Development of Green Geopolymer Binders Utilizing Blended Ladle Furnace Slag (LFS) with Metakaolin (MK)

Geopolymer is defined as the chains of network of mineral molecules synthesized by a reaction of aluminosilicate mineral with alkali activator solution. It possesses good chemical and mechanical properties and has a great potential to be used in various application. The major aim of this research is to conduct a study on the geopolymer reaction utilizing blended ladle furnace slag (LFS) with metakaolin (MK) as a geopolymer precursor and the characterization of all the raw materials. The research focused on the relationship between of a series of samples with varying compositional ratios that was synthesized from a combination of LFS and MK. Setting time of fresh paste and compressive strength of hardened paste were determined using vicat needle test and compression machine respectively. For hardened paste, the mixes were cast in 50mm x 50mm x 50mm molds and the samples were cured in 60.C in the oven. The samples were examined after 7, 14 and 28 days in terms of porosity test, compressive strength test and degree of reaction. The characterization of chemical, mineralogical, physical characteristic, surface morphology and structural analysis of the particles was conducted by using various equipment such as XRF, FESEM, FTIR, XRD and Malvern Particle Size Analyzer. The results showed that LFS cannot be used on its own for geopolymerization process due to low content of Si/Al ratio. Higher loading of LFS causes higher porosity and reduces compressive strength. Therefore, the addition of MK was found to be necessary in order to improve compressive strength until the optimum level. The compressive strength however reduces after this point. It was observed that the best composition for binder was produced at a ratio of 50:50 ratio of LFS and MK (G-50:50).This formulation provided a consistent high compressive strength and slower setting time as well as the highest degree of reaction for a more convenient period of workability for application in construction or buildings.