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Literatura académica sobre el tema "Cemented paste backfills"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 4 de febrero de 2022

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Artículos de revistas sobre el tema "Cemented paste backfills"

Niroshan, Naguleswaran, Nagaratnam Sivakugan y Ryan Llewellyn Veenstra. "Laboratory Study on Strength Development in Cemented Paste Backfills". Journal of Materials in Civil Engineering 29, n.º 7 (julio de 2017): 04017027. http://dx.doi.org/10.1061/(asce)mt.1943-5533.0001848.

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Zhang, Xinguo, Jinhai Zhao, Lin Xin, Kun Wang y Haiyang Pan. "Monitoring and Assessment of Cemented Paste Backfill Containing Coal Gangue and Fly Ash in an Underground Mine". Advances in Materials Science and Engineering 2021 (23 de febrero de 2021): 1–15. http://dx.doi.org/10.1155/2021/5946148.

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Cemented coal gangue paste backfill (CCGPB) containing coal gangue and fly ash is a backfilling technique newly developed in coal mines in China that allows environmentally hazardous products, such as gangue and fly ash, to be reused in underground stopes. CCGPB materials provide efficient ground support for the caving of strata and reduce surface subsidence. In this paper, field monitoring of CCGPB properties was conducted in an underground coal mine, which mainly included the measurement of the longwall face temperature, humidity, CCGPB internal hydration temperature, stress conditions inside the backfills, and displacement. First, the components of the backfills, paste technique, slurry generation procedures, coalfield geology, and mining conditions were introduced. Then, a monitoring system was designed in the field. An online monitoring system was installed. The results of the field monitoring showed that the curing temperature significantly varied, i.e., from 26°C near the main gate to 37°C near the tailgate. The curing humidity had the same trends, increasing from 60% relative humidity (RH) near the main gate to 81% RH near the tailgate. The internal hydration process of the paste was divided into four stages, i.e., the rapid hydration stage, slower hydration stage, rapid decline hydration stage, and relatively stable stage. The highest hydration temperature was 50°C, which was measured on the second day after the backfill process. The temperature approached stability at 41°C. The evolution of the roof stress applied on the CCGPB was divided into four stages: the development stage, regulation stage, rapid growth stage, and relatively stable stage. The maximum roof loading was 12 MPa in the middle of the longwall face. The deformation of the backfill experienced four stages, i.e., the rapid deformation stage, slow deformation stage, relatively stable stage, and long-term stable stage. The maximum deformation was 104.3 mm, appearing in the middle of the face. In addition, the compression ratio of the backfill was approximately 4%. The results of this study showed that the working conditions of backfills in the field were different from those in the laboratory. This paper provides guidance for the design of the CCGPB technique and the predictions of surface subsidence induced by the production process of underground mining.

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Ouattara, Drissa, Ammar Yahia, Mamert Mbonimpa y Tikou Belem. "Effects of superplasticizer on rheological properties of cemented paste backfills". International Journal of Mineral Processing 161 (abril de 2017): 28–40. http://dx.doi.org/10.1016/j.minpro.2017.02.003.

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Yilmaz, Erol, Tikou Belem y Mostafa Benzaazoua. "Study of physico-chemical and mechanical characteristics of consolidated and unconsolidated cemented paste backfills". Gospodarka Surowcami Mineralnymi - Mineral Resources Management 29, n.º 1 (1 de marzo de 2013): 81–100. http://dx.doi.org/10.2478/gospo-2013-0006.

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Streszczenie W ostatnich latach obserwuje się, że wydajność i jakość próbek zawiesin nasyconych cementem (CPB - Cement Paste Backfill) in situ są stale niższe niż tych samych próbek przygotowanych w plastikowych formach w laboratorium. Może to wynikać z braku w laboratorium skutecznego narzędzia mogącego naśladować zawiesiny in situ, warunki ich utwardzania jak również rozmiary i geometrię próbek. W celu wypełnienia tej luki, w laboratorium opracowano nowe narzędzie o nazwie CUAPS (Curing Under Applied Pressure System), wytworzone i wykorzystane do zbadania wpływu ciśnienia na podstawie skutecznego nacisku na właściwości fizykochemiczne i mechaniczne CPB, jak również próbek otrzymanych z plastikowych form. Badania porównawcze przeprowadzono zarówno dla próbek CUAPS jak i próbek otrzymanych w laboratorium, zawierających lepiszcza (cementu) 3,45 i 7% wag. po 7, 14 i 28 dniach utwardzania. Wyniki wskazują, że wydajność próbek konsolidowanych CUAPS są zawsze bardziej prawdziwe (realistyczne) niż próbek otrzymanych w laboratorium, głównie z powodu odprowadzania wody w wyniku konsolidacji. Ostatecznie metoda CUAPS powoduje korzystny wpływ na utwardzenie CPB dzięki zawartości wody (separacja wody od świeżej zawiesiny odpadów z cementu) i połączeniu części wody zasobowej z zawiesiną w zrobach.

