TY - JOUR
T1 - Deterioration mechanism of alkali-activated materials in sulfuric acid and the influence of Cu
T2 - A micro-to-nano structural, elemental and stable isotopic multi-proxy study
AU - Grengg, Cyrill
AU - Gluth, Gregor J.G.
AU - Mittermayr, Florian
AU - Ukrainczyk, Neven
AU - Bertmer, Marko
AU - Guilherme Buzanich, Ana
AU - Radtke, Martin
AU - Leis, Albrecht
AU - Dietzel, Martin
PY - 2021/4
Y1 - 2021/4
N2 - 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.
AB - 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.
KW - Alkali-activated cement
KW - Corrosion
KW - Durability
KW - Microstructure
KW - Modelling
UR - http://www.scopus.com/inward/record.url?scp=85100051394&partnerID=8YFLogxK
U2 - 10.1016/j.cemconres.2021.106373
DO - 10.1016/j.cemconres.2021.106373
M3 - Article
AN - SCOPUS:85100051394
SN - 0008-8846
VL - 142
JO - Cement and Concrete Research
JF - Cement and Concrete Research
M1 - 106373
ER -