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Materials and Structures

, 37:522 | Cite as

Moisture distribution in drying ordinary and high performance concrete cured in a simulated hot dry climate

  • P. F. de J. Cano-Barrita
  • B. J. Balcom
  • T. W. Bremner
  • M. B. MacMillan
  • W. S. Langley
Article

Abstract

Adequate moisture is very important during early age of portland cement concrete. The Single Point Magnetic Resonance Imaging technique was used to study the effects of various lengths of moist curing, and the use of curing compound, on the amount and distribution of evaporable water during drying of ordinary and high performance concrete. The specimens subjected to six different curing regimes, were cast in triplicate for a total of 72. After moist curing at 38°C, the specimens were subjected to uniaxial drying in an environmental chamber at 38°C and 40% relative humidity that simulated hot dry climate conditions. As the specimens were drying, Magnetic Resonance Imaging was used to study the evaporable water distribution, non-destructively and with millimetric resolution. The Magnetic Resonance Imaging profiles indicated a reduced moisture loss with increasing length of moist curing. Extended moist curing was especially beneficial for the two self-compacting concrete mixtures, particularly for the cover concrete. In all mixtures the use of curing compound was only marginally better than one day moist curing, but was significantly better than air curing, particularly for the cover concrete. The moisture diffusivity was evaluated from the transient moisture distribution profiles using the Boltzmann transformation method. The results indicated a strong dependence of the moisture diffusivity on the moisture content when above 80% saturation, whereas below this value it remains almost constant. The moisture diffusivity is significantly reduced with increased moist curing period.

Keywords

Silica Fume Cover Concrete Moisture Diffusivity High Performance Concrete Evaporable Water 
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.

Résumé

Le maintien d'un taux d'humidité adéquat est très important pour un béton frais. La technique d'imagerie à résonance magnétique (à un point) est utilisée pour étudier les effets de la longueur de la période de mûrissement à l'humidité et de l'utilisation de produits de mûrissement sur la quantité et la distribution de l'eau évaporable lors du séchage du béton ordinaire et du béton à haute performance. Les échantillons aussjettis à six différents régimes de mûrissement, sont moulés en trois exemplaires pour un total de 72. Après mûrissement à l'humidité à une température de 38°C, les échantillons sont soumis à un séchage uniaxial dans un environnement contrôlé à une température de 38°C et une humidité relative de 40% pour simuler des conditions climatiques chaudes et sèches. Lors du séchage, une technique non-destructive, par imagerie à résonance magnétique, est utilisée pour étudier la distribution d'eau évaporable avec une résolution au millimètre près. Les profils obtenus par imagerie à résonance magnétique indiquent une réduction de la perte d'humidité lorsque de la période de mûrissement à l'humidité est prolongée. Un mûrissement à l'humidité prolongé est bénéfique spécialement pour les deux mélanges de bétons auto-plaçants, particulièrement pour le béton de surface. Pour les mélanges étudiés, l'utilisation de produits de mûrissements ne montre qu'une faible amélioration par rapport au mûrissement à l'humidité pendant un jour, mais offre un net avantage par rapport au mûrissement à l'air, particulièrement pour le béton de surface. Le coefficient de diffusion de l'humidité est évalué à partir du profil transitoire de la distribution de l'humidité au moyen de la transformation de Boltzmann. Les résultats indiquent que le coefficient de diffusion de l'humidité dépend fortement du degré d'humidité lorsque celui-ci est supérieur à 80% du degré d'humidité à la saturation. En deçà de ce niveau, il est presque constant. Le coefficient de diffusion de l'humidité diminue significativement avec l'allongement de la période de mûrissement.

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Copyright information

© RILEM 2004

Authors and Affiliations

  • P. F. de J. Cano-Barrita
    • 1
  • B. J. Balcom
    • 2
  • T. W. Bremner
    • 3
  • M. B. MacMillan
    • 2
  • W. S. Langley
    • 4
  1. 1.CIIDIR OaxacaNational Polytechnic Institute of MexicoMéxico
  2. 2.MRI Centre, Department of PhysicsUniversity of New BrunswickFrederictonCanada
  3. 3.Civil EngineeringUniversity of New BrunswickFrederictonCanada
  4. 4.W. S. Langley Concrete and Materials Technology IncSackvilleCanada

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