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Coussy, Samuel, Dogan Paktunc, Jérôme Rose y Mostafa Benzaazoua. "Arsenic speciation in cemented paste backfills and synthetic calcium–silicate–hydrates". Minerals Engineering 39 (diciembre de 2012): 51–61. http://dx.doi.org/10.1016/j.mineng.2012.05.016.

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Fall, Mamadou y Mukesh Pokharel. "Coupled effects of sulphate and temperature on the strength development of cemented tailings backfills: Portland cement-paste backfill". Cement and Concrete Composites 32, n.º 10 (noviembre de 2010): 819–28. http://dx.doi.org/10.1016/j.cemconcomp.2010.08.002.

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Zhao, Yue, Amin Soltani, Abbas Taheri, Murat Karakus y An Deng. "Application of Slag–Cement and Fly Ash for Strength Development in Cemented Paste Backfills". Minerals 9, n.º 1 (30 de diciembre de 2018): 22. http://dx.doi.org/10.3390/min9010022.

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The present study investigates the combined capacity of a newly developed slag-blended cement (MC) and fly ash (FA) as a sustainable solution towards improving the mechanical performance of the cemented paste backfill (CPB) system of a copper-gold underground mine. A total of thirteen mix designs consisting of three MC-treated and ten MC + FA-treated blends were examined. Samples were prepared with a solids content of 77% (by total mass), and were allowed to cure for 7, 14, 28, 56 and 128 days prior unconfined compression testing. Scanning electron microscopy (SEM) studies were also carried out to observe the evolution of fabric in response to MC and MC + FA amendments. The greater the MC content and/or the longer the curing period, the higher the developed strength, toughness and stiffness. The exhibited improvements, however, were only notable up to 56 days of curing, beyond of which the effect of curing was marginal. The performance of 4% Portland cement or PC (by total dry mass) was found to be similar to that of 1.5% MC, while the higher MC inclusions of 2.5% and 3%, though lower in terms of binder content, unanimously outperformed 4% PC. The use of FA alongside MC improved the bonding/connection interface generated between the tailings aggregates, and thus led to improved mechanical performance compared with similar MC inclusions containing no FA. Common strength criteria for CPBs were considered to assess the applicability of the newly introduced MC and MC + FA mix designs. The mix designs “3% MC” and “2.5% MC + 2–2.5% FA” satisfied the 700 kPa strength threshold required for stope stability, and thus were deemed as optimum design choices.

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Yilmaz, Erol. "Stope depth effect on field behaviour and performance of cemented paste backfills". International Journal of Mining, Reclamation and Environment 32, n.º 4 (7 de febrero de 2017): 273–96. http://dx.doi.org/10.1080/17480930.2017.1285858.

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Coussy, Samuel, Mostafa Benzaazoua, Denise Blanc, Pierre Moszkowicz y Bruno Bussière. "Arsenic stability in arsenopyrite-rich cemented paste backfills: A leaching test-based assessment". Journal of Hazardous Materials 185, n.º 2-3 (enero de 2011): 1467–76. http://dx.doi.org/10.1016/j.jhazmat.2010.10.070.

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Zhao, Taheri, Soltani, Karakus y Deng. "Strength Development and Strain Localization Behavior of Cemented Paste Backfills Using Portland Cement and Fly Ash". Materials 12, n.º 20 (9 de octubre de 2019): 3282. http://dx.doi.org/10.3390/ma12203282.

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This study examines the combined performance of Portland cement (PC), the binder, and fly ash (FA), the additive, towards improving the mechanical performance of the South Australian copper-gold underground mine cemented paste backfill (CPB) system. A series of unconfined compressive strength (UCS) tests were carried out on various mix designs to evaluate the effects of binder and/or additive contents, as well as curing time, on the CPB’s strength, stiffness and toughness. Moreover, the failure patterns of the tested samples were investigated by means of the three-dimensional digital image correlation (DIC) technique. Making use of several virtual extensometers, the state of axial and lateral strain localization was also investigated in the pre- and post-peak regimes. The greater the PC content and/or the longer the curing period, the higher the developed strength, stiffness and toughness. The use of FA alongside PC led to further strength and stiffness improvements by way of inducing secondary pozzolanic reactions. Common strength criteria for CPBs were considered to assess the applicability of the tested mix designs; with regards to stope stability, 4% PC + 3% FA was found to satisfy the minimum 700 kPa threshold, and thus was deemed as the optimum choice. As opposed to external measurement devices, the DIC technique was found to provide strain measurements free from bedding errors. The developed field of axial and lateral strains indicated that strain localization initiates in the pre-peak regime at around 80% of the UCS. The greater the PC (or PC + FA) content, and more importantly the longer the curing period, the closer the axial stress level required to initiate localization to the UCS, thus emulating the failure mechanism of quasi-brittle materials such as rock and concrete. Finally, with an increase in curing time, the difference between strain values at the localized and non-localized zones became less significant in the pre-peak regime and more pronounced in the post-peak regime.

