A Critical State Approach To The Mechanical Behavior Of Early Age Cemented Paste Backfill
DOWNLOAD
Download A Critical State Approach To The Mechanical Behavior Of Early Age Cemented Paste Backfill PDF/ePub or read online books in Mobi eBooks. Click Download or Read Online button to get A Critical State Approach To The Mechanical Behavior Of Early Age Cemented Paste Backfill book now. This website allows unlimited access to, at the time of writing, more than 1.5 million titles, including hundreds of thousands of titles in various foreign languages. If the content not found or just blank you must refresh this page
A Critical State Approach To The Mechanical Behavior Of Early Age Cemented Paste Backfill
DOWNLOAD
Author : Amin B. Ghorbanpour
language : en
Publisher:
Release Date : 2021
A Critical State Approach To The Mechanical Behavior Of Early Age Cemented Paste Backfill written by Amin B. Ghorbanpour and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with Controlled low-strength materials categories.
Early Age Mechanical Behavior And Stiffness Development Of Cemented Paste Backfill With Sand
DOWNLOAD
Author : Abdullah Abdelaal
language : en
Publisher:
Release Date : 2011
Early Age Mechanical Behavior And Stiffness Development Of Cemented Paste Backfill With Sand written by Abdullah Abdelaal and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Early Age Mechanical Behavior And Stiffness Development Of Cemented Paste Backfill With Sand
DOWNLOAD
Author : Abdullah Muhammad Galaa Muhammad Idris Abdelaal
language : en
Publisher:
Release Date : 2011
Early Age Mechanical Behavior And Stiffness Development Of Cemented Paste Backfill With Sand written by Abdullah Muhammad Galaa Muhammad Idris Abdelaal and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
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.
Cemented Paste Backfill
DOWNLOAD
Author : Yong Wang
language : en
Publisher: Elsevier
Release Date : 2024-05-19
Cemented Paste Backfill written by Yong Wang and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024-05-19 with Science categories.
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
Liquefaction Of Early Age Cemented Paste Backfill
DOWNLOAD
Author : Abdolreza Saebimoghaddam
language : en
Publisher:
Release Date : 2010
Liquefaction Of Early Age Cemented Paste Backfill written by Abdolreza Saebimoghaddam and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
Modern mines require systems that quickly deliver backfill to support the rock mass surrounding underground openings. Cemented Paste Backfill (CPB) is one such backfilling method, but concerns have been raised about CPB's liquefaction susceptibility especially when the material has just been placed, and if it is exposed to earthquakes or large mining induced seismic events. Conventional geotechnical earthquake engineering for surface structures is now relatively advanced and well accepted, and so the objective of this thesis is to consider how that framework might be extended to assess the liquefaction potential of CPB. Seismic records were analyzed for earthquakes and for large mining induced events. Important seismological trends were consistent for rockbursts and earthquakes when the signals were recorded at distances as proximate as one kilometre, suggesting that the conventional earthquake engineering approach might plausibly be adapted for such design situations. For production blasts and for more proximate locations to rockbursts, much higher frequencies dominate and therefore new design methods may be required. Monotonic triaxial tests conducted on normally consolidated uncemented mine tailings demonstrated that the material is initially contractive up to a phase transition point, beyond which dilation occurs. Most importantly the material never exhibits unstable strain softening behaviour in compression, and only temporary or limited liquefaction in extension. The addition of 3% binder results in initial sample void ratios that are even higher than their uncemented counterparts, and yet the material friction is slightly enhanced when tested at 4 hours cure. These results suggest that the flow liquefaction phenomenon commonly associate with undrained loose sand fills will not occur with paste backfill. Cyclic triaxial test results analyzed in terms of number of cycles to failure for a given cyclic stress ratio exhibited a trend consistent with previous tests on similar materials. However, the addition of 3% binder and testing at 4 hours cure resulted in an order of magnitude larger number of cycles to failure - a surprising and dramatic increase, suggesting good resistance of the material to cyclic mobility. Future research is recommended to build on these results and develop more robust methods for liquefaction assessment of CPB.
Mechanical Properties Of Cemented Paste Backfill Under Low Confining Stress
DOWNLOAD
Author : Andrew Ning Pan
language : en
Publisher:
Release Date : 2019
Mechanical Properties Of Cemented Paste Backfill Under Low Confining Stress written by Andrew Ning Pan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
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.
Prediction Of Mechanical Performance Of Cemented Paste Backfill By The Electrical Resistivity Measurement
DOWNLOAD
Author : Wenbin Xu
language : en
Publisher:
Release Date : 2018
Prediction Of Mechanical Performance Of Cemented Paste Backfill By The Electrical Resistivity Measurement written by Wenbin Xu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Concrete categories.
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.
Microscale Analysis Of Cemented Paste Backfill Microform
DOWNLOAD
Author : Dragana Simon
language : en
Publisher: Library and Archives Canada = Bibliothèque et Archives Canada
Release Date : 2005
Microscale Analysis Of Cemented Paste Backfill Microform written by Dragana Simon and has been published by Library and Archives Canada = Bibliothèque et Archives Canada this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
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.
Temperature Dependency Of The Rheological Properties And Strength Of Cemented Paste Backfill That Contains Sodium Silicate
DOWNLOAD
Author : Ghada Abdulbaqi Ali
language : en
Publisher:
Release Date : 2021
Temperature Dependency Of The Rheological Properties And Strength Of Cemented Paste Backfill That Contains Sodium Silicate written by Ghada Abdulbaqi Ali and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with categories.
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.
Geotechnical Characterization Of Cemented Paste Backfill
DOWNLOAD
Author : Erol Yilmaz
language : en
Publisher: LAP Lambert Academic Publishing
Release Date : 2015-02-10
Geotechnical Characterization Of Cemented Paste Backfill written by Erol Yilmaz and has been published by LAP Lambert Academic Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-02-10 with categories.
Cemented paste backfill (CPB) technology is now widely utilized by most modern underground hard rock mines in Canada, Australia, the United States, South Africa and Turkey. CPB is a cementitious material produced with three ingredients: filtered wet tailings, hydraulic binders, and mixing water to ensure the paste's flowability in pipeline for final deposition. This book investigates CPB technology using a recently designed lab apparatus called CUAPS (curing under applied pressure system) that estimates in situ CPB conditions. The CUAPS apparatus has been demonstrated as a practical and cost-effective tool that effectively replaces the traditional approach using non-perforated plastic moulds. The results obtained with the CUAPS apparatus will contribute to improve the safety of mines and miners and provide a better understanding of paste backfill. Each section of this book represents an original contribution to the science and engineering of paste backfill. This book provides some theoretical and experimental bases for designing paste backfill mixtures in terms of cost savings and safety and for incorporating in situ backfill behaviour and properties.