Processing and characterization of calcined kaolin cement powder

This paper aimed at investigating the possibility of calcined kaolin to produce cement powder that could be an alternative to Portland cement by applying geopolymerization process. Cement paste was firstly made by alkaline activation of calcined kaolin with alkali activator (mixture of 6–10 M NaOH and Na2SiO3 solution), heated in oven at temperature of 80 °C forming a solidified product, followed by pulverization to fixed particle size powder. The parameters involved in this processing route (alkali concentration, calcined kaolin to activator ratio, alkali activator ratio and heating conditions) were investigated. For compressive testing, cement powder was added with water and then cured to produce cubes. Compressive strength, microstructure, XRD and FTIR analysis were studied. Result showed that the processing route has the potential to produce cement powder where SEM micrographs have proved that the geopolymerization process continued after addition of water forming a homogeneous structure and geopolymers bonding increased in intensity which was observed through IR analysis. It was believed that presences of crystalline phase as seen in XRD diffractogram were good for mechanical properties.

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► Processing route producing cement powder alternative to current cement was developed.
► NaOH concentration, activator ratio and heating conditions affect strength markedly.
► Water plays important role in geopolymerization process.
► Geopolymerization continued after addition of water forming homogeneous structure.
► Presences of crystalline phase are favorable to compressive strength.