Effects of Superplasticizer on the Hydration, Consistency, and Strength Development of Cemented Paste Backfill

Jian, Zhang; Deng, Hongwei; Taheri, Abbas; Deng, Junren; Ke, Bo

doi:10.3390/min8090381

Cited by 59 publications

(43 citation statements)

References 32 publications

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“…According to the experimental program in Table 3, a high-frequency vibration table and a mixer were first used to mix the cement and water for 10 min [74], which formed a uniform slurry that was then mixed with the prepared particles for 10 min [75], then poured into the device to produce a cemented rockfill specimen. The entire device must be fixed and then placed on a vibratory table for 5 min to optimize the specimen's homogeneity [76]. The curing conditions of the cemented rockfill specimen were maintained at a humidity of 95% and temperature of 25 • C for seven days [77].…”

Section: Amentioning

confidence: 99%

Particle Size Distribution of Cemented Rockfill Effects on Strata Stability in Filling Mining

et al. 2018

Minerals

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It is of great significance for engineering safety, economic benefits, environmental protection, and sustainable development to investigate the strata stability in filling mining with cemented rockfill. Consequently, this paper is based on a specific coal mine where we applied the fully-mechanized longwall mining and filling and designed a cemented rockfill material for which the particles satisfied the Talbot gradation. Uniaxial and triaxial compression experiments were carried out on the cemented rockfill specimen, which obtained the relations between the mechanical parameters (Poisson ratio, elastic modulus, compressive strength, cohesive force, internal friction angle, and tensile strength) and the particle size distribution of the aggregate. The excavation and filling processes in the coal seam were simulated based on the numerical software FLAC3D. The characteristics of the displacement and stress fields of the strata when the goaf was filled by cemented rockfill with different granule gradations were discussed. The influences of the particle size distribution and mining distance on the maximum subsidence displacement of the coal seam roof, internal stress of the backfill, and the stress of the rock mass in the coalface were analyzed. The feasibility and effectiveness of the filling mining with cemented rockfill to protect the integrity of the overlying strata were discussed. The results showed that optimizing the particle size distribution of the aggregate in cemented rockfill could increase the loading capacity of the backfill to improve the filling effect, effectively control the strata movement, and decrease the stress of rock mass in the coalface to reduce the potential danger.

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Section: Amentioning

confidence: 99%

Particle Size Distribution of Cemented Rockfill Effects on Strata Stability in Filling Mining

et al. 2018

Minerals

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“…coal mine roof [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Already, many significant results have been obtained.…”

Section: Methodsmentioning

confidence: 99%

“…The physical and mechanical properties of the cemented composites are influenced, not only by the cementing materials, but also by the structure of the cemented composite. At present, research on goaf treatment mainly focuses on the development and selection of filling materials, mechanical properties of filling materials and surrounding rock, and evaluation and control of the stability of the coal mine roof [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Already, many significant results have been obtained.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Characteristics and Failure Prediction of Cement Mortar with a Sandwich Structure

Liu

Tan

et al. 2019

Minerals

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It is necessary to master the mechanical properties and failure prediction of the composite of mortar and rock block in a mined-out area. In this study, uniaxial compression and acoustic emission (AE) synchronous tests of mortar specimens with different sandwich materials and cement–sand ratios were carried out. The results showed that the compressive strength and elastic modulus of mortar specimens increased with an increase in the cement–sand ratio and the stiffness of the sandwich material. The AE counts and energy of mortar specimens with a high-stiffness sandwich material were maximum when they were destroyed. The b value, a number that reflects the extent of fracture propagation, decreased first and then increased with the increase in strain. The inflection point of the b value can be taken as the indication of the imminent failure of the mortar. A method for determining the b value at the turning point was proposed and verified.

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“…In China, backfilling mining has made great achievements, including gangue backfilling material, cemented paste material and high-water-content materials [1][2][3][4]. Meanwhile, retained gob-side entry (RGE) is a significant development for longwall mining without leaving gate pillar unmined.…”

Section: Introductionmentioning

confidence: 99%

Vertical Stress and Deformation Characteristics of Roadside Backfilling Body in Gob-Side Entry for Thick Coal Seams with Different Pre-Split Angles

et al. 2019

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Retained gob-side entry (RGE) is a significant improvement for fully-mechanized longwall mining. The environment of surrounding rock directly affects its stability. Roadside backfilling body (RBB), a man-made structure in RGE plays the most important role in successful application of the technology. In the field, however, the vertical deformation of RBB is large during the panel extraction, which leads to malfunction of the RGE. In order to solve the problem, roof pre-split is employed. According to geological conditions as well as the physical modeling of roof behavior and deformation of surrounding rock, the support resistance of RBB is calculated. The environment of surrounding rock, vertical stress and vertical deformation of the RBB in the RGE with different roof pre-split angles are analyzed using FLAC 3D software. With the increase of roof pre-split angle, the vertical stresses both in the coal wall and RBB are minimum, and the vertical deformation of RBB also decreases from 110.51 mm to 6.1 mm. Therefore, based on the results of numerical modeling and field observation, roof pre-split angle of 90 • is more beneficial to the maintenance of the RGE.Energies 2019, 12, 1316 2 of 16 deformation. Using the numerical simulation, break position and shape of the main roof along the RGE, the influence of different support methods on the roof movement and the relevant technical parameters of RBB were analyzed [18,19]. Tan et al. (2015) studied the stability of RBB under hard roof condition by using flexible-hard support model for RGE [20]. Zhang et al. (2015) analyzed high-water packing materials in RGE using numerical analysis, and the optimal width of the RBB was analyzed [21].There are also many studies involving problems in using the technology, such as serious deformation of RBB [22][23][24]. Using the dynamic analysis software LS-DYNA (Livermore Software Technology Corporation, Livermore, CA, USA) and theoretical analysis, Gao et al. (2013) analyzed the pressure relief mechanism of the induced roof caving by deep-hole blasting. It was found that the deep-hole-blasting can effectively reduce the load transferred to RBB and is more conducive to the maintenance of RGE [25]. Zhao et al. (2015) proposed the optimal control technology of surrounding rock structure through the following methods. First, the hard roof ahead of the working face is pre-split using deep holes. Then overhanging roof at gob side is broken so as to release the pressure by deep-hole blasting. The control technology has been successfully applied in Pingdingshan No. 12 coal mine [26]. Sun et al. studied the key parameters including height, angle, and length of deep-holes for roof breakage and pressure relief [27].However, most studies on RGE are against thin coal seam mining. It has been shown that RGE can achieve good results in thin coal seams. However, in thick coal seams using the fully mechanized longwall top coal caving (FMLTCC), the situation of the RBB is quite different. In this paper, using FLAC 3D (Itasca: Minneapolis, MN, USA), vert...

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Effects of Superplasticizer on the Hydration, Consistency, and Strength Development of Cemented Paste Backfill

Cited by 59 publications

References 32 publications

Particle Size Distribution of Cemented Rockfill Effects on Strata Stability in Filling Mining

Particle Size Distribution of Cemented Rockfill Effects on Strata Stability in Filling Mining

Mechanical Characteristics and Failure Prediction of Cement Mortar with a Sandwich Structure

Vertical Stress and Deformation Characteristics of Roadside Backfilling Body in Gob-Side Entry for Thick Coal Seams with Different Pre-Split Angles

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