Utilization of Ferronickel Slag Waste and Fly Ash for Geopolymer Manufacture

• Main Author: Anisa Dwinidasari, Aya
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/38334
• Institution: Institut Teknologi Bandung

Indonesia’s focus on infrastructure improvements increases consumption rate of Portland cement as binder material. This raises environmental concerns because the industry is one of main contributor global CO2 emissions generated through calcination and combustion processes. Alternative environmentally friendly construction material is geopolymer. Geopolymers are inorganic polymers formed from an activation reaction between aluminosantic solids and concentrated alkaline solutions. Sources of aluminosilicates can be obtained from industrial waste, such as slag and fly ash. The high volume of waste in industrial smelters and PLTU is a huge potential for the utilization of this industrial waste as precursor for geopolymers. Therefore, a review of the feasibility of ferronickel slag and fly ash as precursor usage instead of Portland cement was carried out in this research. Variations of this research are composition of ferronickel slag and fly ash as precursor, ferronickel slag size and curing time at 60oC according to the full-factorial design. The step of this research began with the preparation of raw materials (precursor) consists of grinding ferronickel slag to various sizes and analysis of precursors. Production of geopolymers is carried out by mixing the precursors according to composition variation with activator solution and sand. The activator solution used is a mixture of NaOH and water glass with a fixed ratio of 2:1 and ratio of solid to liquid (S/L) used is 3.33. The mixture was then molded and cured 60oC at spesific curing time based on variaton. Further curing process was carried out at room temperature for each variation in seven days. Test applied on geopolymer was compressive strength, FTIR, XRD and SEM. The technical feasibility of geopolymers will be reviewed by comparing the results of compressive strength testing according to applicable concrete standards. Based on compressive strength, geopolymer with ferronickel slag precursors of size -325 mesh and coal fly ash with ferronickel slag composition of 20% and curing treatment for 48 hours has a proper compressive strength and in accordance with SNI 15-2049-2004 type IV and V, ASTM C270 types S, O, and K, and SNI S-04-1989-F types I, II, II, and IV with compressive strength of 7.08 MPa after seven days curing. This shows that geopolymers are suitable to be used as a substitute for Portland cement binders in concrete manufacturing FTIR, XRD and SEM tests applied on geopolymer samples show the characteristics of the geopolymerization reaction.