Yield stress of cemented paste backfill in sub-zero environments: Experimental results

2016 ◽  
Vol 92 ◽  
pp. 141-150 ◽  
Author(s):  
Jiang Haiqiang ◽  
Mamadou Fall ◽  
Liang Cui
Keyword(s):  
Yield Stress ◽  
Experimental Results ◽  
Cemented Paste Backfill ◽  
Paste Backfill

scholarly journals Investigating the Effect of Solid Components on Yield Stress for Cemented Paste Backfill via Uniform Design

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Yong Wang ◽  
Aixiang Wu ◽  
Lianfu Zhang ◽  
Fei Jin ◽  
Xiaohui Liu
Keyword(s):  
Yield Stress ◽  
Mass Fraction ◽  
Cement Content ◽  
Uniform Design ◽  
Free Water ◽  
Experimental Program ◽  
Cemented Paste Backfill ◽  
Free Water Content ◽  
Key Factor ◽  
Paste Backfill

Cemented paste backfill (CPB) technology has been applied quite popular around the world. Yield stress is a key factor determining whether CPB could be transported. In order to reveal the effect of solid components on yield stress of CPB, a uniform design experimental program (four factors and six levels) was conducted to test the rheological property of a mine’s CPB. The tested four factors including mass fraction, cement versus other solids ratio, coarse tailings, and gravel contents were considered during the experiment design. Likewise, six experimental levels were given to each factor. Results of the test show that yield stress increased with the mass fraction and cement content. However, the trend reversed for the content of coarse tailings and gravel. Contribution of the four factors to yield stress in descending order is mass fraction > content of gravel > content of coarse tailings > cement versus other tailings ration. Effect of solid components on the yield stress of CPB is mainly due to the different flocculation structure inside the CPB. These various flow structures result in the different free-water content of CPB, leading to a different yield stress value.

scholarly journals Shear thinning and thickening of cemented paste backfill

2019 ◽  
Vol 29 (1) ◽  
pp. 80-93 ◽  
Author(s):  
Liuhua Yang ◽  
Hongjiang Wang ◽  
Aixiang Wu ◽  
Hong Li ◽  
Arlin Bruno Tchamba ◽  
...  
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Yield Stress ◽  
Shear Thinning ◽  
High Shear ◽  
Cemented Paste Backfill ◽  
Concentrated Suspension ◽  
History Effects ◽  
Paste Backfill ◽  
Shear History

Abstract Cemented paste backfill (CPB) is considered to be a concentrated suspension in which tailings are bonded together by the hydraulic binder and water, and it has a high solid volume concentration (≥50 vol.%). Although the shear thinning and thickening of CPB has been extensively reported in literature, the shear history effects have been ignored in previous studies. In this paper, by using rheometer and Focused Beam Reflectance Measurement, the relationship between the rheological properties and microstructure of the paste under different shear histories was studied. The results have shown that at a low shear rate, CPB revealed shear thinning, low yield stress and low index parameters; while exhibited shear thickening, high yield stress and high consistency index when at high shear rates of shear history. This agreed with the general trends shown in the FBRM analysis. It was proposed that the action of shear is beneficial to particle dispersion, whereas a high shear rate history tends to promote the aggregation of particles. It was revealed that both shear thinning and thickening of paste are related to the situation of particles (flocculation, dispersion and aggregation), and shear history effects play an important role in rheological properties of CPB.

scholarly journals Rheological Properties of Cemented Paste Backfill with Alkali-Activated Slag

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 288 ◽  
Author(s):  
Yunpeng Kou ◽  
Haiqiang Jiang ◽  
Lei Ren ◽  
Erol Yilmaz ◽  
Yuanhui Li
Keyword(s):  
Yield Stress ◽  
Rheological Behavior ◽  
Plastic Viscosity ◽  
Molar Ratio ◽  
Cemented Paste Backfill ◽  
Lower Yield Stress ◽  
Alkali Activated Slag ◽  
Paste Backfill ◽  
Activated Slag ◽  
Alkali Activated

This study investigates the time-dependent rheological behavior of cemented paste backfill (CPB) that contains alkali-activated slag (AAS) as a binder. Rheological measurements with the controlled shear strain method have been conducted on various AAS-CPB samples with different binder contents, silicate modulus (Ms: SiO2/Na2O molar ratio), fineness of slag and curing temperatures. The Bingham model afforded a good fit to all of the CPB mixtures. The results show that AAS-CPB samples with high binder content demonstrate a more rapid rate of gain in yield stress and plastic viscosity. AAS-CPB also shows better rheological behavior than CPB samples made up of ordinary Portland cement (OPC) at identical binder contents. It is found that increasing Ms yields lower yield stress and plastic viscosity and the rate of gain in these parameters. Increases in the fineness of slag has an adverse effect on rheological behavior of AAS-CPB. The rheological behavior of both OPC- and AAS-CPB samples is also strongly enhanced at higher temperatures. AAS-CPB samples are found to be more sensitive to the variation in curing temperatures than OPC-CPB samples with respect to the rate of gain in yield stress and plastic viscosity. As a result, the findings of this study will contribute to well understand the flow and transport features of fresh CPB mixtures under various conditions and their changes with time.

scholarly journals Investigation on Mechanical Characteristics and Microstructure of Cemented Whole Tailings Backfill

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 592
Author(s):  
Armelle Estelle Belibi Tana ◽  
Shenghua Yin ◽  
Leiming Wang
Keyword(s):  
Yield Stress ◽  
Mechanical Characteristics ◽  
Xrd Analysis ◽  
Solid Content ◽  
Chemical Components ◽  
Cemented Paste Backfill ◽  
Before And After ◽  
Paste Backfill ◽  
Solids Content ◽  
Rheological Test

