Experimental Study on Microstructure and Erosion Mechanisms of Solid Waste Cemented Paste Backfill under the Combined Action of Dry–Wet Cycles and Sulphate Erosion

Li, Kexin; Li, Xilin; Du, Chuanyang; Xue, Haowen; Sun, Qi; Liu, Ling

doi:10.3390/ma15041484

Cited by 12 publications

(5 citation statements)

References 26 publications

(26 reference statements)

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“…According to previous results from our research group [ 17 ], the mix ratio was optimized considering the strength, the degree of collapse and the cost of the filling paste. The optimal ratio of the solid mass fraction was 70.32% and of the water mass fraction was 29.68%, and steel slag, oil shale residue and soda residue were 47.43%, 40.54% and 12.03% of the total solid mass, respectively.…”

Section: Methodsmentioning

confidence: 99%

Changes in the Strength and Leaching Characteristics of Steel Slag-Oil Shale Residue-Based Filling Paste in a Complex Erosive Environment

Lian

Meng

2023

Materials

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Our research group prepared a new filling paste consisting of steel slag–oil shale residue and no admixtures. It was used as the research object to explore the combined effect of chloride and dry–wet cycling-driven erosion on the long-term stability of a cemented filling paste made of total solid wastes. Macroscopic experiments and microscopic analyses methods were employed. The influence of solutions with different mass fractions of chloride salts and different cycling periods on the uniaxial compressive strength and toxicity of the steel slag–oil shale residue-based filling paste was studied, and the deterioration mechanisms of the steel slag–oil shale residue-based filling paste under combined erosion from chloride and dry–wet cycling were investigated. The test results showed that in the same cycling conditions, the strength of the steel slag-oil shale residue-based filling paste increased first with the increase in the mass fraction of the chloride solution and then decreased with the increase in the mass fraction of the chloride solution after reaching the peak value; the leached concentrations of heavy metal ions decreased with increasing chloride salt mass fraction. With an increase in the number of dry–wet cycles, the compressive strength of the specimens in the chloride salt solution with a mass fraction of 0 (pure water) first increases and then tends to be stable. The strength of samples in 5% and 10% chloride salt solutions increased first and then decreased with an increase in the number of dry–wet cycles. The leached concentrations of heavy metal ions from the samples in all three solutions first decreased and then stabilized. The prehydration products of the steel slag–oil shale residue-based filling paste were C-S-H gels, AFt and Friedel’s salt, and these increased with increasing chloride salt mass fraction and the number of dry–wet cycles. However, the hydration reactions of the samples in the 0% chloride solution nearly stopped in the later stages of cycling, and the samples in 5% and 10% chloride salt solutions developed local cracks due to the accumulation of hydration products. The results showed that the number of dry–wet cycles and the chloride salt mass fraction affected the strength and leaching characteristics of the steel slag–oil shale residue-based filling paste by changing the type and amount of erosion products. The test results provide a scientific basis for the promotion and application of backfilling pastes made from total solid wastes.

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Section: Methodsmentioning

confidence: 99%

Changes in the Strength and Leaching Characteristics of Steel Slag-Oil Shale Residue-Based Filling Paste in a Complex Erosive Environment

Lian

Meng

2023

Materials

Self Cite

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“…Past studies on the mechanical properties of CPB have focused on its strength and deformation behavior [44]. Uniaxial compressive strength (UCS) is a commonly used mechanical index, which directly reflects the hardening process of CPB [45][46][47][48]. In a UCS test, the CPB can generate, propagate, locate, and accumulate cracks, resulting in a series of stress-strain behaviors [49][50][51].…”

Section: Introductionmentioning

confidence: 99%

The Failure Mechanical Properties of Cemented Paste Backfill with Recycled Rubber

