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Mechanical Properties Of Cemented Paste Backfill Under Low Confining Stress
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Book Synopsis Mechanical Properties of Cemented Paste Backfill Under Low Confining Stress by : Andrew Ning Pan
Download or read book Mechanical Properties of Cemented Paste Backfill Under Low Confining Stress written by Andrew Ning Pan and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cemented paste backfill (CPB) plays an increasingly important role in the mining industry due to rapid delivery rate, tight-filling characteristics, relatively insignificant water management issues during filling, and generally uniform as-placed mechanical properties. The most common basis for assessing backfill strength is Unconfined Compressive Strength (UCS), and some of the most commonly used design methods have UCS as a fundamental design parameter. However, actual CPB properties and behavior under the range of confining stresses relevant to these design methods has been studied very little. This work uses UCS tests and a novel direct tensile test method and compares test results with strengths obtained from direct shear tests. A form of punching shear was also investigated, but the results were found unsatisfactory for design purposes. For materials with UCS up to about 1 MPa, the UCS and tensile strengths are consistent with the Mohr-Coulomb failure envelope obtained from direct shear tests.
Book Synopsis Cemented Paste Backfill by : Yong Wang
Download or read book Cemented Paste Backfill written by Yong Wang and published by Elsevier. This book was released on 2024-06-03 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: In view of the demand for the research on the transport resistance characteristics and mechanical properties of CPB under the influence of temperature effect, the book comprehensively describes the studies on rheological and mechanical properties of CPB materials used in underground metal mines. This book covers a wide range of topics, including a new definition of CPB, past participation and flow-induced corrosion of pipeline under the constant temperature condition, multiphysics processes in CPB and the associated consolidation process, the variation of rheological parameters and transport resistance, prediction model for rheological properties, mechanical behavior and properties of CPB and fiber-reinforced CPB, and control technology to reduce the adverse effect of temperature. Therefore, an academic framework for the transport resistance characteristics and mechanical properties under the temperature effect was established in this book. Investigates rheological properties and multiphysics processes in CPB materials around the world Looks into systematic studies on pipe transport and mechanical properties of CPB under temperature effects Focuses mainly on the effect of temperature on paste transport and mechanical properties under the temperature effect, which provides a theoretical basis for safe and efficient filling operation and associated future research in this field Offer in-depth insights into the evolution of the rheological and mechanical properties of CPB under the effect of temperatures
Author :Dragana Simon Publisher :Library and Archives Canada = Bibliothèque et Archives Canada ISBN 13 :9780494027202 Total Pages :514 pages Book Rating :4.0/5 (272 download)
Book Synopsis Microscale Analysis of Cemented Paste Backfill [microform] by : Dragana Simon
Download or read book Microscale Analysis of Cemented Paste Backfill [microform] written by Dragana Simon and published by Library and Archives Canada = Bibliothèque et Archives Canada. This book was released on 2005 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study shows that wave-based techniques provide insight into some of the factors that affect the behaviour of CPB. Electromagnetic wave-based measurements are sensitive to changes in structure, free water content, bound water content, and ion availability and/or mobility. This research shows that the effective conductivity is a useful parameter to monitor the hydration process, even in low cement content pastes. Shear wave-based measurements are a useful tool to monitor the stiffness evolution in CPB. Apparent yield stress measurements are sensitive to particle-particle interactions and reflect changes in the material's composition, including water content, binder content and type, and chemical additives. All tests show that during the early stages, Portland cement hydration has little effect on the microstructure development, stiffness and flow characteristics of cement-containing pastes. The macroscopic properties of cemented paste backfill (CPB), including fluidity and strength, depend on particle-particle and particle-fluid interactions; thus, it is important to determine the fundamental interactions between the paste constituents to optimize paste design. Specific topics of interest in this study include the effects of paste composition (e.g., binder content and type, and pore fluid chemistry) on the microstructure development, and electromagnetic, rheological and mechanical properties (e.g., setting time, unconfined compressive strength and stiffness) with time. The effect of the pore fluid chemistry on the properties of the CPB depends on the type and amount of the additive. In CPB, calcium chloride and sodium chloride accelerate cement hydration and improve the UCS during the first six months of hydration. Conversely, ferric chloride and hydrochloric acid retard the hydration and setting of CPB. The tested superplasticizers retard cement hydration, increase the UCS and lower the apparent yield stress of CPB. A drawback to using the superplasticizers tested in this study is that a high shear stress is required to re-initiate flow in the pastes.
