Strength development and microstructure characteristics of artificial concrete pillar considering fiber type and content effects

Cao, Shuai; Zheng, Di; Yilmaz, Erol; Yin, Zhen‐Yu; Xue, Gaili; Yang, FuDou

doi:10.1016/j.conbuildmat.2020.119408

Cited by 66 publications

(14 citation statements)

References 61 publications

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“…They can also be prepared concrete additives, backfilling, and construction materials [25,26]. However, tailings containing toxic elements or heavy metal ions cannot be used for filling underground voids according to the related environmental protection standards [27][28][29]. Thus, exploring the feasibility of using FA and DG to prepare mine backfilling is the main purpose of this study.…”

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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“…It can be seen that there are initial holes in CTB. A pseudo color-enhancing algorithm was used to process the micro-CT slice images to facilitate image analysis [40,41]. Figure 10 shows that the part of CTB wherein the stress wave acts first (Z = 40 mm) had partly been spalled and had some cracks and micro-cracks.…”

Section: Failure Modes Of Ctb Specimens Analysismentioning

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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“…The main use of tailings is to prepare filling materials and building materials, especially coarse-grained iron tailings can be used as an aggregate to prepare filling materials and concrete, iron tailings can be used as a kind of machine-made aggregate, and the performance of filling materials and concrete is good (Lv et al, 2019;Qi and Fourie, 2019;Protasio et al, 2020;Karthikeyan et al, 2021;Leong, 2021). Some tailings are used to prepare the concrete of mine pillars; the concrete has good mechanical properties by means of fiber reinforcement (Cao et al, 2020;Cao et al, 2021a;Cao et al, 2021b). However, with the continuous development of mineral processing technology, tailings become finer and finer, and the fine-grained tailings below 75 μm can reach more than 80% (Wu et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Effect of Iron Tailings and Slag Powders on Workability and Mechanical Properties of Concrete

Shen

Liu

et al. 2021

Front. Mater.

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Tailings are one of the largest solid wastes in stock at present. In order to improve the comprehensive utilization rate of tailings, especially to solve the problems of fine-grained tailings treatment, the concrete composite admixture was prepared by using iron tailings powder and slag powder. In order to study the influence of iron tailings powder on the workability and long-term mechanical properties of concrete, C30 and C50 concrete with different iron tailings powder dosages were prepared, and the slump, expansion, flexural strength, splitting tensile strength, and compressive strength of concrete at different ages were tested. The results showed that the proper addition of iron tailing powder is beneficial to the working performance of concrete and can effectively reduce the time-loss of concrete fluidity. When the content of iron tailings powder in the composite admixture is 50%, the 1080d long age strength of C30 and C50 concrete can reach 50.3 and 80.7 MPa. Based on the 28d compressive strength, the relative strength-age prediction model of iron tailings powder concrete was established. The calculation and experimental results show that the model can accurately predict the compressive strength of micro-powder concrete of iron tailings at long age, and the error rate is less than 1%. The results lay a theoretical foundation for the utilization of iron tailings in concrete.

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Strength development and microstructure characteristics of artificial concrete pillar considering fiber type and content effects

Cited by 66 publications

References 61 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 Dynamical Mechanics, Energy Dissipation, and Microstructural Characteristics of Cemented Tailings Backfill under SHPB Tests

Effect of Iron Tailings and Slag Powders on Workability and Mechanical Properties of Concrete

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