Yang

Wang

et al. 2023

Materials

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Understanding the mechanical properties and failure process of cemented paste backfill with recycled rubber (RCPB) is the foundation of backfill design in underground mining. In this study, physical and mechanical tests were conducted on RCPB to obtain its mechanical property parameters, such as its uniaxial compressive strength (UCS), toughness, and peak strain. The influence of the rubber dosage on the mechanical properties of RCPB was also analyzed. In addition, the deformation behavior, fracture development, and failure process of RCPB with different rubber contents were observed using the digital image correlation (DIC) technique. The experimental results suggested that, although the UCS of RCPB is reduced as more rubber is added, its toughness and ability to absorb energy is increased. Moreover, the impact resistance of RCPB is improved by this increased toughness. With the increase in the rubber content, the deformation corresponding to the plastic yield stage of RCPB increased, which resulted in better ductility and improved impact resistance. The failure of the RCPB specimens mainly showed an “X” shape. The results of this study help us to better understand the mechanical behavior of RCPB after backfilling underground.

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“…Macropores have a negative effect on the sulfate resistance durability of cellulose fiber concrete, while micropores and mesopores are favorable [14]. The dry-wet cycles significantly accelerated sulfate corrosion, and the concrete with fly ash performed better sulfate resistance than the concrete with ground granulated blast-furnace slag and silica fume [20,21]. In conclusion, the dry-wet cycle accelerated the performance degradation process of concrete under a sulfate environment, and the composition and replacement rate of mineral admixtures had complex effects on its corrosion resistance.…”

Section: Introductionmentioning

confidence: 99%

Dry–Wet Cyclic Sulfate Attack Mechanism of High-Volume Fly Ash Self-Compacting Concrete

Liu

Yang

et al. 2022

Sustainability

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High-volume fly ash replacing cement helps to improve the fluidity, volume stability, durability, and economy of self-compacting concrete (SCC). Sulfate attack is the most common form of the durability damage of hydraulic concrete; in particular, the performance degradation at the water level change position is more significant. Therefore, research on the influence effect and mechanism of fly ash on the durability is of great significance. In this paper, the change regularity of the SCC physical and mechanical properties with the fly ash replacement percentage and dry–wet cycles were studied by 60 dry–wet cycles of sulfate attack test. The 6 h electric flux, MIP, and SEM were used to study the performance degradation mechanism of SCC cured for 56 days, which had also been attacked by sulfate. The results show that the physical and mechanical properties of SCC increased first and then decreased with the dry–wet cycles of sulfate attack. After 10–15 cycles, the corresponding properties increased slightly, and then decreased gradually. When the fly ash content was 40%, the corrosion resistance coefficient, relative dynamic elastic modulus, and flexural strength retention were higher than those of the control specimen. However, when the fly ash content was 50%, they were close to the control and deteriorated obviously with the further addition of fly ash. For pore sizes in the range of 120–1000 nm, the porosity of SCC cured for 56 days was inversely proportional to the 6 h electric flux and the retention of mechanical properties, indicating that the porosity of the large pores is the decisive factor affecting the chloride ion permeability and corrosion resistance. The incorporation of fly ash in SCC can change the sulfate attack products and destruction mechanism. The sulfate attack damage of SCC with 40% of fly ash and the control specimen was dominated by ettringite crystallization and expansion, while those with a fly ash content of 50% and 60% had no obvious corrosion products, and the microstructures became looser. The appropriate fly ash replacement percentage could significantly improve the corrosion resistance of SCC.

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Experimental Study on Microstructure and Erosion Mechanisms of Solid Waste Cemented Paste Backfill under the Combined Action of Dry–Wet Cycles and Sulphate Erosion

Cited by 12 publications

References 26 publications

Changes in the Strength and Leaching Characteristics of Steel Slag-Oil Shale Residue-Based Filling Paste in a Complex Erosive Environment

Changes in the Strength and Leaching Characteristics of Steel Slag-Oil Shale Residue-Based Filling Paste in a Complex Erosive Environment

The Failure Mechanical Properties of Cemented Paste Backfill with Recycled Rubber

Dry–Wet Cyclic Sulfate Attack Mechanism of High-Volume Fly Ash Self-Compacting Concrete

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