Study on the treatment of BOF slag to replace fine aggregate in concrete

Ding, Yung‐Chin; Cheng, Ta‐Wui; Liu, Ping-Chun; Lee, Wei‐Hao

doi:10.1016/j.conbuildmat.2017.04.164

Cited by 66 publications

(30 citation statements)

References 23 publications

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“…Moreover, some drawbacks such as high drying shrinkage and volumetric instability compared to OPC concrete have been observed in alkali-activated concretes [15,16,17,18]. The utilisation of BOF slag as aggregates is limited by its excessive free calcium oxide (f-CaO), which easily reacts with water or CO 2 , forming Ca(OH) 2 or CaCO 3 and causing severe expansion and volume instability [19]. A 5–10% volume expansion was reported in [20], which resulted in forming some cracks and a reduction in mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

“…Pang et al [21] and Bodor et al [22] reported high efficiency of carbonation (temperature of 70–90 °C and 5–20 bar CO 2 pressure for 2 h) in controlling f-CaO in BOF slag; in addition, 15–50% improvement in the compressive strength was obtained when carbonated BOF aggregates were used. Other treatment methods for controlling f-CaO include weathering [23], attrition and chelation [19], and water quenching [24]. Weathering is the least preferable treatment because of its long duration (≈ 6 months), and the calcite film forms a coat around the BOF slag aggregates that weakens the cohesion between the aggregate and matrix, resulting in a reduction of the mechanical and durability properties [7].…”

Section: Introductionmentioning

confidence: 99%

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Using Carbonated BOF Slag Aggregates in Alkali-Activated Concretes

et al. 2019

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This experimental study aimed to develop alkali-activated concretes containing carbonated basic oxygen furnace (BOF) slag aggregates. In the first stage, the impacts of replacing normal aggregates with carbonated BOF slag aggregates in different alkali-activated concretes were determined by assessing mechanical properties (compressive and flexural strengths), morphology, thermogravimetric analyses (TGA), differential thermogravimetry (DTG) and the crystalline phases using X-ray diffraction analysis. Second, the developed plain alkali-activated concrete was reinforced by different fibre types and dosages to limit the negative impacts of the drying shrinkage and to improve strength. Therefore, the effects of using different fibre contents (1% and 1.5% in Vol.) and types (Polyvinyl alcohol [PVA], Polypropylene [PP], basalt, cellulose and indented short-length steel) on hardened state properties were evaluated. These evaluations were expressed in terms of the compressive and flexural strengths, ultrasonic pulse velocity, mass changes, drying shrinkage and efflorescence. Then, the impacts of aggressive conditions on the hardened properties of fibre-reinforced alkali-activated concretes were evaluated under carbonation, high temperature and freeze/thaw tests. The results showed that using carbonated BOF slag aggregates led to obtain higher strength than using normal aggregates in alkali activated concretes. Moreover, the maximum enhancement due to reinforcing the mixtures was recorded in alkali-activated concretes with steel fibres.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Using Carbonated BOF Slag Aggregates in Alkali-Activated Concretes

et al. 2019

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“…In the cement paste blended with slag, three structure reactions were involved: cement hydration, the pozzolanic reaction of slag, and hydration reaction of slag [27,28]. However, slag exhibits a pozzolanic reaction in the presence of calcium hydroxide (Ca(OH) 2 ) formed upon cement hydration [20].…”

Section: Microstructure Testsmentioning

confidence: 99%

Influences of Ultrafine Slag Slurry Prepared by Wet Ball Milling on the Properties of Concrete

Dai

et al. 2018

Advances in Materials Science and Engineering

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e application of ultrafine ground-granulated blast-furnace slag (GGBFS) in concrete becomes widely used for high performance and environmental sustainability. e form of ultrafine slag (UFS) used in concrete is powder for convenience of transport and store. Drying-grinding-drying processes are needed before the application for wet emission. is paper aims at exploring the performances of concrete blended with GGBFS in form of slurry. e ultrafine slag slurry (UFSS) was obtained by the process of grinding the original slag in a wet ball mill, which was mixed in concrete directly. e durations of grinding were 20 min, 40 min, and 60 min which were used to replace Portland cement with different percentages, namely, 20, 35, and 50, and were designed to compare cement with original slag concrete. e workability was investigated in terms of fluidity. Microstructure and pore structure were evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). e fluidity of concrete mixed with UFSS is deteriorated slightly. e microstructure and early strength were obviously improved with the grind duration extended.

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“…In China, it is estimated that the utilization rate of steel slag maintains at the level of 20%, which is not only four times less than that of the blast furnace slag, but also unmatched with approximately 100% utilization rate abroad [1][2][3]. However, the main reasons that limit the use of steel slag are classified into three categories: volume instability, poor grindability and low cementitious activity [4][5][6][7][8]. Compared with the other two, volume instability is the bottleneck that keeps the steel slag from large use among metallurgical solid waste.…”

Section: Introductionmentioning

confidence: 99%

Stabilization of free CaO in molten BOF slag by addition of silica at high temperature

Yin

Zhang

Wang

et al. 2018

Metall. Res. Technol.

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The unstable free CaO (f-CaO) has always been the bottleneck that limits the application of basic oxygen furnace (BOF) slag as a construction material. In this work, silica was regarded as the stabilization addition to make the f-CaO in molten BOF slag stabilized at high temperature. The influences of experimental conditions on the f-CaO stabilization were studied. The results show that the main influential factors on elimination rate of f-CaO are the ratio CaO/SiO2, reaction temperature and stabilization time. In this work setting conditions, with the ratio CaO/SiO2 less than 2.7, the reaction temperature under 1525 °C and the stabilization time over 10 min, the f-CaO content in the stabilized slag falls to the level of less than 3.00%, which can fully meet the Chinese national standard of steel slag powder used for cement and concrete. Additionally, the XRD results indicate that f-CaO is stabilized by silica in forming akermanite phase at high temperature. Moreover, the observation obtained from FESEM indicates that the undissolved lime and precipitated CaO changed into clustered CaO in the stabilized slag with its size ranging from 0.6 µm to 2.5 µm.

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Study on the treatment of BOF slag to replace fine aggregate in concrete

Cited by 66 publications

References 23 publications

Using Carbonated BOF Slag Aggregates in Alkali-Activated Concretes

Using Carbonated BOF Slag Aggregates in Alkali-Activated Concretes

Influences of Ultrafine Slag Slurry Prepared by Wet Ball Milling on the Properties of Concrete

Stabilization of free CaO in molten BOF slag by addition of silica at high temperature

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