Effect of quartz sand on the properties and alkali resistance of refractory aluminosilicate castables

Abstract

This study investigated the effect of ground quartz sand (0, 2.5%, 5.0%, and 7.5%) on the alkali resistance, physical and mechanical properties, porosity, and thermal shock resistance of castables containing different amounts of calcium aluminate cement (conventional cement content, medium cement content, and low cement content). It was found that the addition of ground quartz sand (d50 was approximately 8 µm) increased the alkali resistance by a factor>5, decreased the total porosity, and increased the strength of the castable (up to 5%), irrespective of the amount of calcium aluminate cement in the composition. The analysis of the EDS results after the alkali attack tests shows that the thickness of the formed protective barrier, depending on the type of castable is 650–1100 µm. However, over 2.5% of ground quartz sand significantly (>20%) decreased the thermal shock resistance of concrete owing to the polymorphic transformation of quartz.