Different decomposition temperatures have been given for clays by different research workers. They are not easy to determine accurately because the rate of heating has pronounced effect. After the release of water from clay, it becomes a residual solid. The solid particles are closer together after the exodus of water which causes an overall shrinkage. The clay substance, on decomposition breakdown into the free oxides like Al203, Sio2 and H2O. The alumina in calcined kaolin behaves in exactly the same way as the corresponding amount of free alumina.
All kaolinitic clays after giving up their water, break down in to an anhydrides metakaolin which is labile, reactive, amorphous, quasi compound with the formula Al2o3, 2Sio2.
To be contd……….
