scholarly journals Shear Properties of Cemented Paste Backfill under Low Confining Stress

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Andrew N. Pan ◽  
Murray W. F. Grabinsky ◽  
Lijie Guo
Keyword(s):  
Shear Strength ◽  
Mining Industry ◽  
Binder Content ◽  
Environmental Benefits ◽  
Direct Shear ◽  
Cemented Paste Backfill ◽  
Curing Time ◽  
Confining Stress ◽  
Strain Property ◽  
Paste Backfill

Cemented paste backfill (CPB) plays an important role in the mining industry due to safety, cost efficiency, and environmental benefits. Studies on CPB have improved the design and application of paste backfill in underground mines. Direct shear is one of the most fundamental parameters for assessing backfill strength. This study harnesses direct shear tests to explore the low confining stress behavior of CPB. We perform all the tests in a standard apparatus on the combination of three binder contents of 4.2%, 6.9%, and 9.7% CPB with four curing times of 3, 7, 14, and 28 days, respectively. The applied confining stress levels vary in a range according to the in situ regime. Results are presented by strength envelope, stress-strain property, and shear strength with curing time and binder content. The data suggest that the shear strength follows the Mohr–Coulomb envelope in which the shear strength and behavior are time and binder content dependent. In addition, the results show that shear strength is strongly related to the binder content than the curing time, namely, the higher the degree of binder hydration, the higher the cementation binding force between CPBs.

Shear Strength of a Cemented Paste Backfill Submitted to High Confining Pressure

2016 ◽  
Vol 858 ◽  
pp. 219-224 ◽  
Author(s):  
Eduardo Eiler Batista de Araújo ◽  
Dragana Simon ◽  
Fagner Alexandre Nunes de França ◽  
Osvaldo de Freitas Neto ◽  
Olavo Francisco dos Santos Jr.
Keyword(s):  
Shear Strength ◽  
Triaxial Compression ◽  
Binder Content ◽  
Cemented Paste Backfill ◽  
Compression Tests ◽  
Mining Operations ◽  
Geomechanical Properties ◽  
Confining Pressures ◽  
Paste Backfill ◽  
Curing Method

Deep mining operations require special measures in order to keep safe and economic aspects. After mine ore is extracted, voids are created and need to be filled with high-strength, low-cost materials. Cemented Paste Backfill (CPB) has recently become one of the main alternatives in filling stopes. Although numerous papers have mentioned the magnitudes of the strength of this material, its behavior under high confining pressures is still not well understood. Therefore, the purpose of this study is to increase the knowledge regarding the CPB behavior. Triaxial compression tests were performed using a Hoek Cell and Load Frame System under high confining pressures. Samples with two different binder contents were used in order to obtain the CPB strength improvement. Besides the self-weight consolidation curing method, samples were subjected to a different curing method that simulated a zero gravity condition (rotating wheel) in the first curing day to compare their mixture properties. The results suggested that both curing method and binder content have influenced the geomechanical properties of Cemented Paste Backfill. By increasing the curing time, the CPB shear strength has increased slightly, whereas specimens with higher binder content presented a significant increase in shear strength values.

scholarly journals Mechanical Characteristics and Stress Evolution of Cemented Paste Backfill: Effect of Curing Time, Solid Content, and Binder Content

2022 ◽  
Vol 8 ◽  
Author(s):  
Chen Hou ◽  
Liujun Yang ◽  
Lei Li ◽  
Baoxu Yan
Keyword(s):  
Mechanical Properties ◽  
Mechanical Characteristics ◽  
Peak Stress ◽  
Solid Content ◽  
Binder Content ◽  
Cemented Paste Backfill ◽  
Curing Time ◽  
Stress Evolution ◽  
Stress Strain ◽  
Paste Backfill

