EXPERIMENTAL INVESTIGATION AND NON-LOCAL MODELLING OF THE THERMOMECHANICAL BEHAVIOUR OF REFRACTORY CONCRETE

This paper describes an experimental characterisation and a non-local finite element analysis on the influence of the testing temperature on the mechanical properties and cracking propagation in refractory cement bricks. Therefore, isothermal four-point bending and uniaxial compression tests have been carried out at different testing temperatures (25, 500, 800, and 1000 degrees C) to determine the stress-strain response for each independent testing temperature. Based on this response, material constants are identified using the inverse estimation method. Then, they are introduced in a non-local finite element model using CAST3M software. The experimental results indicate that with an increase in the testing temperature, the thermomechanical behaviour of the refractory concrete shows a critical temperature of 800 degrees C, for which the compression and tensile strengths are the largest. Their values are respectively around 28 and 9 MPa. The present numerical simulation results indicate two types of crack propagation; continuous crack failures when the temperature varies between 25 and 800 degrees C and multi-identified cracks producing a localised damage zone at 1000 degrees C. Notably, the sample tested at 1000 degrees C requires a deflection of 0.2 mm to achieve 0.3 (30 % damaged). In contrast, the damage variable achieves 1.0 (100 % in damage) for the sample tested at 25 degrees C with the same imposed displacement (0.2 mm). Finally, the enhanced non-local damage model produces a realistic simulation of the experimental failure mechanisms, proving the validity of the implementation method.