Study of the Effect of Replacing Microsilica in Heat-Resistant Concrete with Additive based on Metakaolin

A comparative study is provided for the effect of microsilica additive and one based on metakaolin on hydration of alumina cement and cement stone structure formation after hardening and firing. It is established that in a composite with alumina cement an additive based on metakaolin promotes transfer of cement minerals into solution more rapidly than microsilica additive, and also that composite hydration with additive based on metakaolin proceeds more rapidly than a composite with microsilica. Additive based on metakaolin compared with microsilica improves mechanical properties of heat-resistant concrete based on a chamotte filler: after hardening and firing the ultimate strength in compression for specimens with additive based on metakaolin is higher by 5 – 27% than this index for specimens with microsilica additive.