The clarification of the variation on the strength of the cemented paste backfill (CPB) under the coupling of multi-factor is the foundation of the CPB design of the mine. In this article, the physical and mechanical properties of the CPB under the coupling effect of curing time, solid content, and binder content were experimentally and theoretically investigated. The results show that 1) the increase in binder content can effectively increase the later strength of CPB. 2) A sensitivity parameter considering the span of multi-factor was constructed, indicating that the curing time has the greatest impact on the uniaxial compressive strength (UCS), and the variation in solid content has the least impact on it, which can be verified by the stress–strain curves. 3) Curing time and binder content can effectively change the stress evolution, which is reflected in reducing the strain corresponding to the peak stress, enhancing the characteristics of the peak stress and increasing stress drop. The results of this study aim to explain the essence of the influence of each factor on the mechanical behavior of CPB in the view of stress–strain evolution, which will help to better understand the mechanical characteristics of CPB and quantify the sensitivity of the mechanical properties to various factors.

Effects of curing time and ice-to-water ratio on performance of cemented paste backfill containing ice slag

2019 ◽  
Vol 228 ◽  
pp. 116639 ◽  
Author(s):  
Lang Liu ◽  
Chao Zhu ◽  
Chongchong Qi ◽  
Mei Wang ◽  
Chao Huan ◽  
...  
Keyword(s):  
Cemented Paste Backfill ◽  
Curing Time ◽  
Paste Backfill ◽  
Water Ratio

Fluidity and Mechanical Behavior of Cement Solidified Lead-Zinc Mine Tailings

2014 ◽  
Vol 898 ◽  
pp. 383-386 ◽  
Author(s):  
Chun Lei Zhang ◽  
Shun Cai Wang ◽  
Fan Lu Min
Keyword(s):  
Mine Tailings ◽  
Cement Content ◽  
Strength Increase ◽  
Cemented Paste Backfill ◽  
Curing Time ◽  
Test Results ◽  
The World ◽  
Paste Backfill ◽  
Lead Zinc ◽  
Zinc Mine

Cemented paste backfill method has been widely used in many modern mines throughout the world due to the increasingly stringent environmental regulations and short of disposal land. This study presents experimental results on the use of Portland cement in the solidification of Pb-Zn tailings in China. Test results show UCS strength increase lineally with cement content, tailings concentration, and curing time, respectively. There exist a minimum cement content and tailings concentration to produce obvious strength. The fluidity decrease quickly with cement proportion and tailings concentration, under the satisfying of a minimum pumping fluidity, the increase of tailings concentration can effectively reduce the cement consumption so as to decrease the treatment cost.

scholarly journals Predicting the Isotropic Volumetric Compression Response of Hydrating Cemented Paste Backfill (CPB)

2021 ◽  
Author(s):  
mohammadamin jafari ◽  
Murray Grabinsky
Keyword(s):  
High Stress ◽  
Binder Content ◽  
Cemented Paste Backfill ◽  
Compression Tests ◽  
Isotropic Compression ◽  
Initial Yield Stress ◽  
Laboratory Test Results ◽  
Cure Time ◽  
Paste Backfill ◽  
Compression Line

Abstract Deep and high-stress mining results in stress transfers onto the previously placed backfill, and mines have recorded several MPa induced backfill stress. Understanding the backfill-rock mass interaction is therefore critical. Previous work considered tabular ore bodies undergoing primarily one-dimensional compression and showed how the backfill reaction curves could be estimated from oedometer laboratory test results. This work considers massive orebodies and develops a similar approach based on isotropic compression curves. Isotropic compression tests exceeding 6 MPa are carried out on samples with 3.0–11.1% binder content, tested at 1-day cure time to 28-day cure time. The compression curve is characterized in three stages: initial elastic compression up to a yield point, followed by a transition stage to the start of a final stage with a linear post-yield compression line in \({\epsilon }_{v}-\text{l}\text{o}\text{g}\left({p}^{\text{'}}\right)\) space. Because these isotropic compression tests are rare (the reported results are the first for Cemented Paste Backfill), attempts are made to relate the isotropic compression test parameters to parameters from the more commonly used Unconfined Compression Strength (UCS) tests. Unifying equations as functions of binder content and cure time are found to determine the initial yield stress and the peak strength from UCS tests. These are then related to the corresponding parameters in isotropic compression. Finally, the slope of the post-yield compression line is found as a function of UCS, thereby enabling complete reconstruction of the isotropic compression response based on parameters from carefully controlled UCS tests, as functions of binder content and cure time. Although the calibrated parameters are specific to the studied mine’s materials, the framework is general and applicable to other mines’ CPBs.

