The effect of elevated temperature on the mechanical properties of concrete produced with raw perlite aggregate

Deterioration caused by elevated temperatures in the micro and of concrete can lead to serious decreases in the mechanical properties of the material. In this context, it is important to determine the mechanical properties of the materials constituting the structure to assess the current condition of the reinforced concrete structure after the fire. The present experimental study investigates the effects of elevated temperatures (25 °C, 200 °C, 400 °C, and 600 °C) on cubic and prism samples fabricated with two different aggregate types (raw perlite aggregate and traditional coarse aggregate) by considering four different concrete mixtures (C25, C40, P25, and P40). Additionally, the aim is to reveal the usability of a raw perlite aggregate as an alternative to traditional concrete production in facilities that are likely to be exposed to elevated temperature effects. In line with these aims and objectives, experiments and visual observations were conducted before and after exposure to elevated temperatures using both destructive (e.g., compression test and bending test) and non-destructive (e.g., mass loss, UPV, SEM, color, and crack deterioration) methods. The results show that although they initially have similar mechanical properties (e.g., compressive strength), the deterioration in the P25 and P40 samples is more limited with increasing temperature compared to the C25 and C40 samples. Additionally, although the bending strength of the P25 and P40 samples at 25 °C is lower than that of the C25 and C40 samples due to the more limited stress-strain relationship of the perlite samples, it is observed that the specimens with the same compressive strength show similar flexural behavior under the effect of increasing temperature.