Physicomechanical Properties and Characterization of Gold Ore Tailings and the Utilization in Manufacturing of Geopolymer Concrete with Class F Fly Ash and Recycled Coarse Aggregates

The mining industry generates a large amount of waste, particularly in the form of tailing dumps, which creates major environmental difficulties such as air pollution, water pollution, soil erosion, and acid mine drainage. Previous studies confirmed that the mine waste could be used in making building materials, such as bricks, tiles, concrete blocks, pavement blocks, and precast concrete elements. However, gold ore tailings (GOTs) are recognized as major mine residues in the mining industry. In this study, GOTs were utilized as partial replacement material (0%, 5%, 10%, 15%, 20%, 25%, and 30% by weight) to fine aggregates such as river sand (RS) and low calcium fly ash (FA) as binder material in the manufacture of geopolymer concrete (GPC) along with recycled coarse aggregates. The GPC samples were cast and cured at room temperature until the curing ages; subsequently, the compressive strength of the samples was determined. This study demonstrated that the RS can be partially substituted in the manufacture of GPC by GOTs up to 15% with a slump value of 38.6 mm and the maximum compressive strength of 35.8 MPa. The mineralogical and chemical composition of raw materials (i.e., GOTs and FA) was analyzed using X-ray diffraction (XRD) and X-ray fluorescence (XRF), respectively. The XRD analysis revealed that the quartz has the highest peak intensity of 55% in GOTs and 50% of corundum in FA. The XRF analysis exhibited that GOTs and FA have high silicon oxides up to 39% and 38%, respectively. The crushed GPC samples were analyzed using field emission scanning electron microscopy to observe the morphological changes. The GPC sample comprised 15% GOTs exhibited denser and compacted microstructures.