Compressive Creep of Fireclay Refractories With Varying Recycled Content

The compressive creep behavior of fireclay bricks containing different amounts of recycled fractions was examined. Uniaxial compressive creep tests were performed up to 1100°C and evaluated using the Norton–Bailey creep law. For equal loads, both creep strain and creep strain rates decrease with increasing recycled material content. At 1100°C, the low recycled material variant shows a higher initial creep before its slope declines, whereas the curves of the higher recycled material content variants remain steeper for longer times. Chemical and mineralogical analyses indicate very similar overall compositions. However, the microstructure of the low‐recycled material variant reveals a partial clay–mineral‐like morphology that is absent in the others. Recycled material fines introduce additional minerals, altering the overall fines composition. As a result, during the burning process, high‐recycled material matrices generate more liquid at a given temperature, which accelerates phase transformations, removes texture after firing, and lowers initial creep‐strain rates during creep testing. Microstructural observations after compressive creep test, together with increases in bulk density and Young's modulus, support this interpretation. For the investigated case, increasing the recycled material content does not seem to compromise and might improve compressive creep resistance during the primary creep stage, indicating potential for sustainable reuse.