Preliminary assessment of utilizing Electric Arc Furnace (eaf) steel slag waste into geopolymer ceramic

EAF slag which generates vigorous fluxing action (due to high iron oxide content from 25.00 to 42.40 wt. %) when high firing temperature (1150 to 1180 °C) are applied in firing ceramic causing difficulties to control and leading to physical defects (warpage and blistering) on ceramic product. Hence, geopolymerization process is seen to replace the conventional firing process where alkaline activation is used which involving Na+ or K+ of functional groups, curing time and temperature to produce EAF slag-based geopolymer ceramic. Therefore, the objectives of this study are to evaluate suitability of EAF slag as raw material for geopolymer ceramic and to study the effects of curing temperature, curing time and alkaline medium to physical, chemical and mechanical properties of EAF slag-based geopolymer ceramic. The raw materials used which are EAF slag (obtained from one of the steel manufacturer in Malaysia) and China clay is characterized with X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF) and Fourier Transfer Infrared Spectroscopy (FTIR) to identify its composition, phases present and functional groups, respectively. The EAF slag is crushed and ground before mixing with the sodium hydroxide (NaOH) solution (after diluted with distilled water to 2 M) where ratio used is 8:92. The paste formed then is moulded and undergo pre-curing at 25 °C for 24 h followed with different post-curing temperature (25 °C, 60 °C and 80 °C) for 24 h. The final products are characterized in terms of water absorption, apparent porosity, bulk density, phase analysis and microstructure analysis via optical microscope (OM). Results shows that utilization of EAF slag into geopolymer ceramic increases its percentage of water absorption, apparent porosity, bulk density and compressive strength supported with microstructure of end products formed. Thus, EAF slag is suitable to be utilized in geopolymer ceramic.