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Tesis sobre el tema "Cemented paste backfills"

Han, Fa Sen. "Geotechnical Behaviour of Frozen Mine Backfills". Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20250.

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This thesis presents the results of an investigation of factors which influence the geotechnical properties of frozen mine backfill (FMB). FMB has extensive application potential for mining in permafrost areas. The uniaxial compressive strength (UCS) of hardened backfill is often used to evaluate mine backfill stability. However, the deformation behaviour and stiffness of the FMB are also key design properties of interest. In this thesis, uniaxial compressive tests were conducted on FTB and FCPB samples. Information about the geotechnical properties of FMB is obtained. The effects of FMB mix components and vertical compression pressure on the geotechnical properties of FMB are discussed and summarized. An optimum total water content of 25%-35% is found in which the strength and the modulus of elasticity of the FTB are 1.4-3.2 MPa and 35-58 MPa, respectively. It is observed that a small amount (3-6%) of cement can significantly change the geotechnical properties of FTB.

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Aldhafeeri, Zaid. "Reactivity of Cemented Paste Backfill". Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38111.

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Mining has been one of the main industries in the course of the development of human civilization and economies of various nations. However, every industry has issues, and one of the problems the mining industry has faced is the management of waste, especially sulphide-bearing tailings, which are considered to be a global environmental problem. This issue puts pressure on the mining industry to seek alternative approaches for tailings management. Among the several different types of methods used, cemented paste backfilling is one of the technologies that offers good management practices for the disposal of tailings in underground mines worldwide. Cemented paste backfill (CPB) is a cementitious composite made from a mixture of mine tailings, water and binder. This technology offers several advantages, such as improving the production and safety conditions of underground mines. Among these advantages, CPB is a promising solution for the management of sulphidic tailings, which are considered to be reactive materials (i.e., not chemically stable in an atmospheric condition) and the main source of acid mine drainage, which constitutes a serious environmental challenge faced by mining companies worldwide. Such tailings, if they come into direct contact with atmospheric elements (mainly oxygen and water), face oxidation of their sulphidic minerals, thus causing the release of acidic drainage (i.e., acid mine drainage) and several types of heavy metals into surrounding water bodies and land. Therefore, the reactivity of sulphidic tailings with and without cement content can be considered as a key indicator of the environmental behavior and durability performance of CPB systems. For a better understanding of the reactivity, it is important to investigate the influencing factors. In this research, several influencing factors are experimentally studied by conducting oxygen consumption tests on different sulphidic CPB mixtures as well as their tailings under different operational and environmental conditions. These factors include time, curing temperature, initial sulphate content, curing stress, mechanical damage, binder type and content, and the addition of mineral admixtures. In addition, several microstructural techniques (e.g., x-ray diffraction and scanning electron microscopy) are applied in order to understand the changes in the CPB matrices and identify newly formed products. The results reveal that the reactivity of CPB is affected by several factors (e.g., curing time, initial sulphate content, ageing, curing and atmospheric temperature, binder type and content, vertical curing stress, filling strategy, hydration and drainage, etc.), either alone or in combination. These factors can affect reactivity either positively or negatively. It is observed that CPB reactivity decreases with increasing curing time, temperature (i.e., curing and atmospheric temperatures), curing stress, binder content, the addition of mineral admixtures, degree of saturation, and the binder hydration process, whereas reactivity increases with increases in sulphide minerals (e.g., pyrite), initial sulphate content, mechanical damage, and with decreased degrees of saturation and binder content. The effect of sulphate on the reactivity of CPB is based on the initial sulphate content as well as curing time and temperature. It is concluded that the reactivity of CPB systems is time- and temperature-dependent with respect to other factors. Also, binders play a significant role in lowering CPB reactivity due to their respective hydration processes.

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Bull, Andrew. "Temperature Dependence of the Leachability of Cemented Paste Backfill". Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/38866.

