Possible new method for the assessment of fire–damaged concrete

Abstract

Five cylindrical flint aggregate concrete specimens from existing structures were subjected to temperatures in excess of 800°C for two hours. The use of speccally designed laboratory equipment allowed the determination of the final stabilized temperature profile in each specimen. After exposure, thin sections were taken longitudinally at the diameters of the specimens and examined petrographically. The method of thin section preparation allowed examination of the full range of concrete distress from the outer exposed surface inwards. Certain petrographic features were associated with particular zones of the final temperature profile which may be of use in establishing temperatures reached in concrete subjected to heat in uncontrolled conditions. A prime objective was the identfication of features that may be used to locate the structurally significant 300°C isotherm within damaged specimens.