Use of X-ray CT for analysis of concretes exposed to high temperatures

conference paper

English

Concrete has many advantageous properties, e.g. inflammability or low temperature conductivity. However, when a concrete construction is exposed to high temperatures, it loses its load-bearing capacity, especially in surface layers which are loaded at most. A serious problem represents the so-called explosive spalling which is caused by the combination of increasing pressure in inner pores and inner compressive stresses originating from material expansion at higher temperatures. Spalling of a concrete layer leads to weakening of the concrete cross section of a reinforced construction and, in some cases, to exposure of steel reinforcement to temperatures above the critical level. Defects can be so serious that the complete construction gets destroyed. Design of a concrete mixture with resistance to thermal exposure for a certain period of time has been classified among the passive fire protection methods. Basic composition of the cement concrete can be problematic, as it is the composite material consisting of two markedly different components, i.e. the cement paste and aggregate. When exposed to high temperatures, both components behave differently and their physical, chemical and mechanical properties change (for example Mindeguia, J.C., 2013)

X-ray tomography, concrete, cement paste, aggregate, high temperature

BODNÁROVÁ, L.; SITEK, L.; SOUČEK, K.; STAŠ, L.

2014

25. 6. 2014

Ostrava

978-80-86407-49-4

GECO 2014

5

87

88

2