scholarly journals Behaviour of Compacted Filtered Iron Ore Tailings–Portland Cement Blends: New Brazilian Trend for Tailings Disposal by Stacking

2022 ◽  
Vol 12 (2) ◽  
pp. 836
Author(s):  
Nilo Cesar Consoli ◽  
Jordanna Chamon Vogt ◽  
João Paulo Sousa Silva ◽  
Helder Mansur Chaves ◽  
Hugo Carlos Scheuermann Filho ◽  
...  
Keyword(s):  
Portland Cement ◽  
Iron Ore ◽  
Triaxial Compression ◽  
Shear Stiffness ◽  
Friction Angle ◽  
Pulse Velocity ◽  
Design Parameters ◽  
Compression Tests ◽  
Tailings Disposal ◽  
Iron Ore Tailings

Failures of tailings dams, primarily due to liquefaction, have occurred in Brazil in recent years. These events have prompted the Brazilian government to place restrictions on the construction of new dams, as iron ore tailings deposited behind upstream dams by spigotting have been shown to have low in situ densities and strengths and are prone to failure. This work proposes a new trend for tailings disposal: stacking compacted filtered ore tailings–Portland cement blends. As part of the proposal, it analyses the behaviour of compacted iron ore tailings–Portland cement blends, considering the use of small amounts of Portland cement under distinct compaction degrees. With the intention of evaluating the stress–strain–strength–durability behaviour of the blends, the following tests were carried out: unconfined compression tests; pulse velocity tests; wetting–drying tests; and standard drained triaxial compression tests with internal measurement of strains. This is the first study performed to determine the strength and initial shear stiffness evolution of iron ore tailings–Portland cement blends during their curing time, as well friction angle and cohesion intercept. This manuscript postulates an analysis of original experimental results centred on the porosity/cement index (η/Civ). This index can help select the cement quantity and density for important design parameters of compacted iron ore tailings–cement blends required in geotechnical engineering projects such as the proposed compacted filtered iron ore tailings–cement blends stacking.

Iron Ore Tailing as Addition to Partial Replacement of Portland Cement

2018 ◽  
Vol 930 ◽  
pp. 125-130 ◽  
Author(s):  
Luciano Fernandes de Magalhães ◽  
Isabella de Souza Morais ◽  
Luis Felipe dos Santos Lara ◽  
Domingos Sávio de Resende ◽  
Raquel Maria Rocha Oliveira Menezes ◽  
...  
Keyword(s):  
Portland Cement ◽  
Iron Ore ◽  
Mineral Exploration ◽  
Planetary Mill ◽  
Open Pit ◽  
Partial Replacement ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
Open Pit Mines ◽  
Iron Ore Tailing

The manufacture of Portland cement used in the production of concrete emits large amounts of CO2into the atmosphere, contributing to the increase of the greenhouse effect. The environmental impact generated by the mineral exploration activity is a problem of easy verification, especially in open pit mines. The present work evaluated the possibility of using iron ore tailing as an addition to the partial replacement of the cement in mortars. The iron ore tailings were processed by drying in oven (48h at 105oC) and milling in a planetary mill (10min at 300RPM), obtaining medium grain size of 14,13 μm. For the characterization, laser granulometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal and thermogravimetric analysis (DTA / TGA) were performed. The sample is composed predominantly by quartz, hematite, goethite and gibbsite. After the characterization, the waste was used in the preparation of test specimens, with 10, 20 and 30% weight substitution of the cement. The composites were submitted to compression tests, with ages of 3, 7 and 28 days, using a strength rate of 0,25MPa/s. The mortars with 10, 20 and 30% of substitution presented resistance of 41.65, 36.26 and 31.64 MPa, being able to be characterized as category of Portland cement of resistance 40, 32 and 25 respectively. Considering the reduction of cement in the mortars produced, the results of compressive strength were relevant for the substitutions. The cements produced with the substitutions according to the Brazilian standards under the mechanical aspect can be classified as Portland cement.

scholarly journals Triaxial Testing of Geosynthetics Reinforced Tailings with Different Reinforced Layers

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1943
Author(s):  
Fu Yi ◽  
Changbo Du
Keyword(s):  
Triaxial Compression ◽  
Friction Angle ◽  
Confining Pressure ◽  
Test Results ◽  
Compression Tests ◽  
Strength Index ◽  
Stress Strain ◽  
High Confining Pressure ◽  
Zhang Model ◽  
Triaxial Compression Tests

To evaluate the shear properties of geotextile-reinforced tailings, triaxial compression tests were performed on geogrids and geotextiles with zero, one, two, and four reinforced layers. The stress–strain characteristics and reinforcement effects of the reinforced tailings with different layers were analyzed. According to the test results, the geogrid stress–strain curves show hardening characteristics, whereas the geotextile stress–strain curves have strain-softening properties. With more reinforced layers, the hardening or softening characteristics become more prominent. We demonstrate that the stress–strain curves of geogrids and geotextile reinforced tailings under different reinforced layers can be fitted by the Duncan–Zhang model, which indicates that the pseudo-cohesion of shear strength index increases linearly whereas the friction angle remains primarily unchanged with the increase in reinforced layers. In addition, we observed that, although the strength of the reinforced tailings increases substantially, the reinforcement effect is more significant at a low confining pressure than at a high confining pressure. On the contrary, the triaxial specimen strength decreases with the increase in the number of reinforced layers. Our findings can provide valuable input toward the design and application of reinforced engineering.

