AUTOGENOUS SHRINKAGE OF CONCRETE: A BALANCE BETWEEN AUTOGENOUS SWELLING AND SELF-DESICCATION

Autogenous shrinkage of concrete is the deformation occurring at constant temperature with no moisture exchange with the environmental medium. The driving force of autogenous shrinkage of concrete is the change in the capillary pressure induced by self-desiccation in its cement matrix. Self-desiccation is caused by the balance between the absolute volume reduction (chemical shrinkage) and the building up of the capillary network. This article reports on a study undertaken to quantify the influence of the cement characteristics on the chain of mechanisms leading from hydration to autogenous deformations. Four parameters were selected: for clinker, the amount of C3A and free lime and the SO3/K2O ratio; and for cement, the fineness. The study included 16 cements prepared at the laboratory from pure raw materials which were tested on parameters including: setting time, suspension-solid transition, hydration kinetics through isothermal calorimetry and nonevaporable water, chemical shrinkage, evolution of relative humidity, capillary porosity and autogenous shrinkage. Results showed that initial autogenous shrinkage should be considered as a balance between the self-desiccation and an initial swelling phase. The creation of the early hydrated products results in an autogenous swelling phenomenon that decreases with time. The sulfate-to-alkali ratio of the clinker and the amount of free lime seems to change the intensity of this swelling phase.

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    Elsevier

    The Boulevard, Langford Lane
    Kidlington, Oxford  United Kingdom  OX5 1GB
  • Authors:
    • Barcelo, L
    • Moranville, M
    • Clavaud, B
  • Publication Date: 2005-1

Language

  • English

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Filing Info

  • Accession Number: 00988994
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 18 2005 12:00AM