Durability of short carbon fiber reinforced cement-based materials during exposure to chemical attack

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Abstract - Durability of short carbon fiber reinforced cement-based materials during exposure to chemical attackF. SanchezConcrete degradation is a large burden on the US economy. Composite materials have been advocated as a means to break this cycle of deterioration in aging infrastructure based on demonstrated corrosion resistance, control of crack propagation, and increased strength-to-weight ratios. Among these composite materials, short carbon fiber reinforced concrete has shown additional property enhancements including increased electromagnetic interference shielding, capability of sensing internal strain, self-monitoring of mechanical damage, sensing of temperature changes, and thermal actuation. Due to the appealing properties of these multifunctional materials and the critical role that they can play in improving infrastructural health and function, it is important to gain a better understanding of their long-term durability. The goal of this research is to investigate (i) the effect of exposure to chemical attack on the microstructure and morphology of carbon fiber reinforced concrete and (ii) how microstructural and morphological changes at the interface between the carbon fibers and the cementitious material in turn affect the macro scale mechanical and physical properties of the material, including strength, electrical conductivity, and durability. State-of-the-art physical (surface area, microporosity, 3-D imaging of pore structure, and advanced thermal analysis) and chemical (elemental composition and solid phase mineralogy and morphology) techniques and traditional durability testing will be used to (i) characterize the surface of the carbon fibers under different conditions ("as-received," after surface treatment, and during hydration reaction), (ii) quantify and relate the physical and chemical changes of the carbon fiber-cement interface and of the bulk cement paste during decalcification to observed macro scale properties. The proposed research will mark a critical step towards understanding how to further enhance the performance of carbon fiber reinforced cement-based materials. Educational outreach will provide an increased appreciation of civil engineering study and research and its benefits to society to primary education teachers and students through partnership with local educators and education experts and will involve development of age-appropriate teaching modules for inner-city, middle and high school students.