Impact of metakaolin additive on residual mechanical properties of cement based composites loaded by high temperature

Abstract

The aim of this paper is to describe the influence of the composition of refractory composites on their response to gradual thermal loading. Aluminous cement binder system was modified by metakaolin additive which is produced by calcination and grinding of natural clay. Studied aluminous additive is often used for production of high strength composites with increased mechanical and durability properties. The fundamental problem of these composites is their brittle rupture which is why studied composites were reinforced by very short ceramic fibers.Studied aluminate binder system in combination with natural basalt fine aggregates ensures sufficient resistance to high temperature exposure. The influence of composition changes was evaluated by the results of physical and mechanical testing -compressive and flexural strength and bulk density were determined on the different levels of temperature loading. Application of ceramic fibers brought an expected linear increase of mechanical parameters of studied composites just up to dose of 4% by volume. Metakaolin replacement showed the optimal dose just about 20% of aluminous cement weight.The extensive application of cement supplementary materials has an important motivation because of high energy consumption of aluminous cement based refractory composites. It was experimentally verified that the appropriate combination of aluminous cement with metakaolin additive and natural crushed basalt aggregates ensure sufficient properties for practical utilization of proposed composites.