Book Synopsis Minefill 2020-2021 by : Ferri Hassani
Download or read book Minefill 2020-2021 written by Ferri Hassani and published by CRC Press. This book was released on 2021-06-02 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series of International Symposiums on Mining with Backfill explores both the theoretical and practical aspects of the application of mine fill, with many case studies from both underground and open-pit mines. Minefill attendees and the Proceedings book audience include mining practitioners, engineering students, operating and regulatory professionals, consultants, academics, researchers, and interested individuals and groups. The papers presented at Minefill symposiums regularly offer the novelties and most modern technical solutions in technology, equipment, and research. In that way, the papers submitted for the Minefill Symposia represent the highest quality and level in the conference domain. For the 2020-2021 edition organizers hope that the papers presented in this publication will also be received with interest by readers around the world, providing inspiration and valuable examples for industry and R&D research.
Book Synopsis Effects of Dynamic Loading on the Geomechanical Behaviour of Cemented Paste Backfill by : Gonzalo Hernan Suazo Fuentealba
Download or read book Effects of Dynamic Loading on the Geomechanical Behaviour of Cemented Paste Backfill written by Gonzalo Hernan Suazo Fuentealba and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: [Truncated] Backfill is any material that is placed underground to fill the voids (stopes) left after the process of extracting minerals from crushed rock. Cemented Paste Backfill (CPB) is one of these materials, which consists of a mixture of full stream tailings, a small percentage of cement and water. Underground space is a dynamic environment that subjects these fills to a series of dynamic loading resulting from blasting and seismic events. Refracted stress waves at the CPB-rock interface can increase the shear and compressive stresses in the fill. As a result, excess pore water pressures may develop and liquefaction can eventually be triggered. Liquefaction might cause the failure of the retaining barricade constructed at the bottom of the stope since total pressure can rise to as high as the full hydrostatic head of the fill. However, the amount of dynamic energy transmitted to the fill as well as the liquefaction risk, greatly diminishes as the fill desaturates and negative water pressures arise in the pore space. In this context, the primarily objective of this thesis is to evaluate the liquefaction susceptibility of CPB at early curing ages due to seismic and blasting stress waves. In addition, the propagation phenomena of compressional waves in CPB, the effects of degree of saturation on stress wave refraction at CPB interfaces and the blast response of a backfilled stopes are explored. Finally, the evolution of unsaturated CPB properties and the mechanism of desaturation of the fill are investigated. This research consisted of in situ and experimental testing, and a numerical modelling component.Direct simple shear (DSS) tests were conducted to study the cyclic undrained shear response of CPB. The effects of confining stress, initial static shear stress and void ratio on the liquefaction resistance of uncemented fine-grained tailings was firstly researched. Then, the cyclic response of cemented tailings prepared at different curing ages, cement contents and initial void ratios, was examined. The material, independently of the degree of cementation, showed a predominantly cyclic mobility type response with large degradation of shear stiffness at advanced numbers of shear cycles. However, no flow type of failure was observed in any of the tests conducted. The overburden stress correction factor was found to decrease with increasing confining stresses in the range 100 to 400 kPa and to gradually increase from 400 kPa onwards, when samples were tested at the same initial void ratio. Similarly, higher cement contents, longer curing periods or higher initial solids contents were found to increase liquefaction resistance. A unconfined compressive strength (UCS) of about 70kPa, which corresponds to a shear wave velocity of 220 m/s, was found to be adequate to resist liquefaction under a large earthquake-induced cyclic stress ratio (CSR).
