Deterioration mechanism of alkali-activated materials in sulfuric acid and the influence of Cu: A micro-to-nano structural, elemental and stable isotopic multi-proxy study

Cyrill Grengg*, Gregor J.G. Gluth, Florian Mittermayr, Neven Ukrainczyk, Marko Bertmer, Ana Guilherme Buzanich, Martin Radtke, Albrecht Leis, Martin Dietzel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

In this study, a multi-proxy approach combining 29Si, 27Al and 1H MAS-NMR, FEG-EPMA, XANES at the Cu K-edge and XRD analytics with hydrochemical tools such as ICP-OES analyses, oxygen-isotope signatures, and thermodynamic modelling was applied to K-silicate-activated metakaolin specimens - with and without CuSO4·5H2O addition - exposed to sulfuric acid at pH = 2 for 35 days. The results revealed a multistage deterioration mechanism governed by (i) acid diffusion, (ii) leaching of K-A-S-H, (iii) microstructural damage related to precipitation of expansive (K,Ca,Al)-sulfate-hydrate phases (iv) complete dissolution of the K-A-S-H framework, (v) and formation of silica gel in the outermost corroded regions. Copper ions were mainly located in layered spertiniite-chrysocolla-like phases in the as-cured materials. The results demonstrate an overall negative effect of Cu addition on chemical material durability, implying that the reported higher durability of Cu-doped AAM in biocorrosion environments can be best explained by bacteriostatic effects.

Original languageEnglish
Article number106373
JournalCement and Concrete Research
Volume142
DOIs
Publication statusPublished - Apr 2021

Keywords

  • Alkali-activated cement
  • Corrosion
  • Durability
  • Microstructure
  • Modelling

ASJC Scopus subject areas

  • Building and Construction
  • Materials Science(all)

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