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

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 degrees 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 degrees C because the morphology and structure of the dehydrated C(3)AH(6) and AH(3) remain similar. At 1000 degrees 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 alpha-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.