Open AccessInvestigations on alkali-silica reaction products using Raman spectroscopy
Author(s) -
Miriam E. Krüger,
Volker Thome,
Harald Hilbig,
Melanie Kaliwoda,
D. Heinz
Publication year - 2022
Publication title -
materiales de construcción
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.539
H-Index - 30
eISSN - 1988-3226
pISSN - 0465-2746
DOI - 10.3989/mc.2022.15621
Subject(s) - raman spectroscopy , alkali–silica reaction , alkali metal , silica gel , molar ratio , spectroscopy , materials science , alkali–aggregate reaction , chemical engineering , calcium , nuclear magnetic resonance spectroscopy , sodium , inorganic chemistry , chemistry , organic chemistry , catalysis , nanotechnology , composite material , aggregate (composite) , metallurgy , physics , engineering , quantum mechanics , optics
The alkali-silica reaction (ASR) remains a major challenge regarding the durability of concrete structures. The reaction mechanism is not sufficiently understood owing to the difficulty in characterizing the structure of the alkali-silica reaction gel (ASR gel) in concrete. Synthetic ASR gels with different compositions, i.e. Na/Si and Ca/Si molar ratios, were synthesized and analysed by Raman spectroscopy and, for comparison, 29Si NMR spectroscopy. The results show that higher Na/Si ratios increase the number of non-bridging oxygens in the gel structure, thus leading to a decrease in the degree of cross-linking. With increasing calcium content of the sodium-calcium silica gel, the structure tends towards that of C-S-H phases. Raman spectroscopy is a promising method to characterise synthetic ASR gels and provide new information on the effect of alkalis on the gel structure.