CAREER: Reaction Mechanisms, Performance Assessment, and Novel Mitigation Tools for Alkali-Silica Reaction in Concrete Structures

该学院早期职业发展(CALEAR)项目将促进对易受碱-硅酸反应(ASR)影响的混凝土结构的劣化机制、损伤缓解和使用寿命性能预测的知识水平。该研究方法分离了三个基本的ASR反应(二氧化硅溶解、凝胶化和溶胀)，并将每个反应的热力学平衡和动力学表征为体系的化学(即物种浓度和相互作用)和物理(如温度、压力、湿度)的函数。这将显著阐明集料矿物学和粘结剂组成的反应机理和作用，并可导致开发适用于新结构和现有结构的更有效的ASR抑制外加剂和外加剂输送方法。此外，还开发了新的测试和建模工具，以快速可靠地评估ASR风险，并定量预测含有潜在活性集料的混凝土的耐久性能。最后，对新出现的碱激发混凝土中的ASR进行了研究，以提高这些绿色材料的可靠性和市场接受度。该项目将多尺度实验与多尺度(地球化学、反应传输和性能预测)建模相结合，以有效地实现这些研究目标。除了推进ASR科学，这些发现可能对加速新的火山灰、地聚合物和其他高性能硅基材料的合成和利用具有重要价值。碱-硅反应仍然是混凝土的一个主要耐久性问题。随之而来的扩建、裂缝和适用性的丧失，给桥梁、人行道、大坝和其他民用基础设施带来了巨大的维护和重建成本。该项目进行假设驱动的基础研究，以支持在耐久性、延长使用寿命方面的变革性进步，并因此支持易受ASR影响的混凝土基础设施的可持续性和弹性。通过促进与国内和国际机构的合作，该项目为研究生和本科生提供最先进的研究培训，以成为下一代科学家和工程师。该项目的技术部分与教学和推广活动很好地结合在一起，包括：(A)实施以问题为基础的合作学习，以提高本科生的创造性思维和团队合作能力；(B)开发和传播免费互动电子学习模块，使学生、教职员工和实习工程师熟悉先进的材料表征技术；以及(C)促进高中一级的工程学，以吸引和吸引代表不足的学生。

This Faculty Early Career Development (CAREER) project will advance the state of knowledge on deterioration mechanisms, damage mitigation, and prediction of service-life performance for concrete structures susceptible to alkali-silica reaction (ASR). The research approach decouples the three fundamental ASR reactions (silica dissolution, gelation, and swelling) and characterizes the thermodynamic equilibrium and kinetics of each reaction as a function of the chemistry (i.e., species concentrations and interactions) and physics (e.g., temperature, pressure, humidity) of the system. This will significantly clarify the reaction mechanisms and the role of aggregate mineralogy and binder compositions, and can lead to developing more efficient ASR inhibiting admixtures, and admixture delivery methods, applicable to new and existing structures. In addition, new testing and modeling tools are developed for rapid and reliable assessment of the ASR risk and for quantitative prediction of the durability performance of concrete containing potentially reactive aggregates. Finally, ASR in emerging alkali-activated concretes is studied which allows improved reliability and market acceptance of these green materials. The project integrates multi-scale experimentation with multi-scale (geochemical, reactive-transport, and performance prediction) modeling to efficiently achieve these research goals. In addition to advancing the ASR science, the findings could be of substantial value in accelerating the synthesis and utilization of new pozzolans, geopolymers, and other high performance silica-based materials.Alkali-silica reaction continues to be a major durability problem of concrete. The resulting expansion, cracking, and loss of serviceability impose enormous maintenance and reconstruction costs for bridges, pavements, dams, and other civil infrastructure. This project performs hypothesis-driven basic research to support transformative advancements in durability, service-life extension, and as such, sustainability and resiliency of concrete infrastructure susceptible to ASR. Through fostering collaborations with national and international institutes, the project provides state-of-the-art research training for graduate and undergraduate students to become the next generation scientists and engineers. The project's technical components are well integrated with teaching and outreach activities, including (a) implementing cooperative problem-based learning to improve creative thinking and teamwork skills of undergraduate students; (b) development and dissemination of free interactive e-learning modules to familiarize students, faculty, and practicing engineers with advanced materials characterization techniques; and (c) promoting engineering at high school level to attract and engage under-represented students.