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The '''alkali-carbonate reaction''' is a process suspected for the degradation of concrete containing dolomite Construction aggregate|aggregate Alkali from the cement might react with the dolomite crystals present in the aggregate inducing the production of brucite (MgOH)2 and calcite (CaCO3) This mechanism was tentatively proposed by Swenson and Gillott (1950) and may be written as follows:
CaMg(CO3)2 + 2 NaOH —> CaCO3 + Na2CO3 + Mg(OH)2

Brucite (Mg(OH)2) could be the responsible of the volumetric expansion after de-dolomotisation of the aggregate

References

  • Swenson EG (1957) A reactive aggregate undetected by ASTM test ASTM Bulletin No. 226 pp. 48–50
  • Swenson EG (1957) Cement-aggregate reaction in concrete of a Canadian bridge ASTM Proceedings 57: 1043–1056