Faculty Publications
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Item 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(American Society of Civil Engineers (ASCE), 2023) Lokesha, E.B.; Mangalpady, M.; Kumar Reddy, S.K.; Srinivasa, A.S.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. © 2023 American Society of Civil Engineers.Item Development of Regression Model and Optimization of Mechanical Properties of Geopolymer Concrete Prepared Using Gold Ore Tailings(American Society of Civil Engineers (ASCE), 2023) Lokesha, E.B.; Mangalpady, M.; Kumar Reddy, S.K.; Srinivasa, A.S.In this study, 11 mix proportions of geopolymer concrete (GPC) beam and cylinder samples were prepared by partially replacing the class F fly ash (FA) as the binder with ground granulated blast furnace slag (GGBFS) in steps from 10% to 100%, along with gold ore tailings (GOTs) [as a partial substitute to the river sand (RS) in steps from 5% to 30%] and recycled coarse aggregates (RCAs). The laboratory tests demonstrated a maximum split tensile strength of 5.99 MPa and flexural strength of 7.98 MPa for Sample GOT-11-15 (11 indicates Mix Proportion-XI and 15 indicates 15% of GOTs) of Mix Proportion-XI. In addition to the previous 11 mix proportions, one more set of cylinders and beams was prepared using FA, GOTs, and natural coarse aggregates (NCAs), which are designated as Mix Proportion-XII. For Mix Proportion-XII, the highest split tensile strength of 4.17 MPa and flexural strength of 6.13 MPa was achieved for Sample GOT-15 (15 indicates 15% of GOTs). Among the 12 types of mix proportions, Sample GOT-0 of Mix Proportion-XII (i.e., FA 100%, GOT 0%, and NCAs 100%) showed a maximum slump value of 89.3 mm. Sample GOT-1-0 of Mix Proportion-I (i.e., FA 100%, GOT 0%, and RCA 100%) exhibited the maximum slump of 65.3 mm. The field emission scanning electron microscopy (FESEM) analysis indicated that silicon (Si) and aluminum (Al) were the two main constituents of the GOTs and FA. In addition, this analysis revealed the existence of uneven forms of quartz particles in GOTs and the spherical shapes of the FA particles that adhered to the RCAs. The multiple regression analysis exhibited the root mean square (R2) values of 89.0% and 85.5%, respectively, for the split tensile and flexural strengths. The p-value for the developed model was <0.05; therefore, the developed model was considered significant and the best-fit model. © 2023 American Society of Civil Engineers.Item Durability characteristics of geopolymer concrete produced using gold ore tailings along with recycled coarse aggregates(Nature Research, 2025) Lokesha, E.B.; Mangalpady, M.; Kumar Reddy, S.K.The Gold Ore Tailings (GOTs) are one of the major waste materials in the mining sector. The disposal of these tailings could be a problem for human health and a major environmental concern for several years. In this research work, the GOTs were used as an alternative material to the River Sand (RS) in the production of Geopolymer Concrete (GPC). Thus developed GPC samples were tested for its durability characteristics, such as resistance to sulphates and chlorides. The sulphate attack test was conducted by immersing the Conventional Concrete (CC) and GPC samples in 5% Magnesium Sulphate (MgSO4) solution for various curing periods. In this test, the GPC samples showed a reduction in compressive strength and weight, which is slightly more when compared to CC samples. The Rapid Chloride Penetration Test (RCPT) was also conducted to know the chloride ion penetration in which GPC samples exhibited less chloride penetration when compared to CC samples. Further, the Toxic Characteristic Leaching Procedure (TCLP) analysis showed that the GOTs have very high concentrations of hazardous metals. However, the concentration of Cyanide (CN?) was minimal in GOTs. In this regard, geopolymerization would be a better method for immobilizing the hazardous metals in GOTs. © The Author(s) 2025.