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，其功能和安全的恶化正在威胁美国的经济和生活质量。虽然基础设施老化是不可避免的，但如果具体设计的范式发生变化，恶化就不会。传统上，混凝土是为了防止损坏而设计的。本研究是一种体现损伤控制和损伤管理的混凝土设计新方法。换句话说，混凝土的损伤是允许的，但要加以控制，以保持足够的材料完整性，从而有效地恢复。因此，民用基础设施将更加可持续和更具弹性。具体地说，随着时间的推移，混凝土的退化会不断被自我修复所抵消，从而消除了昂贵的修复周期。在极端负荷下，如地震或飓风造成的负荷，突然丧失的能力是有限的，功能的自我恢复将经济而快速地进行。该项目的最终目标是通过先进的材料工程，打破美国无处不在的基础设施恶化和安全担忧。除了通过综合研究和教学加强大学层面的教育外，该项目还旨在通过外联项目扩大其影响，包括针对50多万高中生的地球-2050电视STEM系列节目。该项目的目标是开发一个新的多尺度模型，体现对支配强大自我修复的物理、化学和机械过程的深刻理解，从而解决限制此类功能在该领域可靠应用的知识差距。损害控制和管理办法的成功有赖于有效地发展延性混凝土，使其能够承受受控微裂缝的超载，并随后在没有外部干预的情况下始终如一地进行修补。通过将新的实验技术、分析模型和数值模拟相结合，将微裂缝内部自愈产物形成的微观和纳米尺度现象，到裂缝闭合和裂缝面间荷载传递能力的恢复的细观尺度现象，以及控制延性混凝土的刚度、强度和延性的宏观尺度现象，都将产生新的知识。首次获得负载条件下的自愈数据。复杂的自愈行为依赖于材料的年龄和成分、损伤程度和环境条件，将通过本研究中建立的多尺度实验和模型来阐明和解决。延性混凝土微裂缝内部的微复合自形成假说将得到验证。

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.