Influence of Thermal Deformations and Pressure of Steam-Air Environment on Strength of Autoclave -Hardened Concrete

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Title: Influence of Thermal Deformations and Pressure of Steam-Air Environment on Strength of Autoclave -Hardened Concrete

Author(s): Sergey A. Mironov, Liarisa A. Malinina and Svetlana Cheryachukina

Publication: Special Publication

Volume: 32

Issue:

Appears on pages(s): 35-50

Keywords: air entrainmnet; autoclaving; compressive strength; concretes; corrosion; curing; damage; deformation; heating; hydration; lightweight aggregate concretes; microstructure; mortars (material); pressure; research; temperature rise; thermal expansion.

Date: 7/1/1972

Abstract:
The disruptive expansion of concrete which is experienced with either early or rapid application of heat in the autoclave is caused almost entirely by the expansion of the air and water vapor enclosed within the concrete. Deformations in concretre speciments caused by this gaseous expansion during autoclaivng have ben measured. It has been found that if external steamair environment presure is applied properly, these deformations can be prevented. Te method used is to seal the autoclave immediately after introduction specimens, and not vent the air during steaming. The result is that the pressure buildup inside the specimen is actually offset by the couter-pressure of the environment. Higher strenghs were obtained on 10-cm cubes cured in this manner thatn those cured in the usal way. An additional benefit of the method is aht mositure is "locked into" the specimen. Apparently the lack of air migration toward the exteriro helps retain moisture, as indicated by the lower moisture loss meaused when curing with steam-and-using a pressure of 1 atmosphere of air show that pressure reduces moisture loss and increases strength.