scholarly journals Ensemble Learning Regression for Estimating Unconfined Compressive Strength of Cemented Paste Backfill

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 72125-72133 ◽  
Author(s):  
Xiang Lu ◽  
Wei Zhou ◽  
Xiaohua Ding ◽  
Xuyang Shi ◽  
Boyu Luan ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Ensemble Learning ◽  
Unconfined Compressive Strength ◽  
Cemented Paste Backfill ◽  
Paste Backfill

Effect of specimen composition on the strength development in cemented paste backfill

2006 ◽  
Vol 43 (3) ◽  
pp. 310-324 ◽  
Author(s):  
Katherine Klein ◽  
Dragana Simon
Keyword(s):  
Compressive Strength ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Unconfined Compressive Strength ◽  
Pore Fluid ◽  
Strength Development ◽  
Cemented Paste Backfill ◽  
Pore Fluid Chemistry ◽  
Paste Backfill

This paper focuses on monitoring setting and strength development in cemented paste backfill (CPB). The composition of the paste is altered to study the effects of binder type and content, selected chemical admixtures (superplasticizers), mineral additives (e.g., fly ash), and pore fluid chemistry (e.g., ionic concentration and pH) on these properties. The three main techniques utilized are shear wave velocity measurements, penetration tests (e.g., Vicat needle tests), and unconfined compressive strength tests. All of these tests are sensitive to changes in the paste composition. The effect of the pore fluid chemistry and the chemical additives on the CPB properties depends on the ion type and concentration and the chemical composition of the superplasticizers. The shear wave velocity in both uncemented and cemented pastes increases with time as a result of self-weight consolidation, capillary forces, and cementation (the precipitation of ions in uncemented tailings pastes or cement hydration in cemented tailings pastes).Key words: cemented paste backfill, shear wave velocity, setting, unconfined compressive strength.

scholarly journals Mine Backfilling in the Permafrost, Part II: Effect of Declining Curing Temperature on the Short-Term Unconfined Compressive Strength of Cemented Paste Backfills

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 172
Author(s):  
Mamert Mbonimpa ◽  
Parrein Kwizera ◽  
Tikou Belem
Keyword(s):  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Room Temperature ◽  
Freezing Temperature ◽  
Curing Temperature ◽  
Strength Development ◽  
Short Term ◽  
Practical Applications ◽  
Humidity Chamber ◽  
Paste Backfill

When cemented paste backfill (CPB) is used to fill underground stopes opened in permafrost, depending on the distance from the permafrost wall, the curing temperature within the CPB matrix decreases progressively over time until equilibrium with the permafrost is reached (after several years). In this study, the influence of declining curing temperature (above freezing temperature) on the evolution of the unconfined compressive strength (UCS) of CPB over 28 days’ curing is investigated. CPB mixtures were prepared with a high early (HE) cement and a blend of 80% slag and 20% General Use cement (S-GU) at 5% and 3% contents and cured at room temperature in a humidity chamber and under decreasing temperatures in a temperature-controlled chamber. Results indicate that UCS is higher for CPB cured at room temperature than under declining temperatures. UCS increases progressively from the stope wall toward the inside of the CPB mass. Under declines in curing temperature, HE cement provides better short-term compressive strength than does S-GU binder. In addition, the gradual decline in temperature does not appear to affect the fact that the higher the binder proportion, the greater the strength development. Therefore, UCS is higher for samples prepared with 5% than 3% HE cement. Findings are discussed in terms of practical applications.

scholarly journals Effect of the Initial Air Content in Fresh Slurry on the Compressive Strength of Hardened Cemented Paste Backfill

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Youzhi Zhang ◽  
Deqing Gan ◽  
Zhenlin Xue ◽  
Xun Chen ◽  
Sheng Hu
Keyword(s):  
Compressive Strength ◽  
Sodium Dodecyl ◽  
Contact Structures ◽  
Cemented Paste Backfill ◽  
Mining Method ◽  
Force Analysis ◽  
Air Content ◽  
Ground Pressure ◽  
Paste Backfill ◽  
The Mathematical Model

Filling mining method can dispose of the tailings into filling slurry, which can be transported to the stope through pipelines to manage the ground pressure and protect the environment. To improve the flowability of filling slurry, additives are used more and more widely. However, some additives can increase the air content in the slurry. The air in the slurry will become pores in the hardened cemented paste backfill (CPB). Therefore, it is necessary to explore the influence of initial air content in fresh slurry on the compressive strength of CPB. In this paper, sodium dodecyl sulfate (SDS) was used to regulate the air content in the fresh slurry. After measuring the initial air content, the slurry was made into test blocks. Then, the uniaxial compressive strength (UCS) of CPB at 28 d age was tested, and the distribution of CPB microscopic pores was observed by scanning electron microscope (SEM). The results show that as the initial air content in fresh slurry increases, the UCS of CPB first increases and then decreases. Before the initial air content in fresh slurry is 6.03%, the CPB pores distribution is relatively uniform. However, after exceeding this value, “discontinuous contact” structures, pore groups, and macropores occur in CPB. Through the CPB microscopic force analysis, the mathematical model describing the effect of initial air content on UCS of CPB should be a combination of logarithmic function and quadratic polynomial. This work can provide a supplement to the theory of CPB strength.

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