Characterization of the Fracture Toughness of the Concrete Mortars Exposed to Elevated Temperatures

The main objective of this research was the characterisation of the fracture toughness of concrete mortars exposed to high temperatures by using notched specimens in three point bending tests. The specimens have different lengths and were heated at different temperatures ranging from room temperature up to 900°C. The experimental test results obtained are closed with those reported by the literature, it shows that beyond approximately 300°C, the fracture loads decrease strongly with the rise in heating temperature. However, between the room temperature (25°C) and 300°C, we recorded an increase of the fracture load. Two methods using the experimental critical load were applied to calculate the fracture toughness of concrete mortars: an analytical method based on the mechanics of continuous medium theory and a numerical approach using finite elements method. The numerical modelling has then been validated, discussed and compared with analytical solution. Comparison between the experimental results and the theory predictions was quite good.