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Underground mining is a mineral acquisition technique that is critical to global economies, and human technological advancements. As shallow resource reserves are depleted, mine depths are increasing to accommodate global mineral demand. Increases in mine throughputs and excavation depths pose increased environmental concerns. Tailings surface disposal, and underground mine support are two considerable environmental and geotechnical factors of concern in current day mining. Underground waste disposal has been adopted by the mining industry in many forms. Cemented paste backfill (CPB) is a common best management practice developed to tackle these two specific resource industry related issues worldwide. CPB is a cement-stabilized material composed of tailings, water, and hydraulic binder. Tailings disposal areas on the earth’s surface are reduced by disposing of tailings in subsurface stopes that have been previously excavated. This increases underground safety by providing structural support to the mine. There are also economic benefits to this practice, as the additional support allows for adjacent pillars to be excavated. Although CPB greatly reduces tailings exposure to atmospheric elements, there are still underground environmental factors that must be considered with respect to environmental performance. CPBs are porous media, meaning they are susceptible to leaching of naturally occurring metals that are no longer in a stable condition as they were when incorporated in the parent rock. Arsenic and lead are metals of concern due to their association with many ore bodies. Leaching of these unstable metals may be influenced by the backfill curing temperature and the chosen hydraulic binder. Curing temperatures may be influenced by geographic location, local stope geology and depth, hydration and transport, among others. Hydraulic binders are chosen based on availability, cost, and desired mechanical properties of the paste. In this research, the effect of curing temperature and binder composition on the leachability of CPB are studied. ASTM C 1308 leaching protocol is used to determine the leachability of six CPBs. In addition, microstructural techniques (Powder X-Ray Diffraction, Mercury Intrusion Porosimetry, and Scanning Electron Microscopy) are used to relate the microstructural properties of the CPB to the leaching characteristics. Results reveal that CPBs cured with ordinary Portland cement (OPC) leach significantly less than CPBs cured with an OPC/Blast furnace slag (Slag) binder (50% blending ratio) as a result of CH consumption in slag hydration. Both CH and C-S-H are responsible for immobilizing arsenic in cement stabilized materials. OPC-CPBs contain greater relative quantities of CH, which aids in arsenic immobilization. Between the range of 2°C and 35°C OPC-CPB performed better at lower curing temperatures. Lower curing temperatures are favoured in OPC-CPB because the pore surface greater than the threshold pore diameter is reduced. Alternatively, OPC/Slag-CPB exhibited a decrease in cumulative mass leached at higher curing temperatures. The difference in cumulative mass leached by the OPC/Slag-CPBs is also related to the pore surface, and threshold pore diameter.

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Cui, Liang. "Multiphysics Modeling and Simulation of the Behavior of Cemented Tailings Backfill". Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36145.

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One of the most novel technologies developed in the past few decades is to convert mine wastes into cemented construction materials, otherwise known as cemented tailings backfill (CTB). CTB is an engineered mixture of tailings (waste aggregates), water and hydraulic binders. It is extensively used worldwide to stabilize underground cavities created by mining operations and maximize the recovery of ore from pillars. Moreover, the application of CTB is also an environmentally friendly means of disposing potential acid generating tailings underground. During and after its placement into underground mine excavations or stopes, complex multiphysics processes (including thermal, T, hydraulic, H, mechanical, M, and chemical, C, processes) take place in the CTB mass and thus control its behavior and performance. With the interaction of the multiphysics processes, the field variables (temperature, pore water pressure, stress and strain) and geotechnical properties of CTB undergo substantial changes. Therefore, the prediction of the field performance of CTB structures during their life time, which has great practical importance, must incorporate these THMC processes. Moreover, the self-weight effect, water drainage through barricades, thermal expansion and chemical shrinkage can contribute to the volumetric deformation of CTB. Consequently, CTB exhibits unique consolidation behavior compared to conventional geomaterials (e.g., soil). Furthermore, the consolidation processes can result in relative displacement between the rock mass and CTB. The resultant rock mass/CTB interface resistance can reduce the effects of the overburden pressure or the vertical stress (i.e., arching effect). Hence, a full understanding, through multiphysics modeling and simulation of CTB behaviors, is crucial to reliably assess and predict the performance of CTB structures. Yet, there are currently no models or tools to predict the fully coupled multiphysics behavior of CTB. In this Ph.D. study, a series of mathematical models which include an evolutive elastoplastic model, a fully coupled THMC model, a multiphysics model of consolidation behavior and a multiphysics model of the interaction between the rock mass/CTB interface are developed and validated. There is excellent agreement between the modeled results and experimental and/or in-situ monitored data, which proves the accuracy and predictive ability of the developed models. Furthermore, the validated multiphysics models are applied to a series of engineering issues, which are relevant for the field design of CTB structures, to investigate the self-desiccation process, consolidation behavior of CTB structures as well as to assess the pressure on barricades and the strength development in CTB structures. The obtained results show that CTB has different behaviors and performances under different backfilling conditions and design strategies, and the developed multiphysics models can accurately model CTB field behavior. Therefore, the research conducted in this Ph.D. study provides useful tools and technical information for the optimal design of CTB structures.

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Hughes, Paul B. "Design guidelines : underhand cut and fill cemented paste backfill sill beams". Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/47089.

