Preparation of CaCO3-Containing Geopolymers for Green Concrete

Geopolymers were prepared by using the dried fly ash from industrial by-product, NaOH as alkaline activator and Na2SiO3 as liquid glass. Calcium carbonate from a clam shell was added to provide attachment and growth of environmental organisms on the geopolymers. We investigated the effects of a shell powder contents on the microstructure and bonding properties of the geopolymers to normal cement. The major chemical compositions of fly ash were Si and Al at the ratio of 2 to 1 in wt%. The shell powder with layer sheet consisted of aragonite phase. As increasing the amount of the shell powder, fly ash was not polymerized and remained spherical. The bonding between geopolymers and normal cement was obtained when 0-15 wt% of the shell powder was added. On the other hand, bonding was not achieved with higher shell contents of 20-25 wt%.