Synthesis and Multi-Scale Mechanical Characterization of CSH

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This research project aims at understanding the nature of calcium-silicate-hydrate (C-S-H) as the main cement hydration product and its responsibility in the strength and fracture of cement based composites. The recent fracture of oil well in the Gulf of Mexico and its associated environmental impact necessitate a thorough understanding of the significance of cement curing regimes, including high pressure and temperature on the microstructure of cement hydration products and the influence of that microstructure on the mechanical, impact and fracture resistance of cement. The goal of the research is to investigate the fundamental process for synthesis of C-S-H, to correlate its nano and microstructure features, and to further understand its mechanical characteristics including creep, impact strength and fracture toughness. The scope focuses on how the nano and microstructural features of C-S-H are altered when the calcium-silicate (C/S) ratio is changed (ratios ranging from 0.6 to 1.5) and when the hydration process occurs under different combinations of temperatures and pressures. By testing C-S-H synthesized under varying curing conditions, we will understand the significance of hydration conditions on silicate polymerization and water structure of C-S-H and how C-S-H nanostructure affects its creep, fracture and impact strength. Funds will be used to support graduate and undergraduate students in University of New Mexico (UNM): a minority serving institution. This work will fill a major knowledge gap as most researchers working in the field have focused on the chemical and microstructural nature of C-S-H and very limited research has provided information on the mechanical characteristics of C-S-H. If successful, we will reveal some major mechanical characteristics of C-S-H including creep, fracture and impact strength. Successful research investigation shall lead to necessary changes in cement manufacturing to produce impact-tolerant cement-based composites.