The characteristic of andesite waste powder (AWP) as a replacement for fly ash geopolymer paste

Abstract Large-scale production of andesite has created much waste. Andesite waste material has SiO 2 (Si) as a main component and causes pozzolanic activity. During the mining, processing, and polishing steps, almost 70% of this waste is thrown away. This research studied the potential of andesite waste material (AWP) as a substitution for fly ash. Six compositions of geopolymer paste with AWP were mixed to determine the ability of andesite waste powder (AWP) to be a silica source material in geopolymer paste. AWP ranged from 0%, 10%,20%,30%,40% and 50% from the unit weight of fly ash. 10 Molar of NaOH and Na 2 SiO 3 were used as an alkaline activator. The ratio between Na 2 SiO 3 and NaOH was constant at 2. The water-to-solid ratio was kept constant at 35%. Flow test and compressive strength of geopolymer were tested according to ASTM C1437 and ASTM C109, respectively. The result showed that the AWP affected the workability of the geopolymer paste. The geopolymer unit weight increases at 10% of AWP and decreases gradually when the AWP content rises. The geopolymer achieves a maximum compressive strength of 41.55 MPa over 28 days when 30% AWP is used. As a silica source, AWP can be used to replace fly ash geopolymer, based on the study’s results.