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.
