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Mechanisms of Biogenic Acid Degradation of Low-Calcium Alkali-Activated Cements
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Mechanisms of Biogenic Acid Degradation of Low-Calcium Alkali-Activated Cements. |
| 개인저자 | Gevaudan, Juan Pablo. |
| 단체저자명 | University of Colorado at Boulder. Civil, Environmental, and Architectural Engineering. |
| 발행사항 | [S.l.]: University of Colorado at Boulder., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 154 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-04B. Dissertation Abstract International |
| ISBN | 9781088375679 |
| 학위논문주기 | Thesis (Ph.D.)--University of Colorado at Boulder, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-04, Section: B.
Advisor: Srubar, Wil V., III. |
| 이용제한사항 | This item must not be sold to any third party vendors. |
| 요약 | Alkali-activated cements (AACs) are alternative cements with the potential to counter durability concerns associated with the use of ordinary portland cement (OPC), as further discussed in Chapter I. As a result of their superior durability, AACs have been proposed as material solutions to microbial-induced concrete corrosion-a pervasive durability challenge concerning the acid degradation of wastewater infrastructure, as explained in Chapter II. The main objective of this dissertation was to investigate the effect of supplementary ions (i.e., Cu, Co, Si, Mg, Fe) on the mechanisms of acid degradation (i.e., dealumination) and relevant material properties of low-calcium AACs. Chapter III investigates the acid degradation of low-calcium AAC materials supplemented with heavy metals (i.e., Cu, Co), known for their anti-microbial properties. Results from this work demonstrate that heavy metals improve the acid resistance of AACs and explicitly elucidate the role of hydronium ions (H3O+), which penetrate past the visually observable corrosion layer and induce cationic exchange, resulting in electrophilic degradation of the Si-O-Al bonds with concomitant beneficial cationic dissolution of minerals. In Chapter IV, the effect of processing conditions on material porosity was correlated to short-term mineralogical stability of low-calcium AACs. Results indicate that sodium content dictates the short-term mineralogical stability and, hence, microstructural formation of certain aluminosilicate zeolitic minerals. These can either decrease (faujasite formation) or increase (zeolite A formation) permeable porosity, substantiating the importance of favorable versus non-favorable zeolite formation. Secondly, Chapter V investigates the effect of an iron-rich mineral admixture (i.e., hematite) on the acid resistance of low-calcium AACs. Results indicate that iron-rich mineral admixtures improve AAC acid resistance by increasing micro-sized porosity, while also inducing increases to Fe:Al ratios, which are correlated with compressive strength and microstructure (Si-O-Al) preservation. Thirdly, to contrast with hematite, a mineral-rich in heavy metal (i.e., Fe), Chapter VI investigates the effect of a light metal, magnesium-rich mineral admixture (i.e., brucite). Results indicate that addition of brucite improves the acid resistance of low-calcium AACs by increasing the pH buffering capacity of the material. Moreover, observed Mg:Al ratio increases after exposure indicates a spatial-temporal cation re-arrangement, which preserves the micro- and nano-scale porosity. |
| 일반주제명 | Architectural engineering. Engineering. |
| 언어 | 영어 |
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