Metakaolin as an effective additive in the production of AAC

The paper presents a study of the current state of autoclaved aerated concrete production. Global trends of autoclaved aerated concrete market confirm the tendency to reduce the density of wall blocks from 400–500 kg/m³ to 300–350 kg/m³. At the same time their strength level is required to be maintained. The search for inexpensive and available local effective pozzolanic additives may increase the economic and ecological attractiveness of AAC production.

The performed studies have shown that using metakaolin additive helps to reduce energy consumption for AAC production. As a result of the research it was found that metakaolin can act as an alternative component of binder in aerated concrete mixture and replace gypsum additive. Metakaolin in the low density aerated concrete mixture stabilizes the processes of macrostructure formation of raw AAC. Performing functions of gypsum stone, this additive has a positive effect on the strength of the aerated concrete.

Industrial tests have shown that the efficiency of metakaolin additive increases as the density of the aerated concrete decreases. The greatest effect of use of additive metakaolin is noted in concrete mixtures of low density (130‐150 kg/m³). It is advisable to introduce the additive into the aerated concrete mixture together with other components at the stage of mixture formation.