Microscopic characteristics of the action of an air entraining agent on cemented paste backfill pores

Hu, Jianhua; Zhao, Fengwen; Kuang, Yuanyuan; Yang, Dongjie; Zheng, Minghua; Zhao, Lei

doi:10.1016/j.aej.2020.04.005

Cited by 27 publications

(10 citation statements)

References 13 publications

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“…Figure 6 a is the original SEM image, Figure 6 b is Threshold image, and Figure 6 c is the binaryzation image of the SEM image. The binarization principle follows the following principles; the binarization formula is [ 24 , 25 ]:

where T is the gray threshold, 0 represents the solid phase—i.e., black—and 1 represents the pore, i.e., white. It can be seen from Figure 6 that the pore shapes were all different, with a small number of regular shapes and mostly irregular shapes.…”

Section: Resultsmentioning

confidence: 99%

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Study of the Macro and Micro Characteristics of and Their Relationships in Cemented Backfill Based on SEM

Zhao

Liu

et al. 2023

Materials

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Nuclear magnetic resonance can only quantitatively obtain porosity and pore size distribution, but as a conventional microstructure observation technology, scanning electron microscope (SEM) can select different magnifications to observe the microstructure of backfill materials. However, the processing of SEM images is not deep enough. In this paper, Image-Pro Plus 6.0 software was used to extract the data from SEM images, and the parameters of the area, and the perimeter, aspect ratio and roundness of the pores in the SEM images were obtained. The fractal characteristics of the pores in the SEM image were obtained by using the slit island method fractal theory. The concretization and quantification analysis of the pores’ complexity were achieved. A functional relationship model for the strength and pore parameters was constructed; thus, the influence law of pore characteristics on strength was quantitatively analyzed. The conclusions included: (1) Pore parameters indicate that most pores in backfill are irregular, and only a few pores are regular—however, the whole structure has good fractal characteristics (R2 > 0.96). (2) The fractal dimension of pores is directly proportional to the roundness, the aspect ratio, and the pore content of pores—which indicates that the complexity of pores is related to both pore shape and pore content. (3) The strength had a linear inverse relationship with the roundness, aspect ratio, pore content, and fractal dimension—which indicates that all characteristics of pores have a certain influence on the strength.

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Section: Resultsmentioning

confidence: 99%

“…Figure 6a is the original SEM image, Figure 6b is Threshold image, and Figure 6c is the binaryzation image of the SEM image. The binarization principle follows the following principles; the binarization formula is [24,25]:…”

Section: Sem Characteristicsmentioning

confidence: 99%

Study of the Macro and Micro Characteristics of and Their Relationships in Cemented Backfill Based on SEM

Zhao

Liu

et al. 2023

Materials

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“…e combination of fractal theory and NMR can be used to study the pore characteristics in the AEACPB, so as to explain the change of strength from the complexity of pores. ere is a certain functional relationship between the fractal dimension D and T 2 , and the relationship is as follows [15,19]:…”

Section: E Relationship Between Fractal Dimension and Ucsmentioning

confidence: 99%

“…Note that it can change the pore structure in the backfill under the condition that the ratio of other materials remains unchanged so as to achieve an individual change of pores in the same age and achieve the purpose of artificially controlling the pore structure. Studies report that adding AEA to the pore material can effectively change the pore structure and improve the material's performance [13][14][15]. Furthermore, we performed quantitative description of pore structure to analyze the effect of pore on strength.…”

Section: Introductionmentioning

confidence: 99%

Study on the Relationship between Pore Structure and Uniaxial Compressive Strength of Cemented Paste Backfill by Using Air‐Entraining Agent

Zhao

Yang

et al. 2021

Advances in Civil Engineering

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To control pores in the backfill, the air-entraining agents (AEAs) are used as an admixture to realize the pore structure changes under artificial action and explore the effect of pore structure on strength. Two AEAs at different dosages were added to the backfill. The relationship was then analyzed between them from the macro- and mesoscopic aspects. The results indicate that AEA can regulate pore structure changes of AEACPB. With the increase in AEA content, the total pore volume of different pore sizes in AEACPB increases, in which the proportion of big and medium pore gradually increases while the proportion of small pore gradually decreases. The AEACPB’s UCS is linearly negatively correlated with the porosity and pore percentage, which is the primary factor affecting the AEACPB of the pore structure. When the total pores’ volume in the AEACPB is constant, the influence of different pore structures differs. A higher proportion of small pores leads to a linear increase in strength; a higher proportion of medium pores leads to a linear decrease in strength; and a higher proportion of big pores leads to an exponential decrease in strength. And the fractal dimension has a linear negative correlation with the UCS by fractal theory analysis.

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“…e pumping agent is generally mainly composed of water-reducing agent and airentraining agent (AEA). Air-entraining agent will increase the air content (the percentage in air volume/total slurry volume) in the slurry, thereby increasing the pores in the CPB, which will have a certain impact on the CPB strength [14,15].…”

Section: Introductionmentioning

confidence: 99%

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

Zhang

Gan

Zhi

et al. 2020

Advances in Materials Science and Engineering

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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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Microscopic characteristics of the action of an air entraining agent on cemented paste backfill pores

Cited by 27 publications

References 13 publications

Study of the Macro and Micro Characteristics of and Their Relationships in Cemented Backfill Based on SEM

Study of the Macro and Micro Characteristics of and Their Relationships in Cemented Backfill Based on SEM

Study on the Relationship between Pore Structure and Uniaxial Compressive Strength of Cemented Paste Backfill by Using Air‐Entraining Agent

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

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