Utilization of original phosphogypsum as raw material for the preparation of self-leveling mortar

Yang, Lin; Zhang, Yunsheng; Yan, Yun

doi:10.1016/j.jclepro.2016.04.054

Cited by 173 publications

(57 citation statements)

References 25 publications

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“…Much of the research was to determine if the CPB mixture with a slump value over 170 mm could be successfully transported underground by backfill pumps [39][40][41]. Therefore, in this study, trial slump tests [9] were conducted to make sure that the slump values of the OCPB and TCPB mixtures were greater than 170 mm. The preparation of materials and the test process were in accordance with the standard test method for slump [42].…”

Section: Test Of Abrams Conementioning

confidence: 99%

“…The effective utilisation of PG as an industrial waste is closely related to the coordinated development of natural resources, environment, and economy. However, because of the physical and chemical characterisations of PG, strong acidity (pH < 3) and high moisture content, only about 15% of PG has been reused in different fields such as soil stabilisation amendments, agricultural fertilisers, as set controller in cement manufacture, and in building materials [8][9][10][11]. Recently, researchers [12][13][14] have applied PG in cemented paste backfill (CPB) for use in underground mine stopes, which has been approved as an economic, safe, and environmentally friendly technology.…”

Section: Introductionmentioning

confidence: 99%

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Utilisation of Water-Washing Pre-Treated Phosphogypsum for Cemented Paste Backfill

et al. 2019

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Recycling phosphogypsum (PG) for cemented paste backfill (CPB) has been widely used at phosphate mines in China. However, the impurities in PG prolong the setting time and reduce the uniaxial compressive strength (UCS), limiting the engineering application of PG. This paper aims to investigate the feasibility of treated PG (TPG) washed repeatedly using deionised water (DW) for CPB. A water-washing pre-experiment was first conducted to find the proportion with the least DW demand and the effects of water-washing on ordinary PG (OPG). Then, based on the PG:DW ratio obtained from the pre-experiment, the properties of the OPG-based CPB (OCPB) and TPG-based CPB (TCPB) were tested using slump tests, UCS tests, and microstructural analysis. The results show that (1) after 11 water-washings at the PG:DW ratio of 1:1.75, the pH of the supernatant (pH = 6.328) meets the requirements of Chinese standard GB 8978-1996. (2) Water-washing improves the particle gradation quality of PG and removes the soluble impurities adsorbed at the surface of PG crystals. (3) The initial slump values of TCPB are 0.19–1.15 cm higher than that of OCPB, furthermore, the diffusivity values of TCPB are better than the performance of OCPB, with 0.61–1.68 cm of superiority. (4) The UCS values of TCPB are up to 0.838 MPa, 1.953 MPa, and 2.531 MPa, after curing for 7, 14, and 28 days. These are 0.283 MPa, 0.823 MPa, and 0.881 MPa higher than that of OCPB, respectively. It can be concluded that water-washing pre-treatment greatly improves the workability and mechanical property of PG-based CPB. These results are of great value for creating a reliable and environmentally superior alternative for the recycling of PG and for safer mining production.

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Section: Test Of Abrams Conementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Utilisation of Water-Washing Pre-Treated Phosphogypsum for Cemented Paste Backfill

et al. 2019

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“…e SLM uses chemical admixtures, aluminous cement, and high volumes of powders, which increase the mortar costs [5]. Chemical admixtures and high volume of powders are used to modify the rheological properties of the paste [6].…”

Section: Introductionmentioning

confidence: 99%

“…us, the use of wastes in SLM preparation is a solution to decrease the cost of this material [5]. e use of wastes in SLM has already been studied to replace both cement and fine aggregates [7], like slate waste [3] and fly ash [8]; the addition of ground-granulated blast furnace slag [9]; use of original phosphogypsum as raw material [6] and as binder [10]; and use of construction and demolition wastes (CDWs) [11].…”

Section: Introductionmentioning

confidence: 99%

Fresh and Hardened Properties of Self‐Leveling Mortars with Porcelain and Red Ceramic Wastes

Pereira

Camarini

2018

Advances in Civil Engineering

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Self-leveling mortar (SLM) has several advantages when compared to the conventional mortar used in subfloors, especially when productivity is desired. In Brazil, the use of SLM is not still widespread related to conventional mortar. Few builders are using it in constructions. In the same way, the sustainable reuse of wastes in building materials is not so great, but it has grown, becoming increasingly important. In Brazil, a great amount of waste is generated by the manufacture of electrical porcelain insulators and red ceramic. These materials are formed mainly by amorphous silicates and aluminosilicates, which when added as cement replacement can generate pozzolanic reactions. The present study evaluated the feasibility of using such wastes to replace cement to make SLM. Mortars were studied in the fresh state (fluidity, segregation and/or bleeding, outflow rate, outflow time, and kinetics of temperature) and in the hardened state (compressive strength, flexural tensile strength, capillary water absorption, water penetration height, and air permeability). According to the results, the cement replacement by porcelain or ceramic in SLM diminishes the flow and increases the setting time. The compressive strength is higher than the minimum related to literature, and the low values of water absorption and permeability were reached with porcelain waste.

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“…PG is primarily composed of calcium sulfate dihydrate (90 wt.%, CSD), but also contains a small quantity of impurities such as fluorides, phosphates, residual acids and organic matters. [3,4] Recently, many researchers have devoted to the application of PG in Portland cement, [5] soil conditioner, [6] ammonium sulfate production, [7] self-leveling mortar, [8] DOI: 10.1002/crat.201700162 foam concrete, [9] carbon dioxide mineralization, [10] etc. Among them, producing alpha calcium sulfate hemihydrates (α-CSH) from PG is a cost-effective and promising way to recycle PG.…”

Section: Introductionmentioning

confidence: 99%

Morphology‐Controlled Preparation of α‐Calcium Sulfate Hemihydrate from Phosphogypsum by Semi‐Liquid Method

Chen

et al. 2017

Crystal Research and Technology

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Phosphogypsum (PG), a by-product of phosphoric acid industry, causes environmental issues. In this paper, PG was effectively transformed into alpha-calcium sulfate hemihydrate (ɑ-CSH) via a semi-liquid method. The phase evolution and the effects of different organic acids and pH values on crystal morphology of the α-CSH were investigated by SEM, XRD and EDS. The properties of the prepared α-CSH with different aspect ratio were also compared. The results indicate that PG can be successfully transformed into α-CSH by the semi-liquid method at 140°C for 3.0 h. The morphology of the produced α-CSH is significantly influenced by the concentrations of organic acid and pH value. α-CSH crystal with well-morphology is obtained under the condition of 0.1 wt.% maleic acid and pH = 7.0. The obtained α-CSH with uniform particle size has the aspect ratio of 1.2. The 2 h and 3 d bending/compressive strengths of the hardened paste prepared from the α-CSH reach 6.4/20.6 MPa and 10.5/43.7 MPa respectively, which are comparable to those of the commercial α-CSH. Moreover, the lower aspect ratio of ɑ-CSH results in more compact microstructure and higher mechanical strengths of the hardened paste.

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Utilization of original phosphogypsum as raw material for the preparation of self-leveling mortar

Cited by 173 publications

References 25 publications

Utilisation of Water-Washing Pre-Treated Phosphogypsum for Cemented Paste Backfill

Utilisation of Water-Washing Pre-Treated Phosphogypsum for Cemented Paste Backfill

Fresh and Hardened Properties of Self‐Leveling Mortars with Porcelain and Red Ceramic Wastes

Morphology‐Controlled Preparation of α‐Calcium Sulfate Hemihydrate from Phosphogypsum by Semi‐Liquid Method

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