The Effect of High Temperature on Compressive and Flexural Strength of Concretes Containing Glass Fiber

It is assumed that concrete structures are resistant to fire. Past research in this field has shown that in these structures, numerous problems occur during a fire. During the fire in concrete structures, fire fighters mainly use water to put out the fire. Upon contact with water, a great thermal difference occurs in the heated organ which affects most properties. No independent experimental study, to the researcher’s knowledge, has been conducted in order to investigate the effect of increased duration of high temperature on compressive and tensile strength of concrete containing glass fiber exposed to fire. However, the present study aims to investigate the effect of increased duration of high temperature on compressive and tensile strength of concrete containing glass fiber at a rate of 1%, 2%, and 3% exposed to high temperature (600 °C) in three different target times including 30 minutes, one hour, and two hours. Samples were cooled in two ways: slow cooling (exposure to air) and fast cooling (water spray immediately after exposure to heat). A total of 84 cubic samples (size: 150×150×150 mm and cylindrical samples sized 150×300 mm were prepared for studying compressive strength and tensile strength, respectively. After 28 days of processing and gaining the required strength, samples were put in annealing furnace and the experiments were conducted. The results showed that heat reduces the strength considerably. The slowly-cooled samples showed better performance compared to those cooled quickly. Also, heat caused many cracks in concrete samples.