Effect of aluminum on the structure of synthetic alkali-silica gels

Miriam E. Krüger, Anne Heisig, Harald Hilbig, Henrik Eickhoff, Detlef Heinz, Alisa Machner

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


The use of supplementary cementitious materials, such as fly ash, ground-granulated blast furnace slag (GGBFS), or metakaolin, in cement and concrete, is known to increase the amount of aluminum in the system and enhance its resistance against the alkali-silica reaction (ASR). It is, however, not yet sufficiently understood to what extent aluminum affects the structure of alkali-silica gels and how such a potential incorporation of aluminum contributes additionally to the beneficial effect of aluminum on ASR. In this study, various alkali-silica gels with different aluminum content were synthesized and structurally characterized. The results show that aluminum can be incorporated into the alkali-silica gel structure in four- and six-fold coordination, thus leading to a structural change. The incorporation of aluminum may increase the connectivity and the degree of polymerization within the gel framework. Based on the results, a 3D structural model for an aluminum-containing alkali-silica gel was created.

Original languageEnglish
Article number107088
JournalCement and Concrete Research
StatePublished - Apr 2023


  • Al NMR
  • Alkali-silica gel
  • Alkali-silica reaction (ASR)
  • Aluminum in ASR gels
  • Concrete
  • FTIR
  • Si NMR
  • Supplementary cementitious materials (SCM's)
  • TGA
  • XRD


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