Development of Concrete Damage-Flow Rate Correlation using Integrated Structural Testing and X-Ray Tomography Tara C. Hutchinson (PI)1 and Falko Kuester2
Concrete is by far the most widely used building material in the United States, with extensive use in the construction of our Nation's buildings, highways, tunnels, water supply and sewage systems and other infrastructure. The strong dependency of the service life of concrete on its transport properties means that investigations, which are geared at studying this internal microstructure, should link these transport properties to damage states of the concrete component. In this proposal, we seek to advance our fundamental knowledge of the damage characteristics of reinforced concrete members and link these characteristics with a fundamental transport property. Although many transport mechanisms are certainly of interest, we select the air permeability as the transport mechanism of interest, as a first step towards other mechanisms and to lay the foundation of the methodology proposed. Our proposed approach includes integrating structural testing of scaled specimens, X-ray computed tomography (CT) imaging, and air flow rate experiments of 20 model reinforced concrete panel-style specimens. Specimens are subjected to uniaxial and biaxial loading conditions, and include parameter variations of geometry (aspect ratio and panel thickness), material details (reinforcing steel ratio and concrete strength), and loading details (axial load and loading protocol). Numerical evaluation of permeability and leakage rate formula available in the literature as well as finite element simulations of the experimental specimens will be conducted in an overall effort to develop design guidance regarding the damage leakage rate correlation of reinforced concrete elements.
Intellectual Merits - The intellectual merits of this include developments in experimental methods and results, fundamental advancements in the understanding of damage-transport relations of reinforced concrete, and practical impacts on the design industry. The datasets available from this work (both image and numerical data) will spur new discoveries of the internal damage distribution of this complex, composite material. Ultimately, this work will result in design guidance, which accounts for the degrading permeability of concrete. Progress overall in concrete research will lead to a reduction in the cost of new infrastructure and rehabilitation of existing structures, while increasing the service life of one of our most abundantly used construction materials.
Broader Impacts - Broader technical impacts include the advancement of our understanding of concrete as a fundamental building material, thus leading to improved designs, with more reliable estimates of properties and hence performance. The acquisition and implementation of the X-ray CT system will have long reaching impacts on the research activities at UC Irvine, for its students and faculty, as well as the local academic community interested in using the system. The educational impacts of the data, images and numerical data, provide a natural haven for reaching all ranges of interested students, from the general public to K-12, and especially the diverse and/or minority student. The natural digital nature of this works makes it viable for Internet dissemination, and we plan to design a special web site (we termed ConcretePedia) devoted to disseminating these image datasets in VRML format (for the general public to interactively view and learn). This work also actively engages industrial and government collaboration, which helps facilitate its impact to the engineering public.
