Effect of calcium on dissolution and precipitation reactions of amorphous silica at high alkalinity

Hamed Maraghechi, Farshad Rajabipour, Carlo G. Pantano, William D. Burgos

Research output: Contribution to journalArticlepeer-review

69 Scopus citations

Abstract

A better understanding of silica dissolution-precipitation reactions at high pH aqueous solutions allows for promotion of favorable (e.g.; pozzolanic) reactions and mitigation of deleterious (e.g.; alkali-silica) reactions in concrete. In this paper, the kinetics and products of silica glass dissolution are studied as a function of solution pH, temperature, and availability of calcium. It was observed that dissolution rate versus time increases linearly with pH and reaches a maximum at pH = 14, with slower dissolution at higher alkalinities. In solutions with similarly high pH, but saturated with portlandite, glass dissolution is significantly slower. This is due to formation of a dense, low porosity, and strongly bonded C-S-H layer on the surface of glass, which serves as a barrier against diffusion of OH- and alkali ions towards the substrate glass. This protective layer forms only when Ca is abundant and portlandite saturation can be maintained on a local scale.

Original languageEnglish (US)
Pages (from-to)1-13
Number of pages13
JournalCement and Concrete Research
Volume87
DOIs
StatePublished - Sep 1 2016

All Science Journal Classification (ASJC) codes

  • Building and Construction
  • Materials Science(all)

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