Abstract Microstructure, texture, and mechanical and fracture characterization of three insulating commercial refractories were carried out in order to establish a correlation between these properties. The materials were characterized using X-ray powder diffraction (XRD) with Rietveld and Le Bail approximation to perform phase quantification, mercury intrusion porosimetry, and scanning electron microscopy. The mechanical behavior of insulating commercial refractories was studied with a multi-technique approach that involved a three-point bending test, uniaxial compression test, and single-edge notched beam (SENB) test. Stable fracture tests were successfully performed. The obtained results showed that the main differences between the materials studied were pore size distribution and mineralogical composition. Materials with the major amount of mullite had the highest values of the mechanical parameters in the different performed tests. Microstructure texture properties Xray X ray XRD (XRD quantification porosimetry microscopy multitechnique multi technique threepoint point test singleedge single edge SENB (SENB composition

Abstract Ceramic macro-needles incorporation as reinforcement in commercial refractory castable was studied. Ceramic macro-needles (Ø2x20 mm) were made from kaolinite clay and gibbsite to obtain mullite as the main crystalline phase. Specimens with the ceramic reinforcement were evaluated by compression after being treated at two temperatures (815 and 1400 °C). The results were compared with those obtained using the same commercial concrete but reinforced with steel fibers and without reinforcement. Compression values presented by specimens with ceramic macro-needles were 74% and 50% higher than specimens with steel fibers after exposition to 815 and 1400 °C, respectively. Based on these results, it was established that ceramic macro-needles are a feasible solution to improve the mechanical resistance of castables exposed to high temperatures.