A Thermo-Kinetic Approach to Enhance the Use of Clays in Concrete

为了应对基础设施建设对可持续混凝土不断增长的需求，过去的研究已经确定了碳高效材料（如粉煤灰、矿渣）来部分替代混凝土中的水泥。然而，只有当这些材料在混凝土环境中表现出增强的反应性时，大量使用这些材料才有益。由于这些材料的基本组成-反应性关系尚未很好地建立，它们的选择是基于基于试错的方法，这是不可靠的，并且经常导致性能下降。这些材料质量低，供应有限，进一步使它们不能作为建筑材料采用。因此，为了产生重大的全球影响，需要确定并适应混凝土中使用的丰富、廉价、低碳和高活性的材料。粘土在所有地质环境中都很丰富，符合所有这些标准。这项研究的目的是通过用粘土和其他现成的无机材料代替高达70%的水泥来配制混凝土粘合剂。基于反应性、热力学相互作用和微观结构发展的准确表征，采用整体方法来制定成本和节能策略，以提高粘土的反应性，包括广泛使用的低等级粘土，从而促进其作为混凝土的水泥替代材料的使用。总的来说，这项工作的结果将在不牺牲性能的情况下为混凝土中大量粘土的比例方法定义一个新的范例，从而为广泛采用真正可持续的混凝土指明了道路。知识传播活动，包括培训代表性不足的学生和宣传活动，使专业人员和一般受众了解设计富含粘土的可持续混凝土的经济和社会影响，将扩大本研究的影响。本研究采用协调的实验和计算任务来阐明可持续粘合剂系统的基本组成-反应性-微观结构-性能相关性。先进的结构表征和新型的基于微热量的反应性评估技术串联使用，将粘土的组成与其反应性联系起来。这些知识被用于开发节能活化程序，以最大限度地提高粘土的反应性，包括缺乏高岭石的粘土。热力学模型与实验相结合，用来加强粘合剂？通过控制无机添加剂的添加，无机添加剂与水泥和粘土协同作用，最大限度地形成填充空间的反应产物。采用一系列微观结构和性能表征技术，包括基于微结构的三维晶格玻尔兹曼方法，将微结构演变与工程性能的发展联系起来。这是随后的规范为基础的工程性能的混凝土与粘土丰富的可持续粘合剂的严格评估。从这些研究中获得的知识被整合到制定指导方针中，从而能够选择和调节粘土的物理/化学特性，从而设计出具有增强性能的可持续混凝土。

In response to the incessantly increasing demand for sustainable concretes for the construction of infrastructure, past studies have identified carbon-efficient materials (e.g., fly ash, slag) for partial replacement of cement in concrete. High-volume use of these materials, however, is only beneficial when they exhibit enhanced reactivity in concrete environments. As fundamental composition-reactivity relationships for these materials are not well established, their selection is based on trial-and-error based approaches, which are unreliable and often lead to impoverished performance. Low quality and limited availability of such materials further marginalizes their adoption as construction materials. Therefore, to have a significant global impact, abundant, inexpensive, carbon-efficient, and highly reactive materials need to be identified and adapted for use in concrete. Clays, which are abundant in all geological settings, meet all of these criteria. This research aims to formulate binders for concrete by replacing up to 70% of cement with clays and other readily available inorganic materials. A holistic approach, based on accurate characterizations of reactivity, thermodynamic interactions and microstructural development, is employed to develop cost- and energy-efficient strategies to achieve enhanced reactivity of clays, including widely available low-grade clays, thus promoting their use as cement replacement materials for concrete. Overall, outcomes of this work will define a new paradigm in methods of proportioning high volumes of clay in concretes without conceding performance, thereby charting a path for widespread adoption of truly sustainable concretes. Knowledge dissemination activities, including training of underrepresented students and outreach activities to inform professionals and general audience of the economic and societal impacts of designing clay-rich sustainable concretes, will extend the impact of this research. This study employs harmonized experimental and computational tasks to elucidate fundamental composition-reactivity-microstructure-property correlations in sustainable binder systems. Advanced structure characterization and novel microcalorimetry-based reactivity-assessment techniques are used in tandem to link composition of clays to their reactivity. This knowledge is used to develop energy-efficient activation procedures that maximize the reactivity of clays, including kaolinite-deficient clays. A thermodynamic model in conjunction with experiments is used to bolster the binder?s reactivity through controlled additions of inorganic additives that synergistically interact with cement and clay to maximize the formation of space-filling reaction products. A suite of microstructure and performance characterization techniques, including a microstructure-based 3D lattice Boltzmann method, are employed to relate the microstructural evolution to the development of engineering properties. This is followed by rigorous evaluations of specification-based engineering properties of concrete made with clay-rich sustainable binders. Knowledge gained from these studies are consolidated to develop guidelines that enable selection and regulation of physical/chemical properties of clays to design sustainable concretes with enhanced properties.