A paste backfill performance can be primarily evaluated through the mechanical and physical characteristics of the components involved. In this study, the effects of solid components’ tailings, binders and waters contents on microstructural evolution and mechanical properties of uncemented whole tailings backfill (CWTB) mixtures were investigated. Different mixtures of ordinary Portland cement of 1, 3 and 5 wt. % and solid concentrations at 72 wt. %, 74 wt. % and 75 wt. % were selected and rheological test was conducted to define the slump fluidity and yield stress. The microstructure of the solid component before and after the preparation and chemical composition were analyzed by the Scanning electron microscope and XRD analysis, respectively. The results show that a positive correlation between yield stress and slump values of CWTB paste slurries, the decrease of flow consistence leads to the reduction of the water content on the CWTB mixtures and the flow resistance of the paste. With the highest solids content, unconfined compressive strength (UCS) of CWTB varies between 0.1–0.9 MPa. Increasing the solid content affects the porosity and improves the strength resistance of CWTB mixtures. The findings in this study can therefore lead us to a statement that CWTB chemical components seem to be an important factor in cemented paste backfill (CPB) design and mine operations.

scholarly journals Specific Mixing Energy of Cemented Paste Backfill, Part II: Influence on the Rheological and Mechanical Properties and Practical Applications

Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1159
Author(s):  
Reagan Kabanga Dikonda ◽  
Mamert Mbonimpa ◽  
Tikou Belem
Keyword(s):  
Mechanical Properties ◽  
Rheological Properties ◽  
Yield Stress ◽  
Specific Energy ◽  
Distribution System ◽  
Flow Index ◽  
Cemented Paste Backfill ◽  
Practical Applications ◽  
Mixing Energy ◽  
Paste Backfill

The rheological properties (yield stress, flow index and infinite dynamic viscosity) and mechanical properties (unconfined compressive strength, UCS) of different cemented paste backfill (CPB) recipes must be determined during the laboratory optimization phase. However, the influence of the mixing procedure on these properties has scarcely been studied so far. The objective of this paper is to assess to what extent these properties depend on the specific mixing energy (SME) for a given type of mixer. CPB recipes were prepared based on two types of tailing (CPB-T1 and CPB-T2, also referred to as T1 and T2) at a fixed solid percentage for each type of tailing using the Omcan laboratory mixer. A mixture of 80% slag and 20% GU was used as a binder. The mixing time and the rotation speed of the mixer were successively varied. For each recipe prepared, we determined the SME, the rheological properties of fresh CPB (at the end of mixing) and the UCS at 7, 28 and 90 days of curing. The results show that yield stress and infinite viscosity decreased when SME increased in an interval going from 0.3 to 3.8 Wh/kg and 0.6 to 6 Wh/kg for CPB-T1 and CPB-T2, respectively. An increasing trend in UCS with increasing SME was also observed. Empirical equations describing the change of the rheological properties with the SME are used to estimate the change in rheological properties of CPB along the distribution system, considering the specific energy dissipation during CPB transportation. A mixing procedure for obtaining CPB mixtures that are representative of CPB deposited in underground mine stopes is suggested for laboratories who currently use a same mixing procedure, irrespective of the variable field specific energy.

scholarly journals Analysis of damage failure in uniaxial compressive of cemented paste backfill by ultrasonic pulse velocity test

2021 ◽  
Vol 37 (2) ◽  
Author(s):  
B. Wang ◽  
L. Li ◽  
Y. Yu ◽  
B. Huo ◽  
J. Liu
Keyword(s):  
Mass Fraction ◽  
Damage Mechanics ◽  
Microstructural Analysis ◽  
Ultrasonic Pulse Velocity ◽  
Cementitious Materials ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Experimental Results ◽  
Cemented Paste Backfill ◽  
Paste Backfill

Cemented paste backfill (CPB) is prepared by mixing cementitious materials, tailings and water. Uniaxial compressive strength (UCS) is one of the most commonly used indicators for evaluating the mechanical performance of CPB. Ultrasonic pulse velocity (UPV) testing which is a non-destructive measurement, can also be applied to determine the mechanical properties of cement-based materials such as CPB. In order to study the failure mechanism of CPB,144 CPB samples prepared at different mass fraction and cement-tailing ratios were subjected to the UCS and UPV tests at 7,14 and 28 days of curing age. The effect of cement-tailing ratio and mass fraction on the UCS and UPV of CPB samples were obtained, the UCS values were correlated with the corresponding UPV data. Microstructural analysis was also performed on CPB samples to understand the effect of microstructure on the UCS data. The results show that the UCS and UPV values of CPB increased with cement-tailing ratio, mass fraction and curing time. Based on the experimental results, the damage constitutive equations and the damage evolution equations of different backfills were proposed on the basis of damage mechanics. Moreover, comparative analysis of constitutive model and experimental results were made to verify the reliability of the damage model. The results acquired by this paper provide a scientific basis for the rational strength design of backfill mine.

Effect of particle gradation characteristics on yield stress of cemented paste backfill

2020 ◽  
Vol 27 (1) ◽  
pp. 10-17 ◽  
Author(s):  
Hai-yong Cheng ◽  
Shun-chuan Wu ◽  
Xiao-qiang Zhang ◽  
Ai-xiang Wu
Keyword(s):  
Yield Stress ◽  
Cemented Paste Backfill ◽  
Paste Backfill
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