Critical roles of synthetic zeolite on the properties of ultra-low cement -bonded Al2O3-SiC-C castables

Calcium aluminate cement-bonded Al2O3-SiC-C castables are widely used in practice due to sufficient initial strength and operability. However, a high amount of cement leads to deteriorated high-temperature properties due to the formation of low-melting-point phases. The present work aimed at optimizing the comprehensive properties of the ultra-low cement-bonded Al2O3-SiC-C castables with the introduction of high purity synthetic zeolite. The influences of additives on the properties of castables and the hydration behavior of cement were investigated. The results showed that zeolite had the following advantages: it promoted the hydration of cement through enhancing the physical absorption and potential chemical complexation of Ca2+ and eventually induced growth of the predominant plate-like hydrates (C(2)AH(8)) at 25 celcius. The formation of more C(2)AH(8) was beneficial to improve the green strength even with less cement. The substitution of cement with 0.5 wt.% synthetic zeolite contributed to improved high-temperature properties by reducing CaO content.