Evaluation of compressive strength in geopolymer mortars produced using iron ore tailings ground by tumbling ball mills

Abstract

The use of Iron Ore Tailings (IOT) as finer aggregates and/or fillers in geopolymer mortars is a possible alternative to use the high amount of solid mining wastes produced nowadays. In this study, exploratory tests were carried out to evaluate different proportions of materials that could produce a geopolymer mortar with high compressive strength. The higher compressive strength was obtained considering 50% of IOT, 25% of commercial metakaolin and 25% of an alkaline solution with 1:3 ratio of commercial sodium hydroxide solution (NaOH) and commercial sodium silicate solution (Na 2 SiO 3 ). The compressive strength obtained after 3 days of curing in room temperature was 23.5 MPa. Then an experiment was carried out to evaluate a possible increase in compressive strength promoted by grinding IOT. The IOT were ground for 1, 2 and 3 hours using a tumbling ball mill and the finer IOT were used to produce geopolymer mortars considering the same proportions of materials which higher compressive strength was obtained without grinding IOT. The grinding process for the IOT investigated showed to be not effective, as it gives similar compressive strength results as without grinding.