Nanoscale Characterization of Expansion Due to Delayed Ettringite Formation

本研究的主要目的是研究晚期钙矾石形成的纳米和微观机制，以及这些机制与混凝土材料中宏观尺度膨胀的关系，从而为晚期钙矾石形成造成的损害提供可能的缓解策略。本研究将研究晚期钙矾石形成及其膨胀开裂过程中，反应物和产物的化学和物理结构，以及孔隙结构的演化。通过使用纳米压痕和残余应力分析等分析技术改进现有模型，可以更彻底地了解晶体压力对微观结构的影响。混凝土是世界上使用最广泛的工程材料，但在许多方面仍然知之甚少。众所周知，钙矾石会导致混凝土开裂，防止钙矾石的延迟形成将显著提高美国和国外基础设施的寿命。教育活动将包括前往当地的初中和高中，提供动手实验，让学生们真实地了解工程是如何成为现代世界的重要组成部分。当地的小学团体将被邀请到校园参加田纳西理工大学的实践学习经验。it’这是STEM中心。除了教育活动外，在项目结束时还建议举办残余应力分析讲习班，向其他水泥和混凝土研究人员传播田纳西理工大学在这一领域的强大背景；因此，超越了传统的K-12教育。

The primary objective of this research is to investigate the nano- and micro-scale mechanisms of late age ettringite formation and how these mechanisms relate to macro-scale expansion in concrete materials, enabling possible mitigation strategies for damage due to the late age formation of ettringite. This research will examine the chemical and physical structure of the reactants and products, as well as the pore structure evolution, involved in the process of late age ettringite formation and subsequent expansion and cracking. A more thorough understanding of the crystalline pressures induced on the microstructure will result by refining existing models with analytical techniques such as nanoindentation and residual stress analyses.Concrete is the most widely used engineering material in the world, yet is still poorly understand in many regards. The prevention of delayed ettringite formation, which is known to cause concrete cracking, would significantly improve the infrastructure life span of the United States and abroad. Educational activities will include traveling to local middle and high schools to provide hands-on experiments that give the students a real-life view of how engineering is an important part of the modern world. Local primary school groups will be invited to campus to participate in hands-on learning experiences at Tennessee Tech?s STEM Center. In addition to the educational activities, a residual stress analysis workshop is proposed at the end of the project to disseminate the strong background in this field at Tennessee Tech to other cement and concrete researchers; thus, expanding beyond traditional K-12 outreach.