Enhancing Infrastructure Resiliency and Sustainability Through Robust Self-Healing Ductile Concrete - A New Paradigm

随着民用基础设施的老化，其功能和安全性的恶化正威胁着美国的经济和生活质量。虽然基础设施老化是不可避免的，但只要改变混凝土设计的范式，退化就不会发生。传统上，混凝土的设计是为了防止损坏。本研究为混凝土设计提供了一种新的途径，它体现了损伤控制和损伤管理。换句话说，混凝土的损坏是允许的，但要控制以保持足够的材料完整性，从而有效地恢复。因此，民用基础设施将更具可持续性和弹性。具体来说，随着时间的推移，混凝土的降解可以通过自我修复不断抵消，从而消除了昂贵的修复周期。在诸如地震或飓风造成的极端负荷下，能力的突然损失是有限的，功能的自我恢复将经济而迅速地进行。该项目的最终目标是通过先进的材料工程来中断美国普遍存在的基础设施恶化和安全问题。除了通过综合研究和教学提高大学教育水平外，该项目还旨在通过外展计划扩大其影响，包括针对50多万高中生的EARTH-2050电视STEM系列节目。该项目的目标是开发一种新的多尺度模型，该模型体现了对控制强大自我修复的物理、化学和机械过程的深刻理解，从而解决了限制此类功能在该领域可靠应用的知识差距。损伤控制和管理方法的成功依赖于延性混凝土的有效开发，该混凝土具有承受超载和控制微裂缝的能力，并随后在没有外部干预的情况下持续修复它们。通过本研究结合新颖的实验技术、解析建模和数值模拟，将产生新的知识，将微裂缝内自愈产物形成的微纳米尺度现象，裂缝关闭和跨裂缝面荷载传递能力恢复的中观尺度现象，以及控制韧性混凝土刚度、强度和延性恢复的宏观尺度现象联系起来。首次获得加载状态下的自愈数据。复杂的自愈行为取决于材料的年龄和成分、损伤程度和环境条件，将通过本研究的多尺度实验和模型来阐明和解决。验证了延性混凝土微裂缝内自形成微复合材料的假设。

With the aging of civil infrastructure, deterioration in their function and safety is threatening the economy and quality of life in the US. While infrastructure aging is inevitable, deterioration is not, provided the paradigm of concrete design is shifted. Traditionally, concrete has been designed for damage prevention. This research is a new approach to concrete design that embodies damage control and damage management. In other words, concrete damage is allowed, but controlled to retain sufficient material integrity that subsequently recovers efficiently. As a result, civil infrastructure will be more sustainable and resilient. Specifically, concrete degradation over time is continuously counteracted by self-healing, eliminating costly cycles of repair. Under extreme loading such as that caused by an earthquake or a hurricane, sudden loss of capacity is limited, and self-recovery of functionality will proceed economically and rapidly. The ultimate goal of this project is to interrupt the ubiquitous infrastructure deterioration and safety concerns in the US through advanced materials engineering. Apart from enhancing education at the university level through integrated research and teaching, this project also aims to broaden its impact through outreach programs, including the EARTH-2050 TV STEM series targeted at over half a million high school students.The objective of this project is to develop a new multi-scale model that embodies deep understanding of the physical, chemical and mechanical processes governing robust self-healing, thus addressing a knowledge gap that has limited the reliable application of such functionality in the field. The success of the damage control and management approach relies on the efficient development of a ductile concrete with the capacity to sustain overloads with controlled microcracks, and to subsequently mend them consistently without external intervention. Through this research combining novel experimental techniques, analytical modeling and numerical modeling, new knowledge will be generated linking micro and nano scale phenomena of self-healing product formation inside microcracks, to meso scale phenomena of crack closure and recovery of load transfer capacity across crack faces, to macro scale phenomena governing the recovery of stiffness, strength and ductility in the ductile concrete. Self-healing data under loaded condition will be obtained for the first time. The complex self-healing behavior that depends on material age and composition, damage degree, and environmental conditions, will be illuminated and resolved through the multi-scale experiments and models derived in this research. The hypothesis of micro-composite self-formation inside microcracks of the ductile concrete will be validated.