CT scanning of internal crack mechanism and strength behavior of cement-fiber-tailings matrix composites

Cao, Shuai; Yilmaz, Erol; Yin, Zhen‐Yu; Xue, Gaili; Song, Weidong; Sun, Limin

doi:10.1016/j.cemconcomp.2020.103865

Cited by 118 publications

(28 citation statements)

References 86 publications

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“…The extraction of ore resources has promoted the progress of human civilization, providing critical raw materials for sustainable development and circular economy [1,2]. However, it is irrefutable that resource mining has also caused a series of complications, such as water and air pollution [3], geotechnical risks [4], environmental hazards [5], farmland occupation [6], and tailings dam failures [7]. Solid waste output is growing at an annual rate of over 1 billion tons [8].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Strength and Microstructural Characteristics of Mine Backfills Containing Fly Ash and Desulfurized Gypsum

2021

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The utilization of solid wastes (SWs) as a potential resource for backfilling is not only conducive to environmental protection but also reduces the surface storage of waste. Two types of SWs, including fly ash (FA) and desulfurized gypsum (DG), were used to prepare cementitious backfilling materials for underground mined-out areas. Ordinary Portland cement (OPC) was used as cement in mine backfill. To better investigate the feasibility of preparing backfill materials, some laboratory tests, such as uniaxial compressive strength (UCS), scanning electron microscopy (SEM), and energy dissipation theory, were conducted to explore both strength and microstructural properties of backfilling. Results have demonstrated that the main components of FA and DG in this study are oxides, with few toxic and heavy metal components. The ideal ratio of OPC:FA:DG is 1:6:2 and the corresponding UCS values are 2.5 and 4.2 MPa when the curing time are 7 days and 14 days, respectively. Moreover, the average UCS value of backfilling samples gradually decreased when the proportion of DG in the mixture increased. The main failure modes of various backfilling materials are tensile and shearing cracks. In addition, the corresponding relations among total input energy, dissipated energy and strain energy, and stress–strain curve were investigated. The spatial distribution of oxygen, aluminum, silicon, calcium, iron and magnesium elements, and hydration product are explored from the microstructure’s perspective. The findings of this study provide both invaluable information and industrial applications for the efficient management of solid waste, based on sustainable development and circular economy.

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Section: Introductionmentioning

confidence: 99%

Analysis of Strength and Microstructural Characteristics of Mine Backfills Containing Fly Ash and Desulfurized Gypsum

2021

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“…The results show that when the concentration of the slurry is 75 wt. %, with the increase of curing time at different times, the hydration reaction is gradually carried out, and the hydration products gradually fill the pores, which makes the strength of the paste backfill gradually increase [18].…”

Section: Effect Of Solid Content On the Microstructural Properties Of Cwtbmentioning

confidence: 99%

“…Furthermore, Rheology and geomechanical stability reflect the quality and performance of the cemented paste backfill [16]. Rheology is explained in terms of slump, the solid content, shear yield strength and the uniaxial compressive strength [16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Investigation on Mechanical Characteristics and Microstructure of Cemented Whole Tailings Backfill

2021

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A paste backfill performance can be primarily evaluated through the mechanical and physical characteristics of the components involved. In this study, the effects of solid components’ tailings, binders and waters contents on microstructural evolution and mechanical properties of uncemented whole tailings backfill (CWTB) mixtures were investigated. Different mixtures of ordinary Portland cement of 1, 3 and 5 wt. % and solid concentrations at 72 wt. %, 74 wt. % and 75 wt. % were selected and rheological test was conducted to define the slump fluidity and yield stress. The microstructure of the solid component before and after the preparation and chemical composition were analyzed by the Scanning electron microscope and XRD analysis, respectively. The results show that a positive correlation between yield stress and slump values of CWTB paste slurries, the decrease of flow consistence leads to the reduction of the water content on the CWTB mixtures and the flow resistance of the paste. With the highest solids content, unconfined compressive strength (UCS) of CWTB varies between 0.1–0.9 MPa. Increasing the solid content affects the porosity and improves the strength resistance of CWTB mixtures. The findings in this study can therefore lead us to a statement that CWTB chemical components seem to be an important factor in cemented paste backfill (CPB) design and mine operations.

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“…They reported that the internal pore structure of cemented backfill greatly influenced its failure mode and working performance. Cao et al [27] and Xue et al [28] prepared fiber fillers and scanned its internal structure through industrial CT and found the failures of backfill samples (i.e., tensile, shear, and tensile-shear mixed failures). They also found that the internal structure of the CTB has an improved effect on strength at a fiber output of 0.2 wt.%.…”

Section: Introductionmentioning

confidence: 99%

Investigation on Dynamical Mechanics, Energy Dissipation, and Microstructural Characteristics of Cemented Tailings Backfill under SHPB Tests

et al. 2021

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As mining depth increases, the backfill mining method is more and more widely used in underground mines. The dynamic load generated by the blasting can affect the stability of the cemented tailings backfill (CTB). The CTB samples were prepared to conduct a test of the split Hopkinson pressure bar (SHPB) to investigate the dynamic disturbance of CTB. The present paper discusses dynamical mechanics, energy dissipation, and microstructure analysis of CTB. Micro-computer tomography (micro-CT) scanning of CTB samples after the SHPB test was performed to analyze the evolution of internal cracks. The experimental results showed that when the average strain rate (ASR) increased from 30 to 98 s−1, the dynamic uniaxial compression strength (DUCS) of the CTB showed a trend of first increasing and decreasing with the increase in ASR. The dynamic stress–strain pre-peak curve of CTB directly enters the linear elastic stage. As ASR increases, the absorbed energy of the CTB shows a trend of first increasing and then decreasing. Moreover, according to the micro-CT scanning results, the crack area of CTB accounts for about 16% of the sample near the incident bar and about 1% near the transmitted bar. The crack area ratio is exponentially related to the specimen height. These findings can provide reasonable dynamical CTB strength data selection for underground pillar mining.

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CT scanning of internal crack mechanism and strength behavior of cement-fiber-tailings matrix composites

Cited by 118 publications

References 86 publications

Analysis of Strength and Microstructural Characteristics of Mine Backfills Containing Fly Ash and Desulfurized Gypsum

Analysis of Strength and Microstructural Characteristics of Mine Backfills Containing Fly Ash and Desulfurized Gypsum

Investigation on Mechanical Characteristics and Microstructure of Cemented Whole Tailings Backfill

Investigation on Dynamical Mechanics, Energy Dissipation, and Microstructural Characteristics of Cemented Tailings Backfill under SHPB Tests

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