scholarly journals Relation between the Friction Angle of Sand at Triaxial Compression and Triaxial Extension and Plane Strain Conditions

Geosciences ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 29 ◽  
Author(s):  
Zenon Szypcio
Keyword(s):  
Plane Strain ◽  
Soil Mechanics ◽  
Triaxial Compression ◽  
Deformation Mode ◽  
Friction Angle ◽  
Failure Criteria ◽  
Compression Tests ◽  
Laboratory Test Results ◽  
Experimental Findings ◽  
Triaxial Extension

The strength of sand is usually characterized by the maximum value of the secant friction angle. The friction angle is a function of deformation mode, density, and stress level and is strongly correlated with dilatancy at failure. Most often, the friction angle is evaluated from results of conventional compression tests, and correlation between the friction angle of sand at triaxial compression and triaxial extension and plane strain conditions is a vital problem of soil mechanics. These correlations can be obtained from laboratory test results. The failure criteria for sand presented in literature also give the possibility of finding correlations between friction angles for different deformation modes. The general stress-dilatancy relationship obtained from the frictional state concept, with some additional assumptions, gives the possibility of finding theoretical relationships between the friction angle of sand at triaxial compression and triaxial extension and plane strain conditions. The theoretically obtained relationships presented in the paper are fully consistent with theoretical and experimental findings of soil mechanics.

Influence of Water Contents on Shear Strength of Rammed Earth Wall of Earth-Building

2011 ◽  
Vol 382 ◽  
pp. 172-175
Author(s):  
Ren Wei Wu ◽  
Xing Qian Peng ◽  
Li Zhang
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Triaxial Compression ◽  
Friction Angle ◽  
World Heritage Site ◽  
Rammed Earth ◽  
Compression Tests ◽  
Rammed Earth Wall ◽  
Influence Of Water ◽  
Water Contents

As the "Fujian earth-building" have been inscribed by UNESCO in 2008 as World Heritage Site, attentions of protection about the "Fujian earth-building" has getting more and more. This article takes samples of a rammed-earth wall from Yongding earth-buildings and determines the shear strength of the samples with different water content through triaxial compression tests. The influence on shear strength of water content of rammed-earth samples is analyzed. Test results show that the shear strength of rammed-earth has much to do with the water content of the soil, the greater the water content is，the smaller the shear strength is. With water content increasing, cohesion and internal friction angle of rammed-earth were decreases, and its changing trend is of marked characteristic of stage. When water contents of rammed-earth is under some value, its cohesion changes in small ranges; when water contents of rammed-earth is over the value, its cohesion decreases with water content increasing.

scholarly journals Shear Characteristics of Cement-Stabilized Sand Reinforced with Waste Polyester Fiber Fabric Blocks

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Xiangfeng Lv ◽  
Hongyuan Zhou
Keyword(s):  
Low Cost ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Polyester Fiber ◽  
Peak Strain ◽  
Compression Tests ◽  
Initial Stiffness ◽  
Cemented Sand ◽  
Aspect Ratios ◽  
Fiber Fabric

The present paper is devoted to investigate the effects of waste polyester fiber fabric blocks on the strength and mechanical behavior of cemented sand. In the investigation, samples were prepared at four different percentages of waste polyester fiber fabric block content (0.0%, 0.5%, 1.0%, and 1.5% by weight of soil) and two different aspect ratios (2 : 1 and 3 : 1), and conventional triaxial compression tests were carried out after the curing period. The test results indicated that the addition of fibers increased peak and residual shear strengths of cemented sand and changed its brittle behavior to a more ductile one. As the fabric block content increased, the brittleness index and initial stiffness decreased, and the peak strain and internal friction angle increased. The optimal combination of the content and aspect ratio was determined to be 0.5% and 3 : 1. The integration of the fabric blocks with the cemented sand matrix was analyzed by using the scanning electron microscopy (SEM). It is found that the reinforcement effect is related to the bond strength and friction at the interface. The micromechanical properties of the fiber/matrix interface were influenced by the undulations between the fabric block components. In summary, this study presented a low-cost and environment-friendly method for reinforcing cement-stabilized sand.

scholarly journals Utilization of Iron Ore Tailings as Raw Material for Portland Cement Clinker Production

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Li Luo ◽  
Yimin Zhang ◽  
Shenxu Bao ◽  
Tiejun Chen
Keyword(s):  
Portland Cement ◽  
Iron Ore ◽  
Mechanical Performance ◽  
Mineralogical Composition ◽  
Cement Industry ◽  
Raw Material ◽  
Cement Clinker ◽  
Iron Ore Tailings ◽  
Portland Cement Clinker ◽  
Clinker Production

