Abstract
Geopolymer has good bonding structure of amorphous inorganic polymer which has excellent bonding agent properties and shows high bond strength in an early stage. Therefore, inorganic material like geopolymer which have advantages in previous research and has potential in replacing the organic materials in coating application. The chemical composition of the geopolymer materials which were metakaolin, ground granulate blast slag (GGBS) and fly ash contain mostly Silica (Si) and Aluminium (Al) which were possible source material for the manufacture of geopolymer coating. Based on Si:Al ratio and water:cement ratio were the important factor in the process of geopolymer coating which Si:Al of 3.5 and water:cement ratio of 0.25 gave the best result in strength in geopolymer coating. The common techniques for coating method that have been used were brush, spraying and dipping. From previous research, coating method influenced the greater result in fire proofing materials and high temperature. For compositions with Si:Al = 2.5 the adhesive strength was > 3.5 MPa while for Si:Al=1 and 2 only weak adhesion to the metal substrates was achieved in metakaolin based geopolymer coating. Fly ash geopolymer coating has improved the compressive strength of the coatings materials as high as 40 MPa with the high sintering temperature, 1500°C. Thermal expansion measurements in metakaolin geopolymer coating of the Si:Al = 2.5 composition revealed expansion of up to 6% at 800 °C, while for Si:Al = 1 and Si:Al = 2 compositions up to 4% shrinkage was observed. Keywords: Alkali Activated Binder, coating, geopolymer, XRF, XRD, SEM