The influence of alumina content on the chemical and mechanical behavior of refractory concretes fired at different temperatures

Abstract The influence of different temperatures on the chemical and mechanical behavior of three types of refractory concretes is studied. These materials were formulated using cements and alumina aggregates of different qualities. The alumina content considered is 51, 71 and 90 wt.%. The methodology implemented included: X-ray diffraction (XRD), thermogravimetric analysis (TGA), digital scanning calorimetry (DSC) and compression tests. After 7 days of curing, specimens were exposed to room temperature, 150, 300, 600, 1000 and 1200 °C and tested. The comparative analysis of the stress strain curves showed a quasi-brittle behavior, linear at the beginning and then non-linear until fracture. The concretes exhibited differences in the mechanical behavior and properties in function of the content of Al 2 O 3 and CaO. For all refractories, a mechanical strength drop was observed as the temperature increased and at 1200 °C a recovery in the mechanical strength was noticed. The refractory with 51 wt.% of alumina showed an improved mechanical behavior for all temperature ranges when compared with to the others. The specimens with 90 wt.% of alumina had the least degraded mechanical behavior with the increase in temperature. The results indicate that different refractories with different mechanical properties can be used together as a lining material and applied in layers.