Environmentally benign production of one-part alkali-activated slag with calcined oyster shell as an activator

Yang, Beomjoo; Jang, Jeong Gook

doi:10.1016/j.conbuildmat.2020.119552

Cited by 38 publications

(19 citation statements)

References 42 publications

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“…The content of calcite (CaCO 3 ) is 7.8%. This calcite was a decryption product of the C–S–H and C–A–S–H amorphous gel [ 6 ], which may be produced by the carbonization of calcium hydroxide.…”

Section: Resultsmentioning

confidence: 99%

“…The peak (Q 2 ) located near 1140 cm −1 is Si–O–T in the C–S–H stretching vibration peaks. Except for the 1-day age, curing age was from 3 days to 28 days, and the (Q 1 ) C–O stretching vibration peak and Q 2 peak located near 1470 cm −1 gradually shifted to a lower wavenumbers direction, indicating that the polymerization degree of carbonated C–S–H increased [ 6 ]. At an age of 1 day, a high degree of polymerization was observed because highly polymerized silicate materials in the precursor had not been fully dissolved, which is consistent with the analysis results of XRD.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, the degree of aggregation was the highest at an age of 1 day. In a previous analysis [ 6 ], the degree of C–A–S–H polymerization is determined by Al/Si; when Al/Si increased, the peak shifted in the direction of a high wavenumbers, and the degree of polymerization decreased. A decrease in Al/Si in C–A–S–H may also indicate the conversion of C–A–S–H to C–S–H.…”

Section: Resultsmentioning

confidence: 99%

“…COS: The oyster shells were taken from the Bohai Sea, Jinzhou City, Liaoning Province, China. The surface attachments were cleaned with a brush, soaked in clean water for 7 days to remove the surface salt, and calcined at 1000 °C for 3 h [ 6 ]. Table 1 shows the XRF test results of COS. Figure 1 shows the particle size curve of COS. Figure 2 shows the mineral composition of COS.…”

Section: Methodsmentioning

confidence: 99%

“…The main component of oyster shell is calcium carbonate. After high-temperature calcination, the content of CaO—an alkaline substance rich in active calcium—can reach more than 90% [ 6 ]. Therefore, the preparation of a new type of CPB using IOT, RM, and COS would solve the adverse impact of bulk solid waste on the environment and be beneficial to sustainable development.…”

Section: Introductionmentioning

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%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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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Effect of fly ash and gypsum on drying shrinkage and mechanical properties of one‐part alkali‐activated slag mortar

Chen,

Zhang,

Chen

et al. 2024

Structural Concrete

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One‐part alkali‐activated materials can be processed into semi‐finished products by mixing a solid activator with the powder. They only require the addition of water, which greatly improves their commercial feasibility. So, we used one‐part alkali‐activated slag mortar to investigate the effects of the dosages of the activator (sodium metasilicate), fly ash (FA), and gypsum on its fluidity, flexural strength, compressive strength, and drying shrinkage. The microscopic mechanisms of the mortar were analyzed using scanning electron microscopy and x‐ray diffraction. The below conclusions were drawn. First, the drying shrinkage and compressive strength of the mortar gradually increased with the increase of the activator dosage. Second, the drying shrinkage of the mortar initially decreased and then increased as increasing FA substitution, while the compressive strength decreased gradually in the early stage and then increased and decreased in the later stage. Lastly, by increasing the gypsum dosage, the drying shrinkage of the mortar was significantly reduced. However, the compressive strength gradually decreased. Besides, when adding 20% of FA and 2.4% of gypsum, it was found that ettringite, which underwent expansion, formed in the system. This not only reduced the drying shrinkage by 25.3% but also increased the compressive strength by 1.3%. Furthermore, our investigation has led to the development of a low‐shrinkage one‐part alkali‐activated slag and FA mortar, which not only facilitates the recycling of solid waste materials but also presents commendable environmental and economic advantages.

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Preparation and characterization of a new alkali-activated binder for superfine-tailings mine backfill

Sun

Zhao

Qiu

et al. 2022

Environ Sci Pollut Res

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Environmentally benign production of one-part alkali-activated slag with calcined oyster shell as an activator

Cited by 38 publications

References 42 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

Effect of fly ash and gypsum on drying shrinkage and mechanical properties of one‐part alkali‐activated slag mortar

Preparation and characterization of a new alkali-activated binder for superfine-tailings mine backfill

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