Effect of CAC content on the strength of castables at temperatures between 300 and 1000 °C

Abstract This study investigates the strength progression of calcium aluminate cement (CAC)-bonded castables with a CAC content ranging from 2 to 16 wt% in the temperatures between 300 and 1000 °C. Focusing on the phase changes and microstructure evolution of the hydrates due to heating, we discovered that castables with higher CAC contents have increased strengths between 300 and 800 °C because the morphology and structure of the dehydrated C3AH6 and AH3 remain similar. At 1000 °C, a higher strength of the 16 wt% CAC castable results from the higher degree of coalescence/sintering between the particles formed from the decomposition products of CAC hydrates. The CAC-bonded castables were prepared using tabular alumina aggregates and α-Al2O3 micro-powder as starting materials, and CAC as the binder. The phase compositions and the microstructures of the castable matrices were characterised by X-ray powder diffraction and scanning electron microscopy, respectively.