Impact of nano addtives on the performance of low cement refractory castable

Abstract

The use of nano additives has attracted great interest due to the impact on the hydration of calcium aluminate cement (CAC) and possibilities to change the properties of refractories. In this work, the properties of low cement castable (LCC) with 0; 0.3; 0.5 and 0.8% of nano-silica (NS) and combined superplasticizer (0.2%) with the CAC content of 7.0 wt% were investigated. The physical, mechanical, and thermal properties of the castables after thermal treatment (105, 800, 950, 1100 and 1200°C) were determined. The SEM results obtained show a positive effect of NS on the formation of the structure during its hardening. Modification of the binder with nano-additives results in a more densified structure, as a result, a lower total porosity and a higher amount of the smallest pores in the microstructure formation of the LCC. NS was found to increase density, cold crushing strength and thermal shock resistance of LCC; reduces shrinkage, and the optimal NS content was found to be 0.5 wt%.