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（Career）项目将推进对易受碱-硅反应（ASR）影响的混凝土结构的退化机制、损伤缓解和使用寿命性能预测的知识状态。该研究方法解耦了三种基本的ASR反应（二氧化硅溶解、凝胶化和膨胀），并将每个反应的热力学平衡和动力学表征为系统的化学（即物质浓度和相互作用）和物理（如温度、压力、湿度）的函数。这将极大地阐明反应机制以及骨料矿物学和粘结剂组成的作用，并有助于开发更有效的ASR抑制外加剂，以及适用于新结构和现有结构的外加剂输送方法。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反应性骨料的混凝土的耐久性。最后，研究了新兴碱活化混凝土中的ASR，从而提高了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、反应输运和性能预测）建模相结合，以有效实现这些研究目标。除了推进ASR科学之外，这些发现在加速新型火山灰、地聚合物和其他高性能硅基材料的合成和利用方面可能具有重大价值。碱-硅反应一直是混凝土耐久性的主要问题。由此产生的膨胀、开裂和丧失可用性给桥梁、路面、水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，以支持耐久性、使用寿命延长以及易受ASR影响的混凝土基础设施的可持续性和弹性方面的变革性进步。通过促进与国内和国际研究所的合作，该项目为研究生和本科生提供最先进的研究培训，使他们成为下一代科学家和工程师。该项目的技术部分与教学和外展活动很好地结合在一起，包括(a)实施基于问题的合作学习，以提高本科生的创造性思维和团队合作技能；(b)开发和传播免费的交互式电子学习模块，使学生、教师和执业工程师熟悉先进的材料表征技术；(c)促进高中水平的工程，以吸引和吸引代表性不足的学生。

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.