Material Design and Durability Characterization of “Non-Brittle” Geopolymer
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Geopolymers are inorganic polymers that have resulted in wide scientific interest and broad development of applications. They possess intriguing characteristics that bridge polymer science and ceramics. Many inexpensive earth-abundant minerals and industrial wastes can form geopolymers; this diversity enables a large palette of suitable ingredients to be selected to achieve specific properties, offering a variety of possibilities for material design. The microstructure of fully reacted K-poly(sialate-siloxo) type geopolymer is nanoporous and sponge-like, consisting of nanoparticulates ranging from 5-15 nm separated by nanopores on the order of 3 to 10 nm. The nanoparticulates features dimensions suggesting a macromolecule of definite size. Such characteristic microstructure of geopolymers leads to their unique chemical and mechanical features. While geopolymers provide great potential for applications in many fields, their long-term performance remains unaddressed. Also, the inherent brittleness of geopolymers limits their durability; inevitable cracking can be the result of one or a combination of mechanical and environmental factors. In this thesis, we aim at designing a new category of geopolymers with a “non-brittle” behavior, and understanding the mechanical and chemical responses of geopolymer to various environmental conditions including shrinkage, elevated temperature, water permeation, and corrosion of embedded steel.