Assessment Of The Modified Cuaps Apparatus To Estimate In Situ Properties Of Cemented Paste Backfill
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Assessment Of The Modified Cuaps Apparatus To Estimate In Situ Properties Of Cemented Paste Backfill
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Author : Erol Yilmaz
language : en
Publisher:
Release Date : 2010
Assessment Of The Modified Cuaps Apparatus To Estimate In Situ Properties Of Cemented Paste Backfill written by Erol Yilmaz and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Compressive strength categories.
This paper evaluates some improvements in the design of a laboratory apparatus called curing under applied pressure system (CUAPS) designed to estimate in situ properties of cemented paste backfill (CPB). This apparatus is effective in conducting the following tests on samples during curing: (i) One-dimensional consolidation test with or without pore water pressure (PWP) measurement, (ii) PWP dissipation test, (iii) saturated hydraulic conductivity (permeability) test, and (iv) curing under constant or variable vertical pressure. Unconfined compression tests can be also performed on consolidated CPB samples after each of these tests. The modified CUAPS apparatus is assessed in this paper. Preliminary results are promising and validate the functionality of the CUAPS apparatus, which will contribute to the knowledge on consolidation behaviour of in situ CPB material.
Non Bf Slag Based Green Cementitious Materials
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Author : Lijie Guo
language : en
Publisher: Frontiers Media SA
Release Date : 2022-08-12
Non Bf Slag Based Green Cementitious Materials written by Lijie Guo and has been published by Frontiers Media SA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-08-12 with Technology & Engineering categories.
Managing Mining And Minerals Processing Wastes
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Author : Chongchong Qi
language : en
Publisher: Elsevier
Release Date : 2023-03-10
Managing Mining And Minerals Processing Wastes written by Chongchong Qi and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-03-10 with Science categories.
Managing Mining and Minerals Processing Wastes: Concepts, Design and Applications presents fundamental knowledge in waste management in mining and minerals processing and summarizes recent advances. The book offers readers insights into innovative ways to manage waste in the mining and minerals industry. Sections cover a brief introduction to this topic and an explanation of waste generation, and how to manage the six types of waste, including waste rock, mill tailings, coal refuse and coal fly ash, quarry waste, metallurgical slugs and washery rejects. The title then emphasizes the management of hazardous waste, the acid mine drainage and the lifecycle assessment of waste management. Finally, the book considers current and emerging challenges. This publication offers a comprehensive background to waste management in mining and minerals processing and a summary of recent advances and innovative strategies for managing each kind of waste. - Presents the background to waste management in minerals and mining, also summarizing recent advances - Provides an accessible introduction to the current state of, and future prospects for, waste management - Helps readers increase their usable knowledge on waste management in mining and minerals engineering - Offers new insights into how waste can be managed in innovative ways - Covers hazardous waste, acid mine drainage, lifecycle assessment and emerging issues
In Situ Properties And Liquefaction Potential Of Cemented Paste Backfill Microform
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Author : Kim-Anne Le Roux
language : en
Publisher: National Library of Canada = Bibliothèque nationale du Canada
Release Date : 2004
In Situ Properties And Liquefaction Potential Of Cemented Paste Backfill Microform written by Kim-Anne Le Roux and has been published by National Library of Canada = Bibliothèque nationale du Canada this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.
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.
Investigating The Hydrogeotechnical And Microstructural Properties Of Cemented Paste Backfill Using The Cuaps Apparatus
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Author : Erol Yilmaz
language : en
Publisher:
Release Date : 2013
Investigating The Hydrogeotechnical And Microstructural Properties Of Cemented Paste Backfill Using The Cuaps Apparatus written by Erol Yilmaz and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Microscale Analysis Of Cemented Paste Backfill Microform
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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.
An Experimental Study Of Cementing Paste Backfill
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Author : Megan Walske
language : en
Publisher:
Release Date : 2014
An Experimental Study Of Cementing Paste Backfill written by Megan Walske and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
[Truncated abstract] This thesis focuses on experimental element testing of cementing paste backfill (CPB) to examine and improve on existing laboratory testing techniques. Specifically, the work focuses on developing a framework to account for differences in curing conditions between in situ and laboratory environments, given the recognised improvement in mechanical properties of in situ cured CPB. This has been explored within the effective stress framework by making use of a hydration cell testing apparatus. The existing hydration cell set-up was modified to allow control over the rate of temperature increase and final temperature of specimens during curing, to replicate in situ curing conditions. The combination of elevated curing temperature and effective stress generation was found to significantly increase the mechanical properties of CPB compared with curing at elevated effective stress and ambient temperatures. The current procedure for curing under effective stress can be expensive and time consuming. As such, the standard test method for chemical shrinkage of hydraulic cement paste (ASTM C1608-07) was investigated as a potential index/screening test for use in the design of CPB mixes through comparison of the chemical shrinkage-induced strain generated in both the ASTM and hydration cell tests. The appropriate use of this ASTM standard with CPB was validated despite the high w/c ratio of typical CPB mixes.
Temperature Dependency Of The Rheological Properties And Strength Of Cemented Paste Backfill That Contains Sodium Silicate
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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.
Mechanical Properties Of Cemented Paste Backfill Under Low Confining Stress
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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.
Using Thermal Profiles Of Cemented Paste Backfill To Predict Strength
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Author : Mahsa Mozaffaridana
language : en
Publisher:
Release Date : 2011
Using Thermal Profiles Of Cemented Paste Backfill To Predict Strength written by Mahsa Mozaffaridana 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.
Measurement of the strength development of Cemented Paste Backfill in laboratory cast cylinders does not replicate the in situ strengths of CPB in mine stopes. The mass of CPB in a filled stope is large and temperature rises due to the heat of hydration of the cementing materials, thus accelerating the gain in strength, relative to laboratory specimens stored at ambient temperature. The purpose of this study was to determine the impact on strength development when CPB test cylinders were subjected to a temperature profile mimicking that in a large mass, such as a mine stope. Also, maturity (the integral of time and temperature during hydration of the CPB) was compared to actual strengths, and the maturity -- strength concept used in concrete technology was applied. It was found that the strength- maturity relationship was applicable to CPB once the base line or datum temperature was adjusted.