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：随着时间的推移，混凝土结构在其支撑的重量下变形，如果不更换，最终会导致结构失效。当将混凝土粘结在一起的微观颗粒--被称为硅酸钙-水合物的颗粒--在压力的作用下相互移动时，混凝土就会变形。然而，导致一些混凝土比其他混凝土变形更大的机制还不是很清楚。在这个项目中，研究人员正在研究一系列硅酸钙水合物对压应力的反应。例如，该团队正在研究添加铝的效果，铝现在被添加到一些水泥中，作为一种环境友好的方式来处理金属废物。研究人员正在使用先进的基于X射线的成像技术来直接可视化颗粒对压缩的反应。该项目的结果可以用来提供对混凝土破坏机理的洞察，并提出补救措施，以增加对环境更负责任的基础设施的耐久性。因此，该项目在预测和更换国家-S老化的民用基础设施方面发挥着至关重要的作用。该项目正在培训本科生和研究生；重点是从通常在科学界代表性较低的群体中招募学生加入团队。技术细节：混凝土的一种隐蔽的腐蚀机制是它在压力下的蠕变。蠕变与主要结合相纳米硅酸钙(C-S-H)有关，但人们对这些颗粒如何相互滑动知之甚少。C-S-H颗粒由许多装饰着二氧化硅四面体的氧化钙薄片组成，每一薄片被一层薄的水分子隔开。根据硅的含量或金属的存在，C-S-H的性质可能会有很大的不同。该团队正在使用国内的同步加速器设备测量单轴应力下的颗粒排列(纹理)，以确定颗粒滑移的机制(S)。C-S-H的水环境正在用质子核磁共振弛豫法进行研究，以确定它有多像液体或冰。最后，用单轴应力拉曼光谱研究了硅氧键在应力作用下的应变，以确定在单轴应力作用下结构内部是否存在滑移面。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。该项目的结果对水泥基结构中结构完整性的工程模型很有用。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

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

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.

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

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.

Sequestration of solid carbon in concrete: A large-scale enabler of lower-carbon intensity hydrogen from natural gas

• DOI: 10.1557/s43577-021-00118-z
• 发表时间: 2021-08
• 期刊: MRS Bulletin
• 影响因子: 5
• 作者: Jiaqi Li;L. Spanu;Jeffrey Heo;Wenxin Zhang;David W. Gardner;C. Carraro;R. Maboudian;P. Monteiro