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Difficult ground conditions negatively affect both mine production and the safety of underground workers. Underhand cut-and-fill mining is a potential solution to these issues. Discussions with mine sites revealed the use of sill beams in underhand cut-and-fill mining is not optimized. Optimization in ground support, development of in-situ strength test, and revisions of design standards are desired. Ultimately, the operations require the minimum cemented paste backfill (CPB) strength for a stable span. Operational concerns were addressed by a multi-prong approach investigating stability of CPB sill beams using observational, experimental and analytical techniques. A case study approach summarizing the design of five mines utilizing underhand cut-and-fill with CPB is presented for different ground conditions. A historical study of span widths and beam strengths for the Stillwater mine is presented. Laboratory testing determined the stress-strain behaviour of CPB. CPB follows a hyperbolic elastic loading path to peak stress followed by a strain-softening associated with the decay of the cohesion values. Additional testing found that cohesive and tensile strength values were on average 35 and 20 percent respectively of the unconfined compressive strength. This finding impacts sill beam design strengths as previous assumptions were conservative. Test database analyses from three mine sites found that sample size and location preparation has no effect on the strength of the sample. In-situ testing methods common in other industries were not practical with CPB; rather the in-situ strength can be represented by a site specific moisture content index relationship. Review of current design methodology noted closure stresses were absent from the majority; a method was developed to assess closure for sill beam stability. The potential for critical failures were determined through a Monte Carlo probabilistic model. Methods reducing the risk of failure based on the simulation are investigated. Analysis found ground support does not improve the structural stability of the sill beam. Ground support keeps the beam intact: beam equations govern stability. The stability of sill beam in a seismic environment was analyzed based on the strain-energy density of the beam. The research concludes with a design guideline for CPB sill beams.

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Chang, Shuang. "Strength and Deformation Behaviour of Cemented Paste Backfill in Sub-zero Environment". Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34754.

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Underground mining produces a huge amount of voids and an even larger quantity of mine waste. Overlooking these voids could lead to the possibility of ground subsidence, as well as safety issues during mining operation; while ignoring the waste, could cause environmental pollution and significant suffering. One solution to remedy both (the voids and the waste) is cemented paste backfill (CPB), which is gaining increased recognition in both the mining industry and academic research. Transforming tailings into cemented paste, and transporting this back to underground stopes, not only negates these safety issues to a large degree, but also makes it possible to put waste to good use.However, most studies involving CPB have been conducted at temperatures above 0°C; knowledge of CPB in sub-zero environments is still lacking. For this reason, this thesis investigates the mechanical behaviour of CPB in a the latter type of environment.Uniaxial compressive strength tests were carried out on a series of frozen CPB (FCPB) samples to evaluate the mechanical behaviour (e.g. compressive strengths, geotechnical features, and the stress-strain relationships) of FCPB. It has been discovered in this thesis that FCPB exhibits remarkable strength compared to CPB and, has a great resemblance to frozen soil. Factors which may affect the behaviour of FCPB were thoroughly examined. Binder contents and types were found to be irrelevant; water content, in contrast, plays a dominant role, with an optimum value of around 26% by weight. Sulphate was confirmed to have an adverse effect on the strength of FCPB due to the increasing unfrozen water content and the formation of legible ice lenses. Hydraulic conductivity tests, scanning electron microscope observations, thermal gravimetric analyses, and mercury intrusion porosimetry were also performed as subsidiary experiments to understand the geotechnical features of FCPB. This information will be of significant value for numerous practical applications.

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Mohammad, Pour Hoda. "Strength and Environmental Properties of Cemented Paste Backfill That Contains Sodium Silicate". Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40966.

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Mining is an important industry that plays a significant role in the development of human civilization and economies. However, the underground mining process produces a large volume of mine wastes (e.g., tailings) as well as creates large voids that require filling, typically with an engineering backfill material. Filling the voids with mine waste materials provides an environmental-friendly way of disposing mining waste. It is also an effective way of increasing ore recovery and improving the safety of miners. One of the best techniques of mine backfill is called cemented paste backfill (CPB), which is typically a mixture of tailings, binder and water. The most common binder used in the preparation of CPB is Portland cement (PC). PC is not only a costly binder, but its production is highly energy-intensive and also generates a large amount of CO2. The cement consumption can represent up to 75% of the cost of CPB. These above-mentioned factors have compelled mining companies to seek for cement alternatives that enhance the engineering properties of the CPB, decrease the cement content and reduce the carbon footprint of the mining industry. Sodium silicate is the most recent chemical additive that is proposed to reduce the binder content in CPB. Sodium silicate is an alkaline solution that is used to activate a pozzolanic material, such as cement, slag and Fly ash. However, the effect of sodium silicate on the strength and key environmental properties (permeability or saturated hydraulic conductivity, reactivity) of CPB is not well understood. The objective of this thesis is to investigate the possibility of using sodium silicate as an activator in cemented paste backfill and obtain an improvement in the aforementioned engineering properties of CPB. In order to determine the effect of the sodium silicate on backfill properties, some CPB testing methods were developed to fulfill the objectives of this research. Thus, the evolution of hydraulic, mechanical and microstructural properties of CPB samples containing sodium silicate (SS-CPB) have been tested or monitored at different curing ages (1, 3, 7, 28 and 90 days) and different CPB mixtures as well. The results of these studies show that activating CPB with sodium silicate develop CPB strength faster than CPB samples without sodium silicate. In addition, hydraulic conductivity and reactivity results show a positive change in samples containing sodium silicate compared to free sodium silicate CPB samples. Indeed, this activation leads to decreasing permeability and reactivity due to the formation of cement hydration products and acceleration of the binder hydration process. Moreover, binder type and content in the presence of sodium silicate as an alkali activator in the CPB play a significant role in lowering hydraulic conductivity and reactivity of CPB.