scholarly journals Insight into Saturated Hydraulic Conductivity of Cemented Paste Backfill Containing Polycarboxylate Ether-Based Superplasticizer

Minerals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 93
Author(s):  
Sada Haruna ◽  
Mamadou Fall
Keyword(s):  
Hydraulic Conductivity ◽  
Environmental Performance ◽  
Mining Industry ◽  
Design Criterion ◽  
Saturated Hydraulic Conductivity ◽  
Curing Temperature ◽  
Partial Replacement ◽  
Cemented Paste Backfill ◽  
Curing Conditions ◽  
Paste Backfill

Recycling of tailings in the form of cemented paste backfill (CPB) is a widely adopted practice in the mining industry. Environmental performance is an important design criterion of CPB structures. This environmental performance of CPB is strongly influenced by its saturated hydraulic conductivity (permeability). Superplasticizers are usually added to improve flowability, but there is a limited understanding of their influence on the hydraulic properties of the CPB. This paper presents new experimental results on the variations of the hydraulic conductivity of CPB containing polycarboxylate-based superplasticizer with different compositions and curing conditions. It is found that the hydraulic conductivity of the CPB decreases with the addition of superplasticizer, which is beneficial to its environmental performance. The reduction is largely attributable to the influence of the ether-based superplasticizer on particles mobility and cement hydration. Moreover, both curing temperature and time have correlations with the hydraulic conductivity of CPB containing superplasticizer. In addition, the presence of sulfate and partial replacement of PCI with blast furnace slag reduces the hydraulic conductivity. The variations are mainly due to the changes in the pore structure of the CPB. The new results discussed in this manuscript will contribute to the design of more environmental-friendly CPBs, which is essential for sustainable mining.

In situ measurements of cemented paste backfill at the Cayeli Mine

2012 ◽  
Vol 49 (7) ◽  
pp. 755-772 ◽  
Author(s):  
B.D. Thompson ◽  
W.F. Bawden ◽  
M.W. Grabinsky
Keyword(s):  
Cement Hydration ◽  
Time Pressure ◽  
Binder Content ◽  
Underground Mines ◽  
Cemented Paste Backfill ◽  
In Situ Data ◽  
Field Instrumentation ◽  
Rise Rate ◽  
Paste Backfill

Cemented paste backfill (CPB) is accepted as the optimal backfilling material for many underground mines. However, the lack of in-stope backfill pressure data poses fundamental problems from both operational and research standpoints. In response to the requirement for in situ data, a comprehensive field instrumentation project has been conducted. Results are presented here for two stopes at the Cayeli Mine, where geotechnical instruments were installed at the barricades and throughout the stopes. Measurements from a large (slow rise rate) stope with high binder content CPB demonstrated a rapid departure from hydrostatic loading, resulting in relatively low barricade pressures. Conversely, data from a smaller (fast rise rate) stope with lower binder content CPB demonstrated that when cement hydration is retarded, high barricade pressures occur. These examples illustrate the relationship between CPB rise rate and the moderating effect of cement hydration on in situ pressures, which ultimately control barricade pressures. Once CPB gains shear strength, arching of pressures occurs. In situ pressures were reduced with proximity to stope walls and further, under stope access brows, demonstrating that barricade location influences barricade loads. The application of real-time pressure monitoring of pastefill barricades has been demonstrated as an important tool in optimizing operational backfilling efficiency.

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