Strengthening Behavior of Cemented Paste Backfill Using Alkali-Activated Slag Binders and Bottom Ash Based on the Response Surface Method

Sun, Qi; Wei, Xueda; Li, Tianlong; Zhang, Lu

doi:10.3390/ma13040855

Cited by 19 publications

(9 citation statements)

References 34 publications

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“…These substances are the main source of early compressive strength in the CPB samples. In addition, a large amount of irregular needle-like material is visible at point A, which was found to be dissolved slag based on the EDS analysis in Figure 13 a [ 31 ]. Due to the insufficient dissolution of the slag and the low content of polymerized products, the internal pores of the CPB sample were poorly filled.…”

Section: Resultsmentioning

confidence: 99%

“…We determined that the material contained a large amount of iron from the C–S–H gel. The internal pores of the CPB samples were fully filled with C–S–H, C–A–S–H, and crystals; the connections are more compact; and the compressive strength reached the maximum value at all ages, indicating that aluminosilicate hydrates determined the compressive strength of the CPB samples [ 31 ].…”

Section: Resultsmentioning

confidence: 99%

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Preparation and Strength Formation Mechanism of Calcined Oyster Shell, Red Mud, Slag, and Iron Tailing Composite Cemented Paste Backfill

Sun

2022

Materials

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The use of bulk solid-waste iron tailing (IOT), red mud (RM), and oyster shells to prepare cemented paste backfill (CPB) can effectively solve the ecological problems caused by industrial solid waste storage and improve the utilization rate of such materials. In this study, a new type of CPB was prepared by partially replacing slag with RM, with calcined oyster shell (COS) as the alkaline activator and IOT as aggregate. The central composite design (CCD) method was used to design experiments to predict the effects of the COS dosage, RM substitution rate, solid mass, and aggregate–binder ratio using 28-dUCS, slump, and the cost of CPB. In this way, a regression model was established. The quantum genetic algorithm (QGA) was used to optimize the regression model, and X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS) microscopic tests are performed on CPB samples of different ages with the optimal mix ratio. The results showed that COS is a highly active alkaline substance that provides an alkaline environment for polymerization reactions. In the alkaline medium, the hematite and goethite in RM and quartz in IOT gradually dissolved and participated in the process of polymerization. The main polymerization products of the CPB samples are calcium–silicate–hydrogel (C–S–H), calcium–aluminosilicate–hydrogel (C–A–S–H), and aluminosilicate crystals such as quartz, albite, and foshagite. These products are intertwined and filled in the internal pores of the CPB, enabling the pore contents to decrease and the interiors of the CPB samples to gradually connect into a whole. In this way, the compressive strength is increased.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Preparation and Strength Formation Mechanism of Calcined Oyster Shell, Red Mud, Slag, and Iron Tailing Composite Cemented Paste Backfill

Sun

2022

Materials

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“…When there is a crystalline phase such as Fe 2 O 3 , only 20 to 30% of the coal ash is in a crystalline state and the rest is present in a glassy state. Except for quartz, which does not undergo chemical deformation at high temperatures and instead mostly retains its original shape, most of the minerals in coal are generally broken down during combustion [ 26 , 27 ]. In other words, clay minerals lose water and are dissociated into various types of glassy or amorphous components in the cooling process.…”

Section: Test Results and Discussionmentioning

confidence: 99%

An Evaluation of the Physical and Chemical Stability of Dry Bottom Ash as a Concrete Light Weight Aggregate

Kim

Shin

2021

Materials

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Compared to the bottom ash obtained by a water-cooling system (wBA), dry process bottom ash (dBA) makes hardly any unburnt carbon because of its stay time at the bottom of the boiler and contains less chloride because there is no contact with seawater. Accordingly, to identify the chemical stability of dBA as a lightweight aggregate for construction purposes, the chemical properties of dBA were evaluated through the following process of the reviewing engineering properties of a lightweight aggregate (LWA). Typically, river gravel and crushed gravel have been used as coarse aggregates due to their physical and chemical stability. The coal ash and LWA, however, have a variety of chemical compositions, and they have specific chemical properties including SO3, unburnt coal and heavy metal content. As the minimum requirement to use the coal ash and lightweight aggregate with various chemical properties for concrete aggregate, the loss on ignition, the SO3 content and the amount of chloride should be examined, and it is also necessary to examine heavy metal leaching even though it is not included in the standard specifications in Korea. Based on the results, it is believed that there are no significant physical and chemical problems using dBA as a lightweight aggregate for concrete.

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“…The strength of the backfill body is an important parameter in the backfill design, especially when the backfill body plays a supporting role to ensure the subsequent safe mining [21][22][23][24]. Some scholars optimized the mixture proportion of backfill materials by using RMS to study the influential behaviors of variable factors and their interaction on backfill strength at different curing ages [25][26][27]. Among massive backfill parameters, backfill strength is critical to maintaining the stability of stopes and rock mass adjacent to the mined-out areas.…”

Section: Introductionmentioning

confidence: 99%

Multi-Objective Function Optimization of Cemented Neutralization Slag Backfill Strength Based on RSM-BBD

et al. 2022

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Tailings produced in the beneficiation of Carlin-type gold deposits are characterized by fine particle size and high mud content. When neutralized with wasted acid generated by pressurized pre-oxidation, the tailings turn to neutralized slag and perform as a novel backfill material. To understand the influential behavior of variable factors on the strength and its optimization of cemented neutralization slag backfill, RMS-BBD design test was carried out with 56–60% slurry mass fraction, 12.5–25% cement/(neutralization slag + waste rock) (i.e., C/(S+R)) and 30–40% waste rock content. A modified three-dimensional quadratic regression model was proposed to predict the strength of cemented neutralization slag backfill. The results showed that backfill strength predicted by the modified ternary quadratic regression model was in high coincidence with the data of backfill mixture tests. C/(S+R) was predominant in backfill strength with regard to every single influential factor throughout the curing age, and the mass fraction of slurry had a significant effect on the later strength. From the perspective of economic and engineering operation, a multi-objective function method was further introduced to optimize the backfill strength. The optimal mixture proportion of cemented neutralized slag backfill slurry was: 58.4% slurry mass fraction, 32.2% waste rock content, and 20.1% C/(S+R). The backfill strength of this mixture proportion on days 7, 28 and 56 was verified as 0.42, 0.64 and 0.85 MPa, respectively. RSM-BBD design and multi-objective function optimization proposed a reliable way to evaluate and optimize the strength of neutralized slag backfill with high mud content.

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Strengthening Behavior of Cemented Paste Backfill Using Alkali-Activated Slag Binders and Bottom Ash Based on the Response Surface Method

Cited by 19 publications

References 34 publications

Preparation and Strength Formation Mechanism of Calcined Oyster Shell, Red Mud, Slag, and Iron Tailing Composite Cemented Paste Backfill

Preparation and Strength Formation Mechanism of Calcined Oyster Shell, Red Mud, Slag, and Iron Tailing Composite Cemented Paste Backfill

An Evaluation of the Physical and Chemical Stability of Dry Bottom Ash as a Concrete Light Weight Aggregate

Multi-Objective Function Optimization of Cemented Neutralization Slag Backfill Strength Based on RSM-BBD

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