Influence of the nature and amount of carbonate additions on the thermal behaviour of geopolymers: A model for prediction of shrinkage

In order to develop fire resistant geopolymer materials, it is necessary understand the parameters controlling their thermal behavior such as content of alkali or rare earth cations. This study highlights effect carbonate nature and amount on geopolymers in propose a model behaviour predict shrinkage. For this, various mixtures kaolin calcite and/or dolomite with different percentages were calcined at 600 750 °C. The feasibility consolidated materials based these evaluated obtained was investigated. characterization revealed persistence carbonates after calcination °C partial decomposition fact explained case high by existence kaolinite gangue hindering its decomposition. Consolidated from mixtures. After treatment 1000 °C, evidenced that amorphous phase crystallizes form major part leucite. At lower available alkaline species (Ca2+ Mg2+) content, only wollastonite formed shrinkage varies between 15 12%. However, higher calcium magnesium silicates can be calico-olivine larnite akermanite merwinite for materials. leads value (from 6 8%). Thus, possible control