Book Synopsis Paste Tailings Management by : Erol Yilmaz
Download or read book Paste Tailings Management written by Erol Yilmaz and published by Springer. This book was released on 2017-03-03 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an overview of paste tailings disposal at mine sites. It deals comprehensively with the characterization of sulphide-rich tailings, geotechnical and microstructural behaviour, surface tailings disposal applications, underground paste backfilling, and case studies. The authors place emphasis on the characterization, monitoring, disposal and treatment, as well as environmental considerations of problematic sulphidic tailings. The framework is supported by worldwide case studies.
Book Synopsis Strength and Deformation Behaviour of Cemented Paste Backfill in Sub-zero Environment by : Shuang Chang
Download or read book Strength and Deformation Behaviour of Cemented Paste Backfill in Sub-zero Environment written by Shuang Chang and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Deep Rock Mechanics: From Research to Engineering by : Heping Xie
Download or read book Deep Rock Mechanics: From Research to Engineering written by Heping Xie and published by CRC Press. This book was released on 2018-12-19 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: At present, deep earth resources remain poorly understood and entirely under-utilised. There is a growing appreciation of the important role deep earth will play in future sustainability, particularly in opportunities for new and sustainable large-scale energy alternatives, and extraction of resources through mining and greenhouse mitigation. Deep Rock Mechanics: From Research to Engineering is a collection of papers on the effective development of deep earth resources, which were presented at the International Conference on Geo-mechanics, Geo-Energy and Geo-Resources 2018 (Chengdu, P.R. China, 22-24 September 2018). The contributions aim at breaking beyond existing patterns of discovery, to advance research on geomechanical and geophysical processes in deep earth resources and energy development, enhancing deep earth energy and mineral extraction and mitigating harmful atmospheric emissions. Deep Rock Mechanics: From Research to Engineering covers a wide range of topics: 1. Deep rock mechanics and mining theory 2. Water resources development and protection 3. Unconventional oil and gas extractions 4. CO2 sequestrations technologies and nuclear waste disposal 5. Geothermal energy 6. Mining engineering 7. Petroleum engineering 8. Geo-environmental engineering 9. Civil geotechnical engineering Deep Rock Mechanics: From Research to Engineering promotes safer and greener ways for energy and resource production at great depth, and will serve as a must-have reference for academics and professionals involved or interested in geo-mechanics, geo-energy, and geo-resources.
Book Synopsis Minefill 2020-2021 by : Ferri Hassani
Download or read book Minefill 2020-2021 written by Ferri Hassani and published by CRC Press. This book was released on 2021-06-02 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series of International Symposiums on Mining with Backfill explores both the theoretical and practical aspects of the application of mine fill, with many case studies from both underground and open-pit mines. Minefill attendees and the Proceedings book audience include mining practitioners, engineering students, operating and regulatory professionals, consultants, academics, researchers, and interested individuals and groups. The papers presented at Minefill symposiums regularly offer the novelties and most modern technical solutions in technology, equipment, and research. In that way, the papers submitted for the Minefill Symposia represent the highest quality and level in the conference domain. For the 2020-2021 edition organizers hope that the papers presented in this publication will also be received with interest by readers around the world, providing inspiration and valuable examples for industry and R&D research.
Book Synopsis Prediction of Mechanical Performance of Cemented Paste Backfill by the Electrical Resistivity Measurement by : Wenbin Xu
Download or read book Prediction of Mechanical Performance of Cemented Paste Backfill by the Electrical Resistivity Measurement written by Wenbin Xu and published by . This book was released on 2018 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cemented Paste Backfill (CPB) has become a useful practice in many modern operations around the world. This method is an innovative tailings disposal and underground mine backfilling scheme that returns much of this material to the underground stope field. Thus, it is of great interest for financial and security reasons to fully comprehend the mechanical performance of such underground CPB. Uniaxial compressive strength (UCS) is one of the most commonly used parameters for evaluating the mechanical performance of CPB. Electrical resistivity (ER) measurement, which is a method of nondestructive testing, can also be used to determine the mechanical properties of CPB. This study was undertaken to suggest a nondestructive testing method that would permit prediction of the UCS of a CPB within 90 days. Five CPB samples were prepared at different cement-to-tailing ratios (1/4, 1/6, and 1/8 by weight) and solid content (65 and 70 wt. %), and a curing period of 3-90 days was used for ER measurement. Seventy-five CPB samples were prepared with the same cement content as those used in the pastes for UCS tests cured for 3, 7, 28, 56, and 90 days. The results of the ER measurement show that the ER versus curing periods of 3-90 days first drop to a minimum value and then gradually increase with time. The greater ER values of CPB are reached when the greater cement-to-tailing ratio and solid content is used. A logarithmic relationship is established between the UCS and the ER of CPB at 90 days. It is possible that a nondestructive method could be developed to evaluate the strength of underground CPB based on the obtained logarithmic relationship with ER at 90 days.
