Microstructure investigation, strength assessment, and thermal modelling of concrete exposed to different heating cooling regimes

Abstract Building fires are sometimes unavoidable due to unexpected accidents. During the fire, structural elements exposed temperatures above 1000 °C. Structural concrete loses its strength and stiffness during heating cooling cycle. In most cases, a real cooled by water quenching. It is rare scenario that, buildings subjected fire natural air without forced spraying. However, concrete’s residual (RS) in both cases after incident entirely different. Therefore, an experimental study was conducted understand heating–cooling (H–C) behaviour standard temperature. Concrete with different grades, namely C20, C30, C40, C50, considered present investigation. Specimens were higher following ISO 834 guidelines, then, temperature-exposed specimens either or spraying water. Investigations carried out evaluate fire-exposed hardened, micro-structural, thermal performance. The damage intensity of samples investigated observing crack pattern, width, porosity. Relationships between temperature exposure RS proposed predict fire-affected air- water-cooled specimens. Based on results, it found that water-sprayed exhibit loss (SL) than cool (AC). difference two regimes decreases increase durations. Damage level cracks for (WL) having grades.