The cement industry has for some time been seeking alternative raw material for the Portland cement clinker production. The aim of this research was to investigate the possibility of utilizing iron ore tailings (IOT) to replace clay as alumina-silicate raw material for the production of Portland cement clinker. For this purpose, two kinds of clinkers were prepared: one was prepared by IOT; the other was prepared by clay as a reference. The reactivity and burnability of raw meal, mineralogical composition and physical properties of clinker, and hydration characteristic of cement were studied by burnability analysis, differential thermal analysis, X-ray diffraction, and hydration analysis. The results showed that the raw meal containing IOT had higher reactivity and burnability than the raw meal containing clay, and the use of IOT did not affect the formation of characteristic mineralogical phases of Portland cement clinker. Furthermore, the physical and mechanical performance of two cement clinkers were similar. In addition, the use of IOT was found to improve the grindability of clinker and lower the hydration heat of Portland cement. These findings suggest that IOT can replace the clay as alumina-silicate raw material for the preparation of Portland cement clinker.

scholarly journals Experimental Investigation on Failure Modes and Mechanical Properties of Rock-Like Specimens with a Grout-Infilled Flaw under Triaxial Compression

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Huilin Le ◽  
Shaorui Sun ◽  
Feng Zhu ◽  
Haotian Fan
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Epoxy Resin ◽  
Failure Modes ◽  
Shear Failure ◽  
Fractured Rock ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Confining Pressure ◽  
Compression Tests

Flaws existing in rock mass are one of the main factors resulting in the instability of rock mass. Epoxy resin is often used to reinforce fractured rock mass. However, few researches focused on mechanical properties of the specimens with a resin-infilled flaw under triaxial compression. Therefore, in this research, epoxy resin was selected as the grouting material, and triaxial compression tests were conducted on the rock-like specimens with a grout-infilled flaw having different geometries. This study draws some new conclusions. The high confining pressure suppresses the generation of tensile cracks, and the failure mode changes from tensile-shear failure to shear failure as the confining pressure increases. Grouting with epoxy resin leads to the improvement of peak strengths of the specimens under triaxial compression. The reinforcement effect of epoxy resin is better for the specimens having a large flaw length and those under a relatively low confining pressure. Grouting with epoxy resin reduces the internal friction angle of the samples but improves their cohesion. This research may provide some useful insights for understanding the mechanical behaviors of grouted rock masses.

Isothermal modeling of sand–bentonite mixtures at elevated temperatures

1995 ◽  
Vol 32 (1) ◽  
pp. 78-88 ◽  
Author(s):  
B.E. Lingnau ◽  
J. Graham ◽  
N. Tanaka
Keyword(s):  
Shear Strength ◽  
Elevated Temperatures ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Compression Tests ◽  
Strain Behavior ◽  
Bentonite Buffer ◽  
State Boundary ◽  
Increasing Temperature ◽  
Triaxial Compression Tests

Two models are proposed for describing the stress–strain behavior of sand–bentonite (buffer) mixtures at elevated temperatures: (1) isothermal pseudoelasticity and (2) isothermal elastic-plasticity. Data to support the models come from consolidated undrained triaxial compression tests performed on dense saturated buffer specimens at effective confining stresses up to 9.0 MPa and temperatures of 26°, 65°, and 100 °C. Measurements indicate that volumes decrease with increasing temperature if the tests are carried out under drained conditions. These trends can be modelled by a family of hardening lines in semilog compression space. Power law relationships are presented for undrained shear-strength envelopes that increase in size with an increase in temperature. The slopes of unload-reload lines, κ, in semilog compression space vary with temperature and can be related to systematic variation in the friction angle [Formula: see text]. The shear modulus G50 at 50% peak strength also depends on temperature. Several plotting techniques are used to show the existence of different state boundary surfaces for each test temperature. Key words : sand–bentonite, buffer, compression, shear strength, temperature, modelling.

scholarly journals Numerical Triaxial Apparatus and Application

2013 ◽  
Vol 353-356 ◽  
pp. 3251-3255 ◽  
Author(s):  
Xiao Liang Wang ◽  
Jia Chun Li
Keyword(s):  
Granular Materials ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Good Prediction ◽  
Strain Response ◽  
Compression Tests ◽  
Dilatancy Angle ◽  
Triaxial Apparatus ◽  
Dem Model

A numerical triaxial apparatus based on discrete element method is developed on the platform of Yade using Python script. A DEM model with rolling resistance contact considered is proposed for dense granular materials, which is then applied in triaxial compression test of Chende sand. Stress-strain response and volume-axial strain response of the DEM model agree well with that of experiments, with a good prediction of dilatancy angle. Degradation of granular materials duo to particle erosion is also investigated using triaxial compression tests. It is indicated that peak friction angle decreases with the remove of particles if strong force network of granular materials is destroyed.

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