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Characterization and modeling mass transport in cracked concrete
For reliable prediction of the durability and service-life of concrete structures, it is important to model how moisture and aggressive agents (e.g., salts, CO2) penetrate into and degrade concrete. Since concrete often cracks in response to restrained shrinkage and service loads, it is also important to account for the effect of cracks in increasing the penetrability of concrete. In this project, the multi-mechanistic transport of moisture and solutes in a cracked porous media is modeled using FEA while the transport properties of cracks and the matrix are characterized experimentally. Transport properties are quantified based on crack geometry (i.e., width, roughness and tortuosity) using permeability cells, impedance spectroscopy, X-ray tomography (CAT), surface profilometry, and digital image analysis.

Engineering and life-cycle assessment of recycled glass-based concretes
Approximately 20% of glass placed in recycle bins in the U.S. end up in stockpiles and landfills and are never recycled. This is due to prohibitive transportation costs from recycling points to glass melting factories and poses major challenges for many states and municipalities. Our research goal is to utilize this material as a pozzolan or fine aggregate in concrete. Specifically the research is focused on developing novel methods to mitigate alkali-silica reaction (ASR) and instead promote a pozzolanic reaction by soda-lime glass. The mechanisms of ASR and its mitigation by fly ash and glass powder is studied. Application of several chemical activation techniques to boost the pozzolanic reactivity is investigated. To evaluate the environmental impact of the resulting glass-based concretes, comprehensive life-cycle assessment is performed in collaboration with Carnegie Mellon University.

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Predicting early-age cracking in restrained concrete elements using computational fracture mechanics
In restrained concrete elements (e.g., bridge decks, pavements) the early-age thermal and hygral shrinkage of concrete leads to stress development and cracking. These cracks accelerate the deteriorations and shorten the service-life of structures. This project employs FEA-based stress and fracture mechanics simulations to predict distress potentials and crack evolution in concrete. As a result, a set of "Design for Durability" tools are developed to assist engineers in proper design of concrete mixtures and selection of temperature and shrinkage steel to prevent early cracking in restrained concrete members.