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Chemistry of AAC

All in all, the combination of cement, lime, gypsum (anhydrite), finely ground sand or Pulverised Fly ash and most importantly aluminium powder causes the mixture to expand considerably. 
 
From the beginning to the end the simplified chemical reactions look as follows: 

1. CaO+H2O Ca(OH)2 + 65,2 KJ/mol
2. 3Ca(OH)2 + 2Al + 6H2O Ca3(Al(OH)6)2 + 3H2
3. 6SiO2 + 5Ca(OH)2 5CaO · 6SiO2 · 5H2O 

This is what the final Tobermorite or Hydrated Calcium Silicate C5S6H5.


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