Book Synopsis Effects of Transient Hydro-mechanical Cemented Paste Tailings Properties on One-dimensional Deposition Behaviour by : Mohammad Shahsavari Goughari
Download or read book Effects of Transient Hydro-mechanical Cemented Paste Tailings Properties on One-dimensional Deposition Behaviour written by Mohammad Shahsavari Goughari and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: When underground mining voids are filled with Cemented Paste Backfill (CPB) a dynamic interaction occurs between the hydrating CPB's engineering properties (hydraulic conductivity, stiffness and strength) and the fill rise rate, drainage conditions, and underground atmospheric conditions. These interactions are particularly important in the first 24 hours after a fill layer's placement in order to support continuous filling. Unfortunately, most previous studies started taking measurements at one day or more, missing this critical initial period. The work presented in this thesis obtains representative material properties at curing times as soon as 30 minutes. Four stages of hydraulic conductivity evolution are linked to corresponding stages of binder hydration at times from 30 minutes to 5 days, and it is shown conventional measurement methods could under-estimate initial hydraulic conductivity by an order of magnitude. Consolidation tests with virtually continuous loading rates simulated effective stress development onsets between 4 and 48 hours, at rates between 5 and 20 kPa/hr and final level of 400 kPa. In virtually continuous loading it is impossible to deconvolve the parameters controlling the ultimately achieved void ratio and stiffness, but a graphical technique is developed to aid preliminary design and determine likely void ratios that should be used in other laboratory tests for engineering properties. The hydraulic conductivity and consolidation element test results are then used to interpret results from four mesoscale laboratory experiments that simulate continuous backfilling. These tests demonstrate the importance of properly simulating the underground atmospheric conditions, and in placing the fill in the most continuous manner possible. For placement conditions that most closely simulate the actual placement conditions at the studied mine, it is found that virtually no self-weight consolidation occurs and thus the void ratios in the field and in the meso-scale experiments are essentially identical. Therefore, the effective stress path realized in the field will not lead to significant self-weight consolidation and the attendant strength gains that might otherwise occur.
Book Synopsis Temperature Dependency of the Rheological Properties and Strength of Cemented Paste Backfill That Contains Sodium Silicate by : Ghada Abdulbaqi Ali
Download or read book Temperature Dependency of the Rheological Properties and Strength of Cemented Paste Backfill That Contains Sodium Silicate written by Ghada Abdulbaqi Ali and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decades, cemented paste backfill (CPB) has become a common, environmentally friendly method of managing mine wastes (such as tailings). This technology allows up to 60% of the total amount of tailings to be reused and filled in the mine stopes after converting them into cemented material. Beside reducing the environmental risks associated with the traditional disposal of these materials, turning them into cemented material and placing them in the underground mine stopes can also provide secondary support for these stopes in addition to minimizing the risk of ground subsidence in the mine area. CPB is an engineered mixture of tailings, water, and hydraulic binder (such as cement, blast furnace slag, and fly ash) that is mixed in the paste plant and delivered into the mine stopes through a gravity or pumping based transportation system. During the transportation of CPB through the delivery system pipelines, the flowability of CPB depends on the rheology of the transported CPB, which is affected by different factors, such as the transportation time, temperature variation, binder type, and chemical composition of these mixtures. In addition, the performance of CPB, after placing the CPB