- Author
-
Snyder, K. A.
- Title
- Suspended Hydration and Loss of Freezable Water in Cement Pastes Exposed to 90% Relative Humidity.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Journal
-
Cement and Concrete Research,
Vol. 34,
No. 11,
2045-2056,
November 2004
- Keywords
-
cement pastes
|
hydration
|
water
|
humidity
|
calorimetry
|
curing
|
microstructure
- Identifiers
- degree of hydration (nominated)
- Abstract
- Degree of hydration (DOH) and differential scanning calorimetry (DSC) measurements are used to characterize the effect of early exposure to a 90% relative humidity (RH) environment on cement paste hydration. Early exposure to a 90% RH environment can lead to the consumption of freezable water and altered microstructural development. The minimum duration of 100% RHcuring required to eliminate the effects of an unsaturated environment on microstructural development coincides with the appearance of a DSC peak near -30 deg C that occurs in the range 1-14 days for the pastes studied. The Jennings colloidal microstructural model is used to argue that the -30 deg C peak coincides with the cessation of capillary pore percolation. Alternatively, all samples cured under 100% RH conditions for 7 days prior to 90% RH exposure hydrated at the same rate as those continuously exposed to 100% RH. The application of these results to the formulation of separate curing practices for durability and strength is discussed.