Addition of dolomite into metakaolin as geopolymer: A preliminary study

Abstract

Metakaolin is one of the mainly used materials in geopolymer due to the aluminosilicate content in it. Besides that, dolomite is also materials that have aluminosilicate content which are lower than metakaolin. Because of that, the properties of metakaolin/dolomite geopolymer were studied. The parameters used for this study are solid to liquid of 0.6, alkaline activator ratio of 2.0 and sodium hydroxide of 10M based on previous studies. The metakaolin/dolomite geopolymer were prepared by mixing the solid precursor and alkaline activator using the mechanical mixer for 5 minutes and then casted in 50×50×50cm mold. The additions of dolomite into metakaolin were done by 10%, 20% and 30% by mass. The metakaolin geopolymer with no addition of dolomite act as the control for this study. The results for 7 days show that the minor addition of dolomite into metakaolin which is 10% gave better properties with 37.36MPa compared to others. The strength was supported by the morphology analysis by scanning electron microscopy (SEM), water absorption and density test. Morphology analysis shows the surface of lower compressive strength tends to have more pores, cracks, and unreacted materials. Other than that, increment of dolomite addition will only causes decrement of strength that is lower than the control for the geopolymer.