Development of sustainable concrete using iron ore tailings as sand replacement

The increasing demands for iron ore worldwide have resulted in the generation of billion tonnes of iron ore tailings (IOT) which were found in all the iron ore mining industries. Rapid increase in consumption of river sand due to the increased in construction activities over exploited the riverbeds. This has led to a range of problems which include: depletion of natural sand, increased riverbed depth, water table lowering, intrusion of salinity and destruction of river embankment. This study explored the possibility of using IOT as a replacement for natural river sand in concrete production. Laboratory investigations were conducted to evaluate the characterization of IOT materials in terms of microstructure, physical and chemical properties. Leaching behaviour of IOT materials was also determined. Furthermore, mix design and the evaluation of the fresh and hardened properties of the IOT concrete were executed. Series of concrete were prepared with IOT at a replacement level of 25%, 50%, 75% and 100%, using water to cement ratio (w/c) of 0.40 and 0.60. Fresh properties of mixtures in terms of concrete slumps and density were studied. The hardened properties examined are mechanical strengths, deformation characteristics, durability properties and corrosion measurement. Corrosion rate were evaluated using linear polarization techniques. Finally, microstructural tests in terms of X-ray Diffraction (XRD), Field emission scanning microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR) and Thermo gravimetric analysis (TGA) were concurrently conducted on control and IOT concrete in order to determine the interaction and effect of the IOT material that brings about the performance of the concrete. A correlation coefficient using fitted linear regression analysis was performed on compressive strength to evaluate the significant level of concretes containing IOT. Results showed that IOT affect mixture workability negatively. However, the inclusion of super plasticiser showed tremendous influence in increasing the workability and reduced this drawback. At 50% replacement, the compressive strength of the concrete at 28 days was 65.6 and 37.7 MPa for 0.40 and 0.60 w/c ratio, respectively, which shows an improvement of 9% and 12% over the concrete with river sand. Concrete with IOT indicates a good resistance to carbonation compared to control specimen. Linear polarization resistance (LPR) results indicates that, corrosion rates of 0.02 mm/year for IOT concretes were the same with control at 0.60 w/c ratio while 0.01 mm/year was observed for control at 0.40 w/c ratio. Considering all these test results, 50% river sand replacement with IOT resulted in concrete of excellent strength and adequate durability performance except for exposure to acid attack. However, it has the quality to be used as partial replacement of sand

Mechanical properties of self-compacting geopolymer concrete containing spent garnet as replacement for fine aggregate

Millions of tons of spent garnet, a by-product of surface treatment operations, are disposed of in landfills, oceans, rivers, and quarries, among others every year, thus it causes environmental problems. The main objective of this study is to evaluate spent garnet as a sand replacement in concrete prepared with ground granulated blast furnace slag (GGBS)-based self-compacting geopolymer concrete (SCGC). Concrete mixtures containing 0%, 25%, 50%, 75% and 100% spent garnet as a replacement for river sand were prepared with a constant Liquid/Binder (L/B) mass ratio equal to 0.4. Compressive, flexural and splitting tensile strengths as well as workability tests (slump, L-box, U-box and T50) were conducted on concrete containing spent garnet. As per specification and guidelines for self-compacting concrete (EFNARC) standard, the test results showed that the concrete’s workability increased with the increase of spent garnet, while all the other strength values were consistently lower than conventional concrete (SCGC) at all stages of replacement. The results recommended that spent garnet should be used in concrete as a sand replacement up to 25% to reduce environmental problems, costs and the depletion of natural resources

Influence of high temperature on strength and microstructure properties of concrete containing iron ore tailings

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Effect of sulphuric acid on concrete with iron ore tailings

Researches into the uses of waste materials are increasingly being explored to meet up society’s needs and global protection for sustainable, safe and economic development. This paper assessed concrete with iron ore tailings (IOT) exposed to dilute sulphuric acid. Iron ore tailings are the materials left-over after separating the valuable fraction from the uneconomic fraction of an ore. To study the effect of sulphuric acid, concrete of 100 mm cube with a different mix ratios containing IOT were prepared and cured for 28 days in water. The cubes were later immersed into dilute sulphuric acid at a concentration of 5%. The compressive strength of concrete at 7, 28 and 90 days of water curing were determined. Mass loss and strength reduction due to sulphuric effect were evaluated at 7, 28 and 90 days respectively. XRD microstructure of concrete specimens was analysed. Test results indicated that the IOT could be used in concrete as sand replacement since the concrete with IOT has similar trend in compressive strength loss and mass loss to sulphuric acid attack compared to control specimen. The mineralogical crystal failure patterns due to the sulphuric acid in terms X-ray diffraction analysis are the same for control and IOT concrete

Strength and Microstructure of Concrete with Iron Ore Tailings as Replacement for River Sand

River Sand is one of the basic ingredients used in the production of concrete. Consequently, continuous consumption of sand in construction industry contributes significantly to depletion of natural resources. To achieve more sustainable construction materials, this paper reports the use of iron ore tailings (IOT) as replacement for river sand in concrete production. IOT is a waste product generated from the production of iron ore and disposed to land fill without any economic value. Concrete mixtures containing different amount of IOT were designed for grade C30 with water to cement ratio of 0.60. The percentage ratios of the river sand replacements by IOT were 25%, 50%, 75% and 100%. Concrete microstructure test namely, XRD and Field Emission Scanned Electron Microscopic/Energy dispersive X-ray Spectroscopy (FESEM/EDX) were conducted for control and IOT concretes in order to determine the interaction and performance of the concrete containing IOT. Test results indicated that the slump values of 130 mm and 80 to 110 mm were recorded for the control and IOT concretes respectively. The concrete sample of 50% IOT recorded the highest compressive strength of 37.7 MPa at 28 days, and the highest flexural strength of 5.5 MPa compared to 4.7 MPa for reference concrete. The texture of the IOT is rough and angular which was able to improve the strength of the concrete

Strength and Microstructure of Concrete with Iron Ore Tailings as Replacement for River Sand

River Sand is one of the basic ingredients used in the production of concrete. Consequently, continuous consumption of sand in construction industry contributes significantly to depletion of natural resources. To achieve more sustainable construction materials, this paper reports the use of iron ore tailings (IOT) as replacement for river sand in concrete production. IOT is a waste product generated from the production of iron ore and disposed to land fill without any economic value. Concrete mixtures containing different amount of IOT were designed for grade C30 with water to cement ratio of 0.60. The percentage ratios of the river sand replacements by IOT were 25%, 50%, 75% and 100%. Concrete microstructure test namely, XRD and Field Emission Scanned Electron Microscopic/Energy dispersive X-ray Spectroscopy (FESEM/EDX) were conducted for control and IOT concretes in order to determine the interaction and performance of the concrete containing IOT. Test results indicated that the slump values of 130 mm and 80 to 110 mm were recorded for the control and IOT concretes respectively. The concrete sample of 50% IOT recorded the highest compressive strength of 37.7 MPa at 28 days, and the highest flexural strength of 5.5 MPa compared to 4.7 MPa for reference concrete. The texture of the IOT is rough and angular which was able to improve the strength of the concrete