A Bottom-up Approach to Design of Chemical Soil Stabilization Using Thermodynamic Modeling

使用热力学模型设计化学土壤稳定的自下而上方法

• 批准号: 1740554
• 负责人: Maria Chrysochoou
• 金额: $ 25.67万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-15 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1740554&HistoricalAwards=false
• 关键词: Bottom; up; Approach; Design; Chemical

Clay soils are present in large parts of the United States, such as Texas, Oklahoma, Kansas and others. Since clay soils are unsuitable as foundations for construction of highways and other structures, various stabilization techniques are employed to improve their properties. Chemical soil stabilization using lime and Portland cement is among the most widely applied approaches. Typically, design of soil stabilization requires the performance of lab scale treatability studies in order to determine the optimal chemical dosage, and there is still limited ability to predict the long-term behavior of stabilized soils over months and years. Models that describe the chemical reactions within stabilized clays over time are currently lacking and are necessary to improve our predictive ability. Accordingly, the overarching goal of this project is to generate the fundamental kinetic and thermodynamic models that will quantitatively describe the evolution of the chemical reactions between clay minerals and common stabilizers (lime, Portland cement). The long-term vision of the project is to utilize the models to predict long term behavior of stabilized clays and inform the mix design, minimizing the need to conduct treatability studies. In addition, the models will be tools for assessing the behavior of chemically stabilized soils under different scenarios (e.g. increased carbonation or impact of acidification).Model development will be done for eight different combinations (pure kaolinite with different particle sizes, pure Na-bentonite and one soil stabilized with quicklime and Portland cement) that will be provide a) fundamental data for pure minerals; and b) insight into the applicability on a real soil. Three different techniques (quantitative X-ray Diffraction, thermogravimetric and differential thermal analysis and Nuclear Magnetic Resonance) will be employed to monitor the solid phase composition in pure and reactive systems over time, utilizing advanced spectra deconvolution techniques. The generated data will be used to fit kinetic models for the pozzolanic reactions of each clay mineral. In addition, monitoring of pore solution composition will allow to conduct both forward and inverse thermodynamic modeling to predict the system stability and potential evolution. Due to the multi-disciplinary nature of the project, a parallel goal is to provide training opportunities integrating geotechnical engineering, geochemistry and materials science. Specifically designed modules with project-related multi-disciplinary concepts will be designed and integrated in regularly offered teaching and outreach activities at UCONN, providing a sustainable platform for continuous exposure of wide student audiences and expanding existing initiatives, from K-4 soil modules, to an ASCE webinar for professionals, new undergraduate courses and a distance learning Masters of Engineering. Engagement across three professional societies (chemistry, environmental and civil engineering) will result in cross-fertilization and wide dissemination of project results.

粘土存在于美国的大部分地区，如德克萨斯州、俄克拉荷马州、堪萨斯等。由于粘土不适合作为公路和其他建筑物的基础，因此采用各种稳定技术来改善其性质。使用石灰和波特兰水泥的化学土壤稳定是应用最广泛的方法之一。通常，土壤稳定的设计需要进行实验室规模的可处理性研究，以确定最佳的化学剂量，并且预测稳定土壤在数月和数年内的长期行为的能力仍然有限。目前缺乏描述稳定粘土内随时间变化的化学反应的模型，这对于提高我们的预测能力是必要的。因此，该项目的首要目标是生成基本的动力学和热力学模型，这些模型将定量描述粘土矿物和常见稳定剂（石灰、波特兰水泥）之间的化学反应的演变。该项目的长期愿景是利用模型来预测稳定粘土的长期行为，并为配合比设计提供信息，最大限度地减少进行可处理性研究的需要。此外，这些模型将成为评估化学稳定土壤在不同情况下的行为的工具（例如，碳酸化增加或酸化影响）。将针对八种不同的组合进行模型开发（不同粒度的纯高岭石、纯钠基膨润土和一种用生石灰和波特兰水泥稳定的土壤），将提供a）纯矿物的基本数据;以及B）对真实的土壤上的适用性的洞察。将采用三种不同的技术（定量X射线衍射、热重和差热分析以及核磁共振），利用先进的光谱去卷积技术，监测纯体系和反应体系中随时间推移的固相组成。生成的数据将用于拟合每种粘土矿物的火山灰反应的动力学模型。此外，监测孔隙溶液组成将允许进行正向和反向热力学建模，以预测系统稳定性和潜在的演变。由于该项目的多学科性质，一个平行的目标是提供整合岩土工程，地球化学和材料科学的培训机会。专门设计的模块与项目相关的多学科概念将被设计和整合在UCONN定期提供的教学和推广活动，提供了一个可持续的平台，不断接触广泛的学生观众和扩大现有的举措，从K-4土壤模块，ASCE网络研讨会的专业人士，新的本科课程和远程学习工程硕士。三个专业学会（化学、环境和土木工程）的参与将促进项目成果的相互促进和广泛传播。

项目成果

Strength Development and Reaction Kinetics in Lime-Treated Clays

石灰处理粘土的强度发展和反应动力学

• DOI: 10.1061/9780784484012.014
• 发表时间: 2022
• 期刊: Geo-Congress 2022
• 作者: Ahmadullah, Tasneem;Chrysochoou, Maria
• 通讯作者: Chrysochoou, Maria