S-H is being studied with proton nuclear magnetic resonance relaxometry to determine how liquid- or ice-like it is. Finally, the strain in silicon - oxygen bonds under stress is being studied with uniaxial-stress Raman spectroscopy to determine if there are slip planes within the structure under uniaxial stress. The development of uniaxial-stress Raman spectroscopy will be useful for understanding similar phenomena in other nanocrystalline ceramic materials. The results of the project are useful for engineering models of structural integrity in cement-based structures.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术描述：随着时间的流逝，混凝土结构在其支持的重量下变形，这最终导致结构故障，如果不替换。当将混凝土结合在一起的微观晶粒（称为钙 - 硅酸盐水合物）被压缩力互相移动时，引起混凝土变形。但是，导致某些混凝土变形的机制比其他混凝土变形更多。在该项目中，研究人员正在研究一系列钙硅酸盐水合物如何应对压力。例如，该团队正在研究添加铝的效果，该铝现在正在将其添加到某些水泥中，作为一种环保的方式来处理金属废物。研究人员正在使用高级基于X射线的成像技术直接可视化谷物对压缩的反应。该项目的结果可用于提供对具体失败机制的见解，并建议补救措施，以提高对更环保的基础设施的耐用性。因此，该项目在国家衰老的民用基础设施的预测和替代中起着至关重要的作用。该项目正在培训本科生和研究生。重点是从科学中招募通常不足的团队的学生加入团队。技术细节：混凝土的阴险衰减机制是其压力下的蠕变。主要的结合阶段，纳米晶钙 - 硅酸盐水合物（C-S-H）涉及到蠕变，但对这些谷物如何相互滑动几乎没有理解。 C-S-H晶粒包含许多用二氧化硅四面体装饰的氧化钙片，每张纸都被薄薄的水分子隔开。根据硅的数量或存在金属的不同，C-S-H的性质可能会有很大变化。该团队正在使用家庭同步设备在单轴压力下测量谷物对齐（纹理），以确定谷物滑移的机制。用质子核磁共振弛豫计对C-S-H中的水环境进行了研究，以确定其液态或冰样的样子。最后，用单轴压力拉曼光谱法研究了应力下的硅 - 氧键，以确定在单轴应力下结构内是否存在滑移平面。单轴应力拉曼光谱的发展将有助于理解其他纳米晶陶瓷材料中的类似现象。该项目的结果对于基于水泥的结构中结构完整性的工程模型很有用。该奖项反映了NSF的法定任务，并且使用基金会的知识分子优点和更广泛的影响评估标准，被认为值得通过评估来获得支持。

项目成果

Influences of cross-linking and Al incorporation on the intrinsic mechanical properties of tobermorite

• DOI: 10.1016/j.cemconres.2020.106170
• 发表时间: 2020-10-01
• 期刊: CEMENT AND CONCRETE RESEARCH
• 影响因子: 11.4
• 作者: Li, Jiaqi;Zhang, Wenxin;Monteiro, Paulo J. M.
• 通讯作者: Monteiro, Paulo J. M.

Synchrotron X-ray Raman scattering shows the changes of the Ca environment in C-S-H exposed to high pressure

• DOI: 10.1016/j.cemconres.2020.106066
• 发表时间: 2020-06
• 期刊: Cement and Concrete Research
• 影响因子: 11.4
• 作者: Jiaqi Li;Wenxin Zhang;P. Monteiro

Structure and Intrinsic Mechanical Properties of Nanocrystalline Calcium Silicate Hydrate

• DOI: 10.1021/acssuschemeng.0c03230
• 发表时间: 2020-08-24
• 期刊: ACS SUSTAINABLE CHEMISTRY & ENGINEERING
• 影响因子: 8.4
• 作者: Li, Jiaqi;Zhang, Wenxin;Monteiro, Paulo J. M.
• 通讯作者: Monteiro, Paulo J. M.

The nanomechanical properties of non-crosslinked calcium aluminosilicate hydrate: The influences of tetrahedral Al and curing age

非交联硅铝酸钙水合物的纳米力学性能：四面体Al和养护龄期的影响

• DOI: 10.1016/j.cemconres.2022.106900
• 发表时间: 2022
• 期刊: Cement and Concrete Research
• 影响因子: 11.4
• 作者: Li, Jiaqi;Zhang, Wenxin;Sanz-Camacho, Paula;Duttine, Mathieu;Gardner, David;Carraro, Carlo;Maboudian, Roya;Huthwelker, Thomas
• 通讯作者: Huthwelker, Thomas

In-situ microtomography image segmentation for characterizing strain-hardening cementitious composites under tension using machine learning

• DOI: 10.1016/j.cemconres.2023.107164
• 发表时间: 2023-07
• 期刊: Cement and Concrete Research
• 影响因子: 11.4
• 作者: Ke-shu Xu;Q. Jin;Jiaqi Li;D. Ushizima;V. Li;K. Kurtis;P. Monteiro