ABSTRACT
Concrete, during exposure to elevated temperatures, is characterized by low thermal diffusivity and incombustibility, resulting a satisfactory performance against fire. However, chemical and physical changes occur in its components. The stability of the compound relates to its microstructure, so it is possible to verify the material degradation using advanced techniques of microstructural analyses. In this context, the use of materials tests, such as diffraction and fluorescence X-ray, proves attractive. In this paper, it is described the pre-fabricated cellular slab inspection, an industrial building, which has undergone exposure to high temperatures emanating from a fire in the building ground. It was evaluated the structural element by chemical characterization tests with different thickness of the concrete slab, estimating the temperature reached in each layer and, consequently, the resistance loss of the structural element. From the results, it was found the temperature of approximately 700 ºC in the slab surface and less than 100 °C in the deeper layers. It was estimated the reduction in strength of concrete in the order of 25 % in 20 mm layer and negligible reduction in the region of prestressed wire, attesting to the structural safety of the structure after the accident.
Keywords:
Concrete; High temperatures; Residual resistance; X-ray diffraction; Fluorescence x-ray
