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Authors: Yang, kengran
Advisors: White, Claire E
Contributors: Civil and Environmental Engineering Department
Keywords: alkali-activated materials
density functional theory
monte carlo
Subjects: Materials Science
Civil engineering
Issue Date: 2020
Publisher: Princeton, NJ : Princeton University
Abstract: As the cement industry accounts for 5 – 8 % of global anthropogenic CO2 emissions, there is an urgent need to curtail the greenhouse gas emission from the cement industry. The adoption of alternative binding materials, such as alkali-activated materials (AAMs), in place of traditional ordinary Portland cement (OPC) can not only reduce the CO2 emission, but also provide other benefits such as waste valorization. However, our knowledge on the long-term performance of AAMs is considerably limited as there are few in-field applications for service life evaluation. This thesis aims to take on the challenge of resolving the durability of AAMs, which is arguably the most critical roadblock for their commercial scale adoption. Concretely, this thesis centers on the development of a generic computational paradigm, that is, a density functional theory-based coarse-grained Monte Carlo (DFT-CGMC) approach, with the ultimate goal to predict transport properties of AAMs and related materials. This thesis is organized according to the general workflow of the DFT-CGMC approach. Chapter 4 is devoted to modeling of the Gibbs free energy of pair-wise interaction between dissolved molecular species prevalent in AAM and OPC systems via DFT calculation, where the early stage formation mechanisms of calcium-silicate-hydrate (C-S-H) and sodium-based calcium aluminosilicate hydrate (C-(N)-A-S-H) gels, the major binding phase of OPC and AAM, respectively, are proposed. Chapter 5 focuses on augmenting the capability of the DFT-CGMC approach via incorporating calcium species into the model, which is validated by simulating solubility of Ca(OH)2 and comparing the result against experimental data. Chapter 6 centers on a low-calcium variant of AAMs, that is, alkali-activated metakaolin (AAMK). Concretely, the simulated pore structure of AAMK is extracted and compared against pore size distribution data from nitrogen sorption experiment, where semi-quantitative agreement is found. Besides, the pore size distributions of AAMK with different silicon concentrations across length scales are revealed. Lastly, Chapter 7 is an experimental study on the atomic changes of C-(N)-A-S-H gel (from silicate-activated slag) subjected to drying condition via X-ray pair distribution function analysis, serving as a case study showcasing the importance of the knowledge of transport properties of AAMs and related materials.
Alternate format: The Mudd Manuscript Library retains one bound copy of each dissertation. Search for these copies in the library's main catalog:
Type of Material: Academic dissertations (Ph.D.)
Language: en
Appears in Collections:Civil and Environmental Engineering

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