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Ghirian, Alireza. "Coupled Thermo-Hydro-Mechanical-Chemical (THMC) Processes in Cemented Tailings Backfill Structures and Implications for their Engineering Design". Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34605.

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The main result of underground mining extraction is creating of large underground voids (mine stopes). These empty openings are typically backfilled with an engineering cementitious material called cemented paste backfill (CPB). The main purpose of CPB application in underground mining is to provide stability and ensure the safety of underground openings, maximize ore recovery, and also provide an environmental-friendly means of underground disposal of potential acid generating tailings. CPB is a mixture of mine tailings, cement binder and water. CPB has a complex geotechnical behaviour when poured into mine voids. This is because of the different thermal (T), hydraulic (H), mechanical (M) and chemical coupled processes and interactions that take place in CPB soon after placement. In addition to these THMC behaviours, various external factors, such as stope geometry, drainage condition and arching effects add more complexity to its behaviour. In order to acquire a full understanding of CPB behaviour, there is a need to consider all of these THMC factors and processes together. So far, there has not been any study that addresses this research need. Indeed, fundamental knowledge of the THMC behaviour of CPB provides a key means for designing safe and cost-effective backfill structures, as well as optimizing mining cycles and productivity of mines. Innovative experimental tools and CPB testing methods have been developed and adopted in this research to fulfill the objectives of this research. In the first phase of the study, experiments with high columns are developed to study the THMC behaviour of CPB from early to advanced ages with respect to height of the column and curing time. The column experiments simulate the mine stope and filling sequence and provide an opportunity to study external factors, such as evaporation, on the THMC behaviour of CPB. However, an important factor is the overburden pressure from the stress due to self-weight that cannot be simulated through column experiments. Therefore, in the second phase of this study, a novel THMC curing under stress apparatus is developed to study the THMC behaviour of CPB under various pressures due to the self-weight of the CPB, drainage conditions, and filling rate and sequence. Comprehensive instrumentation and geotechnical testing are carried out to obtain fundamental knowledge on the THMC behaviour of CPB in different curing conditions from early to advanced ages. The results of these studies show that the THMC properties of CPB are coupled. Important parameters, such as curing stress, self-desiccation due to cement hydration, temperature, pore water chemistry, and mineralogical and chemical properties of the tailings, have significant influence on the shear strength and compressive strength development of CPB. Factors such as evaporation and drying iii shrinkage can also affect the hydro-mechanical properties of CPB. The curing conditions (such as curing stress, drainage and filling rate) also has significant impact on CPB behaviour and performance. The THMC interactions and the degree of influence of each factor should be included in designing backfill structures and planning mining cycles. This innovative curing under stress technique can be replaced the conventional curing of CPB (curing under zero stress and no THMC loadings), in order to optimize CPB mechanical strength assessment, increase mine safety and enhance the productivity.

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Alainachi, Imad Hazim. "Shaking Table Testing of Cyclic Behaviour of Fine-Grained Soils Undergoing Cementation: Cemented Paste Backfill". Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41524.

