Collaborative Research: In-situ Production of Calcium Carbonate Nanoparticles in Fresh Concrete

合作研究：新拌混凝土中碳酸钙纳米颗粒的原位生产

基本信息

批准号：
1761672
负责人：
Jialai Wang
金额：
$ 31.42万
依托单位：
University of Alabama Tuscaloosa
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-08-15 至 2024-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1761672&HistoricalAwards=false
关键词：
Collaborative Research situ Production Calcium

项目摘要

Portland cement concrete remains the most widely used construction material in the world, and improvements in its properties have the potential for significant benefit in the design and longevity of civil infrastructure. Incorporating nanoparticles to concrete can significantly enhance specific properties, for example strength and durability. However, real applications of nanoparticles in concrete are very limited because of low benefit-cost ratio of using nanoparticles induced by the high manufacturing cost, and difficulty of dispersing nanoparticles. This research studies the in-situ production of nanoparticles in fresh concrete to enhance the engineering performance. A two-step mixing process will be used to produce calcium carbonate nanoparticles in fresh concrete at low cost, as well as to provide well dispersion. Concrete made by this process will have significantly higher strength and better durability due to mechanisms triggered by the nanoparticles. The potential benefit to civil infrastructure, national economy and environmental benefits can be substantial. An aggressive educational plan is designed to complement the research activities, with an emphasis on involving a group of traditionally underrepresented (woman, minority and/or socio-economically disadvantaged) students and high school teachers in the research activities. A series of course modules and special topics lectures will be developed to integrate the research endeavors into classroom teaching at both institutions.In-situ production of calcium carbonate nanoparticles overcomes the major barriers preventing practical applications of nanoparticles in concrete. Three hypotheses have been identified for revealing the working mechanisms of this method: 1) the in-situ produced calcium carbonate nanoparticles promotes cement hydration and tunes the local packing and growth of hydration products, 2) the phase change of nanoparticles from amorphous or metastable to a stable one creates a binding mechanism in concrete, and 3) concrete with calcium carbonate nanoparticles exhibit lower porosity and higher strength due to changing in mineralogy of hydrated cement. A comprehensive experimental and numerical approach will be applied to test these hypotheses. Especially, molecular dynamics simulations will be used to explain the effects of the method on the early hydration of cement; thermodynamic modeling will be employed to quantify the effects on the mineral phase assemblage; advanced material characterization techniques (x-ray diffraction, nuclear magnetic resonance, backscattered electron imaging, etc.) will enable validation of the simulations and quantification of the microstructure. The engineering performance will be determined by the evaluation of mechanical properties and durability testing.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.

波特兰水泥混凝土仍然是世界上使用最广泛的建筑材料，其性能的改进有可能在民用基础设施的设计和寿命中获得巨大利益。将纳米颗粒掺入混凝土可以显着增强特定特性，例如强度和耐用性。但是，由于使用高生产成本引起的使用纳米颗粒的利益成本比较低，因此纳米颗粒在混凝土中的实际应用非常有限，并且很难分散纳米颗粒。这项研究研究了新鲜混凝土中纳米颗粒的原位生产，以提高工程性能。两步混合过程将用于以低成本的新鲜混凝土生产碳酸钙纳米颗粒，并提供井分散。由于纳米颗粒触发的机制，该过程制造的混凝土将具有更高的强度和更高的耐用性。对民用基础设施，国民经济和环境利益的潜在利益可能是可观的。一项积极的教育计划旨在补充研究活动，重点是涉及一群传统上代表性不足的学生（妇女，少数群体和/或社会经济处于弱势群体的学生）和高中教师的研究活动。将开发一系列的课程模块和特殊主题讲座，以将研究努力整合到两个机构的课堂教学中。碳酸钙纳米粒子的静脉生产克服了预防纳米粒子在混凝土中实际应用的主要障碍。已经确定了三个假设以揭示该方法的工作机制：1）原位产生的碳酸钙纳米颗粒促进水泥水合并调节水合产物的局部包装和生长，2）纳米颗粒的相变相变为稳定的纳米颗粒从稳定的碳中呈现的，并在稳定的机构中产生碳纤维机械，并在Concrete concrete concrete and Crcrete concrete，3），以及3）Concrcrete and Crocrete，3）孔隙率和由于水合水泥矿物学的变化而引起的更高强度。将采用全面的实验和数值方法来检验这些假设。特别是，将使用分子动力学模拟来解释该方法对水泥早期水合的影响。将采用热力学建模来量化对矿物相组合的影响；先进的材料表征技术（X射线衍射，核磁共振，反向散射电子成像等）将验证微观结构的仿真和定量。该奖项将通过评估机械性能和耐用性测试来确定工程性能。该奖项反映了NSF的法定任务，并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。