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.

Saturated hydraulic conductivity of cemented paste backfill

2009 ◽  
Vol 22 (15) ◽  
pp. 1307-1317 ◽  
Author(s):  
M. Fall ◽  
D. Adrien ◽  
J.C. Célestin ◽  
M. Pokharel ◽  
M. Touré
Keyword(s):  
Hydraulic Conductivity ◽  
Saturated Hydraulic Conductivity ◽  
Cemented Paste Backfill ◽  
Paste Backfill

scholarly journals Mine Backfilling in the Permafrost, Part I: Numerical Prediction of Thermal Curing Conditions within the Cemented Paste Backfill Matrix

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 165 ◽  
Author(s):  
Fabrice Beya ◽  
Mamert Mbonimpa ◽  
Tikou Belem ◽  
Li Li ◽  
Ugo Marceau ◽  
...  
Keyword(s):  
Temperature Field ◽  
Numerical Models ◽  
Three Dimensional ◽  
Equilibrium Temperature ◽  
Cemented Paste Backfill ◽  
Thermal Curing ◽  
Curing Conditions ◽  
Permafrost Rock ◽  
Thermal Boundary Conditions ◽  
Paste Backfill

The mechanical behavior of cemented paste backfill (CPB) in permafrost regions may depend on the thermal curing conditions. However, few experimental data are available for calibrating and validating numerical models used to predict these conditions. To fill this gap, a three-dimensional (3D) laboratory heat transfer test was conducted on CPB placed in an instrumented barrel and cured under a constant temperature of −11 °C. Results were used to calibrate and validate a numerical model built with COMSOL Multiphysics®. The model was then used to predict the evolution of the temperature field for CPB cured under the thermal boundary conditions for a backfilled mine stope in the permafrost (at −6 °C). Numerical results indicated that the CPB temperature gradually decreased with time such that the entire CPB mass was frozen about five years after stope backfilling. However, the permafrost equilibrium temperature of −6 °C was not reached throughout the entire CPB mass even after 20 years of curing. In addition, the evolution of the temperature field in the permafrost rock showed that the thickness of the thawed portion reached about 1 m within 120 days. Afterwards, the temperature continues to drop over time and the thawed portion of the permafrost refreezes after 365 days.

Combined effect of SCMs and curing temperature on mechanical properties of high-strength strain-hardening cementitious composites

2021 ◽  
pp. 073168442110517
Author(s):  
Hong-Joon Choi ◽  
Min-Jae Kim ◽  
Doo-Yeol Yoo
Keyword(s):  
Mechanical Properties ◽  
Strain Hardening ◽  
High Strength ◽  
Curing Temperature ◽  
Supplementary Cementitious Materials ◽  
Partial Replacement ◽  
Multiple Cracks ◽  
Curing Conditions ◽  
Starting Point ◽  
Tensile Performance

This study was conducted to evaluate the curing temperature effect on the mechanical properties of high-strength strain-hardening cementitious composite (SHCC) containing waste supplementary cementitious materials (SCMs) and polyethylene (PE) fibers. High-strength SHCC is developed to extend the strain-hardening interval by simultaneously inducing multiple cracks and ensuring the durability and strength of high-strength concrete. The starting point of this study was to enhance the tensile performance and durability of high-strength SHCC by utilizing various SCMs. In addition, the optimal curing conditions were investigated to derive the maximum material potential of each SCM, which aims to advance the performance of high-strength SHCC. The temperatures employed for the curing process were 20, 40, and 90°C. Moreover, ground granulated blast-furnace slag (GGBS), silica fume (SF), and cement kiln dust (CKD), were used as a partial replacement for cement to determine the best mix for achieving optimal tensile performance. Four mix designs were prepared, including a plain test specimen composed entirely of cement as binder; therefore, a total of 12 types of specimens were set considering the three curing temperatures. A compressive strength test was conducted with cube specimens, and a direct tensile test was performed with dog-bone-shaped specimens. Derivative thermogravimetry (DTG) and energy dispersive X-ray spectroscopy (EDS) mapping were conducted to identify the microstructures. The SF-containing SHCC cured at 90°C exhibited the best tensile performance in terms of deformability and energy absorption capacity by achieving the highest strain capacity of 4.37% and g-value of 294.5 kJ/m3. In addition, the performance of each specimen was reconfirmed based on the DTG, EDS mapping, and crack pattern results. Through these results, the optimal SCM mixing amount and curing conditions that led to noticeable performance improvement of high-strength SHCC were identified.

scholarly journals Coupled Effect of Curing Temperature and Moisture on THM Behavior of Cemented Paste Backfill

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Wenyuan Xu ◽  
Runkang Zhao ◽  
Xiaocong Yang ◽  
Lijie Guo ◽  
Chaowu Xie ◽  
...  
Keyword(s):  
Model Simulation ◽  
Cost Effective ◽  
Curing Temperature ◽  
Underground Mines ◽  
Cemented Paste Backfill ◽  
Waste Discharge ◽  
Stress Strain Relation ◽  
Paste Backfill ◽  
Simulation And Experiment ◽  
As Stress

Cemented paste backfill (CPB), a mixture of tailings, binder, and water, is widely and continually utilized in underground mines for subsidence control and disposal of surface hazardous waste discharge. The mechanical strength of CPB, which is the key for the backfill structure to play the role of supporting overlying roof and controlling subsidence, is governed by complex factors (thermal, hydraulic, and mechanical loads), particularly strongly affected by the environmental conditions, such as ambient temperature and humidity. Thus, it is crucial to understand and assess the response of CPB subjected to the loads mentioned above, so as to better ascertain its performance and obtain a cost-effective, safe, and stable CPB structure. Accordingly, a coupled THM model is developed to describe and analyze the performance of CPB. Comparisons between model simulation and experiment data prove the capability of the developed model in predicting the evolutions of temperature and internal relative humidity, as well as stress-strain relation of CPB. The obtained results indicate that all these properties are significantly affected by ambient humidity and temperature.

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