mixture into the mine stopes, is mainly dependent on the role of the hydraulic binder, as it increases the mechanical strength of the mixture through the process of cement hydration. The mechanical strength is also influenced by different factors, such as time progress, temperature variation, and presence of chemical additives. It has previously been found that fresh CPB transported and/or placed in the mine stopes can be susceptible to temperature variation of different sources, such as the climatic effects, heat generated from the surrounding rocks, and heat generated during the process of cement hydration. Unsuitable flowability of CPB through the delivery system might lead to significant financial losses due to clogging of pipelines with unexpected hardening of CPB during transportation, which will cause delay in work and possible damages to the pipelines. Also, failure of CPB structure in the mine stopes due to inappropriate mechanical strength may cause casualties to the mine workers as well as significant environmental and economic damages. Many researchers studied the rheological properties and/or strength development of CPB under the individual effect of any of the aforementioned factors. Additionally, many researchers have evaluated the coupled effect of some of these factors on the rheology and mechanical strength of CPB material. Hitherto, there are currently no studies that addressed the combined effect of all these conditions on the rheological properties and strength development of CPB. At the first stage of this M.A.Sc. study, a series of experimental tests was conducted on fresh CPB in order to determine the combined effect of time, temperature, binder content, and chemical additives on the rheological properties of CPB. These experiments include rheological properties test (yield stress and viscosity), microstructural analysis (thermal analysis and XRD), chemical analysis (pH and Zeta potential), and monitoring tests (electrical conductivity), which were conducted on 125 CPB samples that were mixed and prepared at different temperatures (2oC, 20oC, 35oC) and cured for different curing time (0 hrs., 0.25 hrs., 1 hr., 2hrs, and 4 hrs.). These samples were prepared with different blends of hydraulic binders (PCI, PCI/Slag, and PCI/FA) and contained different dosages of sodium silicate (0%, 0.1%, 0.3%, and 0.5%). The results obtained show that rheology of CPB increases with the progress of curing time. It also increases with the increase in the initial (mixing and curing) temperature and content of sodium silicate. It was also found that the partial usage of slag and FA reduces the rheological properties. However, CPBs containing PCI/FA as binder have lower rheological properties, and thus better flowability, than those that contain PCI/Slag as binder. At the second stage of this M.A.Sc. study, in order to understand the combined effect of time, temperature and sodium silicate content on the strength development of slag-CPB, unconfined compression (UCS) test, microstructural analysis (thermal analysis and MIP), and monitoring tests (electrical conductivity, suction, and volumetric water content) were conducted on 72 CPB samples that were prepared with PCI-Slag as a binder, cured for different times (1 day, 3 days, 7 days, and 28 days) under different curing temperatures of (2oC, 20oC, 35oC), and contained different dosages of sodium silicate (0%, 0.3% and 0.5%). The results obtained at this stage showed that the strength development of slag-CPB increases with the progress of curing time and temperature. It also increases with the increase in the sodium silicate content. Also, the combined effect of high temperature, high dosage of sodium silicate and longer curing time showed significant enhancement in the mechanical strength of slag-CPB. The findings of this M.A.Sc. research will contribute to cost effective, efficient, and safer design of CPB structures in the mine areas. It will also help in minimizing financial loss associated with unsuitable flowability of CPB transported in the CPB delivery system besides reducing the risks of human loss, and the environmental and economic damages associated with the failure of CPB structures.