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Cemented paste backfill (CPB) is a novel technology developed in the past few decades to better manage mining wastes (such as tailings) in environmentally friendly way. It has received prominent interest in the mining industry around the world. In this technology, up to 60% of the total amount of tailings is reused and converted into cemented construction material that can be used for secondary support in underground mine openings (stopes) and to maximize the recovery of ore from pillars. CPB is an engineered mixture of tailings, water, and hydraulic binder (such as cement), that is mixed in the paste plant and delivered into the mine stopes either by gravity or pumping. During and after placing it into the mine stopes, the performance of CPB mainly depends on the role of the hydraulic binder, which increases the mechanical strength of the mixture through the process of cement hydration. Similar to other fine-grained soils undergoing cementations, CPB’s behavior is affected by several conditions or factors, such as cement hydration progress (curing time), chemistry of pore water, mixing and curing temperature, and filling strategy. Also, it has been found that fresh CPB placed in the mine stopes can be susceptible to many geotechnical issues, such as liquefaction under ground shaking conditions. Liquefaction-induced failure of CPB structure may cause injuries and fatalities, as well as significant environmental and economic damages. Many researches studied the effect of the aforementioned conditions on the static mechanical behavior of CPB. Other researches have evaluated the liquefaction behavior of natural soils and tailings (without cement) during cyclic loadings using shaking table test technique. Only few studies investigated the CPB liquefaction during dynamic loading events using the triaxial tests. Yet, there are currently no studies that addressed the liquefaction behavior of CPB under the previous conditions by using the shaking table technique. In this Ph.D. study, a series of shaking table tests were conducted on fresh CPB samples (75 cm × 75 cm ×70 cm), which were mixed and poured into a flexible laminar shear box (that was designed and build for the purpose of this research). Some of these shaking table tests were performed at different maturity ages of 2.5 hrs, 4.0 hrs, and 10.0 hrs, to investigate the effect of cement hydration progress on the liquefaction potential of CPB. Another set of tests were conducted to assess the effect of the chemistry (sulphate content) of the pore-water on the cyclic response of fresh CPB by exposing cyclic loads on couple of CPB models that contain different concertation of sulphate ions of 0.0 ppm and 5000 ppm. Moreover, as part of this study, series of shaking table test was conducted on CPB samples that were prepared and cured at different temperatures of 20oC and 35oC, to evaluate the effect of temperature of the cyclic behavior of CPB. Furthermore, the effect of filling strategy on the cyclic behavior of fresh CPB was assessed by conducting set of shaking tables tests on CPB models that were prepared at different filling strategies of continuous filling, and sequential or discontinuous (layered) filling. The results obtained show that CPB has different cyclic behavior and performance under these different conditions. It is observed that the progress of cement hydration (longer curing time) enhances the liquefaction resistance of CPB, while the presence of sulphate ions diminishes it. It is also found that CPB mixed and cured in low temperature is more prone to liquefaction than those prepared at higher temperatures. Moreover, the obtained results show that adopting the discontinuous (layered) filling strategy will improve the liquefaction resistance of CPB. The finding presented in this thesis will contribute to efficient, cost effective and safer design of CPB structures in the mine areas, and will help in minimizing the risks of liquefaction-induced failure of CPB structures.

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Celestin, Henry Jean Claude. "Geotechnical properties of cemented paste backfill and tailings liners: Effect of mix components and temperature". Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28080.

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Cemented Paste Backfill (CPB) is extensively used in underground mine operations. Several studies have been conducted to investigate the mechanical properties of CPB. However, little attention has been devoted to the thermal conductivity of CPB. The knowledge of this thermal property is vital for the design of cost-effective and durable CPB materials. This paper presents the results of a comprehensive laboratory study on the thermal conductivity of CPB. Influencing factors on the thermal conductivity of CPB were quantitatively investigated. The measurements of thermal conductivity were performed by using the KD2 Thermal Properties Analyzer. Valuable results with regards to the effects of CPB's mix components, curing time and temperature, water saturation degree on the thermal conductivity of CPB were gained. It is felt that the present study would contribute to the better optimization of CPB mixtures and the design of more cost-effective and durable CPB underground structures. Keywords. Cemented Paste Backfill; Thermal Conductivity; Hydration; Temperature; Sulphate; Tailings.

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Libros sobre el tema "Cemented paste backfills"

Ahmed, Intisab. Cone penetration test: Application to soil and cemented paste backfills. 2002, 2002.

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Simon, Dragana. Microscale analysis of cemented paste backfill. 2005.

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Roux, Kim-Anne le. In situ properties and liquefaction potential of cemented paste backfill. 2004.

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Capítulos de libros sobre el tema "Cemented paste backfills"

Ghirian, A. y M. Fall. "Properties of Cemented Paste Backfill". En Paste Tailings Management, 59–109. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-39682-8_4.

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Ercikdi, Bayram, Ferdi Cihangir, Ayhan Kesimal y Haci Deveci. "Practical Importance of Tailings for Cemented Paste Backfill". En Paste Tailings Management, 7–32. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-39682-8_2.

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Karaoglu, Kemal y Erol Yilmaz. "Cemented Paste Backfill Pressure Monitoring and Field Testing". En Paste Tailings Management, 195–214. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-39682-8_8.

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Ramlochan, T., M. Grabinsky y R. Hooton. "Microstructural and chemical investigations of cemented paste backfills". En Tailings and Mine Waste '04, 293–304. Taylor & Francis, 2004. http://dx.doi.org/10.1201/9780203021637.ch35.

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Grabinsky, Murray y Mohammadamin Jafari. "Cemented paste backfill response to isotropic compression". En Minefill 2020-2021, 118–26. CRC Press, 2021. http://dx.doi.org/10.1201/9781003205906-12.

