Effect of silicon carbide aggregate, prepared by different methods, on the properties of refractory concrete with cenospheres

Abstract

This paper presents the effect of different preparation methods (milling by ball mill or collision milling by disintegrator) of silicon carbide aggregate (SiCA) on the properties of refractory concrete with cenospheres (CNPs). The different milling methods are known to have a significant effect on the morphology of aggregates, their shape, and specific surface area. SiCA prepared by different methods and CNPs influence the hydration course of aluminate cement (AC) paste. Disintegrated SiCA prolongs the process of AC hydration more noticeably (by 1.25 h) compared to milled SiCA. CNPs prolong this process by 1.5 h. Disintegrated SiCA in the amounts of 5–15% was found to improve the mechanical properties of refractory concrete after hardening by 5.5–16.6%, 12.5–30%, and 9–57% after firing at temperatures of 1000°C and 1200°С, as compared to the same amount of milled SiCA in the mix. Disintegrated SiCA in the same amounts was found to increase the firing shrinkage of refractory concrete by 16–31% and by 0.33–0.35% after firing at 1000°C and 1200°С, as compared to the same amount of milled SiCA in the mix. The addition of 5–15% of CNPs into refractory concrete mixes containing 15% of disintegrated SiCA, after firing at 1200°С, results in a decrease in density (from 2080 to 1490 kg/m3), firing shrinkage (from 0.35% to 0.18%), and strength (from 22 to 16 MPa) of the samples.