Author :Kim-Anne Le Roux Publisher :National Library of Canada = Bibliothèque nationale du Canada ISBN 13 :9780612918634 Total Pages :542 pages Book Rating :4.9/5 (186 download)
Book Synopsis In Situ Properties and Liquefaction Potential of Cemented Paste Backfill [microform] by : Kim-Anne Le Roux
Download or read book In Situ Properties and Liquefaction Potential of Cemented Paste Backfill [microform] written by Kim-Anne Le Roux and published by National Library of Canada = Bibliothèque nationale du Canada. This book was released on 2004 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury intrusion porosimetry as well as semi-qualitative image analysis techniques such as scanning electron microscopy, microCT and visual analysis software were used to develop an understanding of the structure developed in field CPB in both the macro and micro scale. Standard oedometer consolidation testing with a modified loading rate was used to investigate the interrelationship of loading rate, which simulates rate of paste accumulation in a stope and the hydration of binder of the paste. The results show that the structure that develops is sensitive to both the binder content of the CPB and the rate of paste accumulation. Cemented paste backfill (CPB) has gained increasing popularity in the last 5 to 10 years and is used routinely in several mines. However, most of the CPB designs are based on laboratory prepared CPB material properties and there is growing awareness that the field CPB may be different from the laboratory prepared material. A field based investigation quantified the extent to which the field material differs from laboratory material. Not only is the field material more heterogeneous than expected, but on average it has a higher void ratio and a lower degree of saturation. These differences impact the performance of the field material. Numerical analysis using FLAC 3D was undertaken to show the influence of the field condition on the stability of the CPB. This research provides practical recommendations for industrial application and provides a framework for further investigation of CPB. Several research projects arising from this initial work are already underway through the Lassonde Institute at the University of Toronto, and several more are at the proposal stage. Static and dynamic liquefaction testing of early age CPB showed that liquefaction due to self-weight alone is unlikely but that blasting too close to the CPB can mobilize the material. Practical recommendations such as limiting blasting in proximity to early age CPB and cordoning off vulnerable areas during the critical initial 24 hr period that the paste is vulnerable to dynamic liquefaction. The cyclic liquefaction results are believed to be the first reported for cemented paste backfill.
Book Synopsis Mechanical Properties of Cement-treated Soils in Relation to Their Use in Embankment Construction by : Mohamed Moustapha Abboud
Download or read book Mechanical Properties of Cement-treated Soils in Relation to Their Use in Embankment Construction written by Mohamed Moustapha Abboud and published by . This book was released on 1973 with total page 592 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Strength and Environmental Properties of Cemented Paste Backfill That Contains Sodium Silicate by : Hoda Mohammad Pour
Download or read book Strength and Environmental Properties of Cemented Paste Backfill That Contains Sodium Silicate written by Hoda Mohammad Pour and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Gas-water-rock interaction and multi physical field coupling mechanism by : Leilei Si
Download or read book Gas-water-rock interaction and multi physical field coupling mechanism written by Leilei Si and published by Frontiers Media SA. This book was released on 2023-05-11 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Early Age Mechanical Behavior and Stiffness Development of Cemented Paste Backfill with Sand by : Abdullah Muhammad Galaa Muhammad Idris Abdelaal
Download or read book Early Age Mechanical Behavior and Stiffness Development of Cemented Paste Backfill with Sand written by Abdullah Muhammad Galaa Muhammad Idris Abdelaal and published by . This book was released on 2011 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rapid delivery of backfill to support underground openings attracted many mines to adopt paste backfilling methods. As a precaution to prevent liquefaction and to improve the mechanical performance of backfills, a small portion of a binder is added to the paste to form the cemented paste backfill (CPB). Recently, adding sand to mine tailings (MT) in CPB mixes has attracted attention since it enhances the flow and mechanical characteristics of the pastefill. This thesis investigates the effects of adding sand to CPB on the undrained mechanical behavior of the mixture (CPBS) under monotonic and cyclic loads. Liquefaction investigations took place at the earliest practically possible age. Beyond this age, the present research focused on characterizing the evolution of stiffness and obtaining the values of the stiffness parameters that could be useful for designing and modeling backfilling systems.The evolution of effective stiffness parameters for two CPB-sand mixtures was monitored in a non-destructive triaxial test for five days. Self-desiccation was found to not be influential on the development of early age stiffness. Moreover, a framework is suggested to predict the undrained stiffness at degrees of saturation representative of the field. The credibility of the proposed test in providing stiffness parameters at representative strain levels of the field was verified.The liquefaction investigation involved monotonic compression and extension triaxial tests. Neither flow nor temporary liquefaction was observed for all cemented and uncemented specimens under monotonic compression, while temporary liquefaction was observed for all specimens under monotonic extension. The addition of binder and sand to MT was found to slightly strengthen the pastefill in compression while weakening it in extension. Under cyclic loading, the addition of sand negatively impacted the cyclic resistance. However, binder was found to be more effective in the presence of sand. All specimens exhibited a cyclic mobility type of response.
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