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Grabinsky, Murray y Andrew Pan. "Cemented paste backfill failure envelope at low confining stress". En Minefill 2020-2021, 108–17. CRC Press, 2021. http://dx.doi.org/10.1201/9781003205906-11.

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Grabinsky, Murray, Ben Thompson y Will Bawden. "Evaluating cemented paste backfill plug strength and the potential for continuous pouring 1". En Minefill 2020-2021, 127–39. CRC Press, 2021. http://dx.doi.org/10.1201/9781003205906-13.

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Li, Y. G., L. Z. Jin, H. Tan y Y. D. Li. "An experimental study of loading rate effects on mechanical characteristics of cemented paste backfill". En Innovation and Application of Engineering Technology, 129–35. CRC Press, 2017. http://dx.doi.org/10.1201/9781315166599-17.

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Benzaazoua, M., E. Yilmaz, B. Bussière y T. Belem. "Experimental characterization of the influence of curing under stress on the hydromechanical and geochemical properties of cemented paste backfill". En Tailings and Mine Waste '08, 139–52. CRC Press, 2008. http://dx.doi.org/10.1201/9780203882306.ch13.

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Actas de conferencias sobre el tema "Cemented paste backfills"

Belem, Tikou, Andries Fourie y Martin Fahey. "Time-dependent failure criterion for cemented paste backfills". En Thirteenth International Seminar on Paste and Thickened Tailings. Australian Centre for Geomechanics, Perth, 2010. http://dx.doi.org/10.36487/acg_rep/1063_13_belem.

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Thompson, Ben, Tim Hunt, Farid Malek, Murray Grabinsky y William Bawden. "In situ behaviour of cemented hydraulic and paste backfills and the use of instrumentation in optimising efficiency". En Eleventh International Symposium on Mining with Backfill. Australian Centre for Geomechanics, Perth, 2014. http://dx.doi.org/10.36487/acg_rep/1404_27_thompson.

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Zhao, Yue, Li Jie Guo, Abbas Taheri, Murat Karakus y An Deng. "Strain localisation behaviour of cemented paste backfill". En Paste 2021: 24th International Conference on Paste, Thickened and Filtered Tailings. Australian Centre for Geomechanics, Perth, 2021. http://dx.doi.org/10.36487/acg_repo/2115_30.

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Haan, John. "Comparison of cemented paste backfill and cemented rock fill systems". En 14th International Seminar on Paste and Thickened Tailings. Australian Centre for Geomechanics, Perth, 2011. http://dx.doi.org/10.36487/acg_rep/1104_44_haan.

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Helinski, Matthew, Andries Fourie y Martin Fahey. "Mechanics of Early Age Cemented Paste Backfill". En Ninth International Seminar on Paste and Thickened Tailings. Australian Centre for Geomechanics, Perth, 2006. http://dx.doi.org/10.36487/acg_repo/663_27.

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Veenstra, Ryan, Xu Zhao, Andries Fourie y Johannes Grobler. "A comparison of cemented paste backfill shotcrete barricade design methods". En Paste 2021: 24th International Conference on Paste, Thickened and Filtered Tailings. Australian Centre for Geomechanics, Perth, 2021. http://dx.doi.org/10.36487/acg_repo/2115_33.

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Veenstra, Ryan y Johannes Grobler. "Optimising the design stability of cemented paste backfilled stopes". En Paste 2021: 24th International Conference on Paste, Thickened and Filtered Tailings. Australian Centre for Geomechanics, Perth, 2021. http://dx.doi.org/10.36487/acg_repo/2115_37.

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Peng, Xiaopeng, Li Jie Guo, Guangsheng Liu, Xiaocong Yang y C. Wan. "Investigation of inhomogeneous properties of backfill samples to explore a new quantitative criterion for cemented paste backfill identification". En Paste 2021: 24th International Conference on Paste, Thickened and Filtered Tailings. Australian Centre for Geomechanics, Perth, 2021. http://dx.doi.org/10.36487/acg_repo/2115_28.

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Carlier, Chloé y Ryan Veenstra. "The new cemented paste backfill recipes selection method at Newmont Éléonore mine". En Paste 2021: 24th International Conference on Paste, Thickened and Filtered Tailings. Australian Centre for Geomechanics, Perth, 2021. http://dx.doi.org/10.36487/acg_repo/2115_35.

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Grabinsky, Murray, Dragana Simon, Ben Thompson, William Bawden y Ryan Veenstra. "Interpretation of as-placed cemented paste backfill properties from three mines". En Eleventh International Symposium on Mining with Backfill. Australian Centre for Geomechanics, Perth, 2014. http://dx.doi.org/10.36487/acg_rep/1404_28_grabinsky.

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