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Journal of Materials Science

, Volume 29, Issue 21, pp 5524–5528 | Cite as

The setting of gypsum plaster

Part II The development of microstructure and strength
  • A. J. Lewry
  • J. Williamson
Papers

Abstract

The setting process of gypsum plasters has been followed using strength testing, acoustic techniques and scanning electron microscopy. Gypsum plasters were found to set in three stages: formation of the calcium sulphate dihydrate crystal matrix followed by relief of internal stress, and finally evaporation of excess water. The α-calcium sulphate hemihydrate set faster than the β-form, giving a higher initial and final set strength. The set α-plaster consisted of relatively short stubby dihydrate needles with a greater degree of intercrystalline bonding, resulting in greater strength. The microstructure of set α-plaster appeared to be the result of a slower precipitation rate of dihydrate during the hydration reaction of hemihydrate.

Keywords

Gypsum Internal Stress Dihydrate Strength Testing Calcium Sulphate 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman & Hall 1994

Authors and Affiliations

  • A. J. Lewry
    • 1
  • J. Williamson
    • 2
  1. 1.Building Research EstablishmentWatfordUK
  2. 2.Materials DepartmentImperial CollegeLondonUK

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