Bioinspired Layered Geopolymer Composites

Harmal, Anass

Etd

Bioinspired Layered Geopolymer Composites

Public Deposited

Geopolymer cement has been at the forefront of climate conscious research in construction materials. This is resulting from the material exhibiting equivalent mechanical behavior to Ordinary Portland Cement, at much lower levels of emissions. Geopolymer's implementation in the construction industry is, however, limited by several factors: poor understanding of the geopolymerization process, rapid coagulation, no effective control over rheology and setting/curing time, and very high brittleness. This dissertation is focused on the latter issue, prescribing new ways to augment the toughness of geopolymer composites beyond the current state of the art, without compromising strength. To concretize this goal, bioinspired design, drawing from biological mineralized layered composites, is utilized. Specifically, a layered brick-and-mortar structure is considered, where geopolymer is the brick phase, and ductile polymers are considered as the mortar phase. First, this work focuses on exploring the synthesis of bioinspired layered geopolymer composites, reporting the effect of the soft phase stiffness on the performance of the composites, and uncovering underlying toughening mechanisms at the macro- and micro-scales. Second, important morphological parameters such as the aspect ratio and overlap, identified in biological layered composites, are examined to show their effect on the mechanical behavior and toughening mechanisms of bioinspired layered geopolymer composites. Third, given the vast design space of the synthesized composites, simulation is utilized to more efficiently explore this design space. A simulation based on Lattice Spring Modeling (LSM) is formulated and used to explore the effect of the stiffness and strength of the soft phase and interface on the mechanical performance of bioinspired layered geopolymer composites.

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