High Temperature Effect on High Performance Concrete (70 - 600 C) strength and porosity

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Title: High Temperature Effect on High Performance Concrete (70 - 600 C) strength and porosity

Author(s): A. N. Noumowe, P. Clastres, G. Debicki, and M. Bolvin

Publication: Special Publication

Volume: 145

Issue:

Appears on pages(s): 157-172

Keywords: compressive strength; high-performance concretes; strength; high temperature; microstructure; porosity; spalling; Materials Research

Date: 5/1/1994

Abstract:
Investigates the effect of high temperatures (70 to 600 C) on the residual strength of ordinary and high-performance concretes made with the same cement and aggregates. Measurements of weight losses and residual strengths were carried out. Between 25 and 600 C, the mass loss was about 8 percent of the wet concrete weight. The tests showed that after being exposed to a temperature of 600 C and then cooled, the concrete retains 38 to 46 percent of its initial compressive strength. Experimental results indicated further that mercury porosimetry measurements were suitable for obtaining information about microstructural changes resulting from thermal exposure. The distribution function of the pore system indicated that no remarkable changes had taken place in its shape and location up to 120 C. The residual porosity increased with temperature, particularly after 300 C, and the pore size distribution was significantly modified. Approximately one-third of the high-strength concrete samples failed through explosion at about 300 C. With the results obtained, the authors were able to analyze the phenomenological aspects susceptible to explain the observed behavior. This behavior might be caused by a tension in the solid microstructure produced by thermal stresses and by the pore vapor pressure.