Research on the Thermal Conductivity and Water Resistance of Foamed Phosphogypsum

CaO and MgO are both reported as effective activators for blast furnace slag. However, the synergistic effect of these two components on the mechanical properties of alkali-activated blast furnace slag remains unclear. In this study, the flexural and compressive strengths of alkali-activated blast furnace slag powder with MgO and CaO range from 0% to 30% by the mass ratio of alkali-activated blast furnace slag powder are investigated. Moreover, the dry shrinkage rate of alkali-activated blast furnace slag powder is measured. One percent refractory fibers by volume of binder materials are added in the alkali-activated blast furnace slag. Some refractory fibers are treated with water flushing, meanwhile, some refractory fibers are directly used without any treatment. Finally, the scanning electron microscope, the thermogravimetric analysis curves and the XRD diffraction spectrums are obtained to reflect the inner mechanism of the alkali-activated blast furnace slag powder’s mechanical properties. The water-binder ratios of the alkali-activated blast furnace slag powder are 0.35 and 0.42. The curing ages are 3 d, 7 d and 28 d. The measuring temperature for the specimens ranges from 20 °C to 800 °C. Results show that the flexural and compressive strengths increase with the increased curing age, the decreased water-binder ratio and the addition of refractory fibers. The water-treated refractory fibers can improve the mechanical strengths. The mechanical strengths increase in the form of a quadratic function with the mass ratio of MgO and CaO, when the curing age is 3 d, the increasing effect is the most obvious. A higher water-binder ratio leads to an increasing the drying shrinkage rate. The activated blast furnace slag powder with CaO shows a higher drying shrinkage rate. The mechanical strengths decrease with the increasing testing temperature.

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“…Specimens are kept in these temperatures for 4 h before testing. The experimental details can be found in Feng’s research [ 34 ].…”

Section: Methodsmentioning

confidence: 99%

The Influence of CaO and MgO on the Mechanical Properties of Alkali-Activated Blast Furnace Slag Powder

et al. 2022

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“…Although the main structure is gypsum (CaSO 4 .2H 2 O), PG has a complex and changeable structure with phosphate rock-based radionuclides, rare earth elements, process residues such as phosphorus, sulfate, fluoride, and heavy metals. According to the stoichiometry, 5 tons of PG is generated per ton of phosphoric acid, and the annual accumulation rate has reached up to 300 Mtons (Feng et al, 2021;Yang et al, 2016;Wang et al, 2021).…”

Section: Phosphogypsum As a Challenge For Phosphate Fertilizer Industrymentioning

confidence: 99%

Industrial Waste Management: Economical Benefits of the Resource Utilization of Phosphogypsum

Avşar¹,

Gezerman²

2022

ijim

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There are many publications in the literature on the reuse of waste gypsum in material production. In this study, in which the analysis of these existing publications is made through the determinations, the data examined are limited to the article and these are not included. However, to understand the general framework of the research in this field better, a few of these in the related literature are given below as examples. It is seen that industrial waste gypsum, which is a type of waste gypsum, has been examined more. Phosphogypsum, which is included in this waste group, reduces the water requirement for adjusting the cement consistency by adding phosphogypsum in cement production. As a result of the addition of phosphogypsum in wall element production, it was determined that the addition of phosphogypsum caused a decrease in mechanical strength, a decrease in unit weight and an increase in water requirement. It has been concluded that the addition of 15% phosphogypsum in soil stabilization of phosphogypsum, which is in the chemical waste class, causes an increase in water demand and pressure strength. In addition, 5.4% gypsum board waste with recycling potential is generated in the production of building elements made with waste gypsum boards formed at a construction site.

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“…Phosphogypsum (PG) is a by-product of solid waste produced from the production of wet-process phosphoric acid; for instance, one ton of phosphoric acid produces 5 tons of phosphogypsum [1,2]. PG is mainly composed of calcium sulfate dihydrate (CaSO 4 •2H 2 O), accounting for more than 90% of its structure.…”

Section: Introductionmentioning

confidence: 99%

“…In order to use PG to prepare lightweight building materials, Wang et al [20] added 25% Portland cement, 10-20% fly ash, 10% ground slag, 6% hydrated lime and 60% foam into PG to prepare lightweight building materials with a compressive strength of 1.7 MPa, bulk density of 521.7 kg/m 3 and thermal conductivity of 0.0724 w/(m•k). Feng et al [1] studied the effects of foam volume and cement content on thermal conductivity, the water resistance coefficient and the mechanical strength of foamed phosphogypsum, and obtained the effect of the foam content for each performance. Cement can increase thermal conductivity, water resistance and mechanical strength.…”

Section: Introductionmentioning

confidence: 99%

Proportion and Performance Optimization of Lightweight Foamed Phosphogypsum Material Based on an Orthogonal Experiment

et al. 2022

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A lightweight foam phosphogypsum material (LFPM) was prepared by multi-factor orthogonal and optimization experiments. The effects of foam, quicklime, silica fume and cement on the mechanical and physical properties of this LFPM were studied. The orthogonal experimental results showed that the silica fume content exhibited the most significant effect on the strength of this material, and the cement content exhibited the most obvious influence on the softening coefficient. The comprehensive index analysis indicated that the LFPM with 8% foam, 3.5% quicklime, 3% silica fume and 15% cement was selected as the optimal proportion. The 28 d compressive strength and flexural strength were 3.15 and 0.97 MPa, respectively. The dry density was 809.1 kg/m3, and the 28 d softening coefficient was 0.628. The optimization experimental results showed that the strength and dry density of the sample increased first and then decreased with an increase in the foam stabilizer content. The strength and dry density increased, and water absorption decreased with increasing waterproof agent content.

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Research on the Thermal Conductivity and Water Resistance of Foamed Phosphogypsum

Cited by 16 publications

References 35 publications

The Influence of CaO and MgO on the Mechanical Properties of Alkali-Activated Blast Furnace Slag Powder

The Influence of CaO and MgO on the Mechanical Properties of Alkali-Activated Blast Furnace Slag Powder

Industrial Waste Management: Economical Benefits of the Resource Utilization of Phosphogypsum

Proportion and Performance Optimization of Lightweight Foamed Phosphogypsum Material Based on an Orthogonal Experiment

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