Sulfuric acid degradation of alkali-activated metakaolin cements supplemented with brucite

This study investigated the effect of alkali content (Na:Al = 0.86 and 1.39) and brucite (i.e., Mg(OH)2) mineral addition on the sulfuric acid resistance of alkali-activated metakaolin (i.e., geopolymers). Geopolymers consist primarily of a sodium-stabilized aluminosilicate hydrate (N-A-S-H) framework. Results demonstrate that higher alkali contents and brucite addition improve the acid resistance of N-A-S-H, as evidenced by reduced dealumination and Si and Na leaching upon exposure to acid. These results are mechanistically explained by increased retention of Mg+2 within the microstructure and increased Mg–Al interaction upon acid exposure. Higher Mg+2 retention and increased Mg–Al coupling together provide empirical evidence of polyvalent cationic stabilization—a mechanism involving polyvalent cations (e.g., Mg+2) that stabilize the N-A-S-H binder by arresting acid-induced electrophilic attack. Results further illustrate that brucite addition, especially at high-alkali content formulations, reduces micro-scale porosity while increasing the proportion of gel pores (<5 nm), which suggests that increased tortuosity of gel pores may aid in Mg+2 retention and promote the increased Mg–Al coupling observed herein.

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Work Title Sulfuric acid degradation of alkali-activated metakaolin cements supplemented with brucite
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Open Access
Creators
  1. Juan Pablo Gevaudan
  2. Zoey Craun
  3. Wil V. Srubar
License In Copyright (Rights Reserved)
Work Type Article
Publisher
  1. Cement and Concrete Composites
Publication Date August 1, 2021
Publisher Identifier (DOI)
  1. https://doi.org/10.1016/j.cemconcomp.2021.104063
Deposited November 16, 2021

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  • Added Creator Juan Pablo Gevaudan
  • Added Creator Zoey Craun
  • Added Creator Wil V. Srubar
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