Influence of calcium addition on calcined brick clay based geopolymers: A thermal and FTIR spectroscopy study

This study focused on understanding the behavior of brick clay containing a low calcium amount in an alkaline silicate solution. Silicate solutions were used and calcium (in calcite mineral form) was added during the brick clay preparation. The addition of calcium induces (i) a delay in the oligomer formation, (ii) a modification of the polycondensation reaction and (iii) an increase of the mechanical properties of the geopolymers. The addition of Ca in the brick clay materials increases the mechanical properties and this work highlights the role played by Ca cation in the structural modification of the consolidated materials.