Investigations on alkali-silica reaction products using Raman spectroscopy

• Autores: M.E. Krüger, V. Thome, H. Hilbig, M. Kaliwoda, D. Heinz
• Localización: Materiales de construcción, ISSN 0465-2746, Vol. 72, Nº. 346, 2022 (Ejemplar dedicado a: Online First; e287)
• Idioma: inglés
• Enlaces
  • Texto completo
• Resumen

  • 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.