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The main intention of this research is to reuse the industrial by product ferrochrome slag and silica fume as a partial replacement of natural coarse aggregate and fly ash, respectively for the production of Geopolymer concrete with improved mechanical properties. Natural coarse aggregate was replaced by ferrochrome slag (FS) in varying percentages from 0 to 40% by weight. Fly ash was replaced by silica fume (SF) at different percentages 0 to 15% by weight. The combined effect of FS and SF was studied by developing Geopolymer concrete. Tests for compressive strength, splitting tensile strength and flexural strength of the GPC have been carried out at 7, 28 and 90 days of curing. The scanning electron microscope (SEM) was performed for the inspection of surface texture of the microstructure of the hardened samples. X-ray diffraction (XRD) was conducted to investigate the crystallinity of the mineral phases of the material as well as the activation product. Fourier transformed infrared spectroscopy (FTIR) was carried out to know the degree of polymerization of the samples. At 28 days, compressive strength, splitting tensile strength and flexural strength of GPC produced by replacing 30% FS and 10% SF increases by 38.9%, 47% and 20.4% respectively. Acronyms: CS Compressive strength; FS Ferrochrome slag; NCA Natural coarse aggregates; NFA Natural fine aggregates. [ABSTRACT FROM AUTHOR]

This study introduces the possible utilization of water cooled ferrochrome slag, an industrial waste from ferrochrome industry in concrete production. Traditional sand was substituted with six percentages (0% for reference mix, 10%, 20%, 30%, 40% and 50%) of ferrochrome slag by weight in all concrete mixtures. Leaching, micro-structural and mechanical properties, these three aspects were explored for the qualification of ferrochrome slag concrete. Different tests for the physical and mechanical performance of the concrete were done and the outcome demonstrated that substitution of sand by ferrochrome slag reduced a little in the performance of the strength and water absorption increases along with the increase of rate of substitution. However, the concrete having 30% ferrochrome slag shows almost comparable results with the reference mix. Leachability characteristics were also observed by pH dependence leaching test method for the five concrete samples and one raw slag sample. Moreover, micro-structural study of reference mix and concrete mix with 10–50% ferrochrome slag was performed by utilizing SEM techniques. This experimental study concludes that that ferrochrome slag can be used in the production of concrete as a partial substitution of traditional sand with no unfavourable ecological, micro-structural and mechanical effects. Cr- Chromium; FeCr- Ferrochrome; GBFS- Granulated Blast Furnace Slag; ISF- Imperial Smelting Furnace; PSC- Portland Slag Cement; SAI- Slag Activity Index; SEM- Scanning Electron Microscope; TCLP- Toxicity Characteristic Leaching Procedure; USEPA- United States Environmental Protection Agency; WCFS- Water Cooled Ferrochrome Slag; XRD- X-Ray Diffraction [ABSTRACT FROM AUTHOR]