Interface Engineering of Fiber Reinforced Calcium-based Composites

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The use of discontinuous and randomly oriented nano/microfibers (steel, carbon, polymer) as reinforcements in calcium-based materials for civil and biomedical applications has received increasing attention due to their promising potential for superior structural and multifunctional composites. The interface between the fibers and the matrix plays a vital role in material performance and must be accurately characterized to effectively design materials. The goal of this research project is to understand reinforcement mechanisms in fiber reinforced calcium-based composites. Fundamental understanding of key features of fiber reinforcements will enable better material design and fabrication strategies. The broader impacts are twofold. Civil engineering applications: Advanced materials that extend the life of civil infrastructure, reduce maintenance costs, and enhance safety and sustainability will save billions of tax dollars a year and have many magnified indirect effects on society. Biomedical applications: Advanced biomimetic materials will provide more effective medical treatments. The educational component will introduce high school students to the intriguing science of the very small and will develop a graduate level course module on material durability.The goal is to fundamentally understand the molecular structure and dynamics at the fiber-solid-liquid interfaces that control reinforcement mechanisms in fiber reinforced calcium-based materials with an emphasis on determining the nature of the interface and how it relates to interfacial mechanical behavior. The focus is on the molecular to nanoscale and the chemo-mechanical interactions at reinforcement matrix interfaces. Molecular dynamics modeling and experimental characterizations of the structure and dynamics of the interfaces will be integrated to (i) elucidate the interfacial interactions between fiber surfaces, calcium-bearing solid phases, and surrounding liquid phases, (ii) quantify and relate the effect of the chemical structure to the mechanical properties of reinforcement matrix interfaces, and (iii) formulate molecular dynamics-informed interface cohesive traction-separation relationships that connect the molecular scale to the micro-continuum scale at interfaces. The research will (i) provide a molecular to nanoscale picture necessary to achieve improved engineering properties, (ii) make advances in relating chemistry and mechanical properties at interfaces, and (iii) bridge the gap between nano-mechanics and micro-mechanics at interfaces.