CT analysis of core samples from fire-damaged concrete structures

Fire can cause damage in structures. The level of damage depends on several factors, such as maximal temperature, duration of fire, constituents of the concrete and so on. It is necessary to design fire-resistant buildings and deal with possible reconstruction after fire. For the reconstruction, it is important to determine the level of damage and the necessary steps to take following the fire. This study investigates the possibilities and limitations of non-destructive test methods for fire-affected concrete structures by computed tomography (CT). For demonstration of the applicability of CT measurements, two cases are presented: (a) a 2 h fire test of a tunnel element and (b) a 1:1 scale fire test of a reinforced concrete building. CT analyses were carried out on samples. Considerable reduction of porosity was observed towards the concrete surface that was subjected to fire. The results of CT analyses agree well with the human observations of changing colours from gray to pink.