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Effect of Aging on Chemical and Rheological Properties of Bitumen …

Engineering performance of asphalt pavement highly depends on the properties of bitumen, the bonding material to glue aggregates and fillers together. During the service period, bitumen is exposed to sunlight, oxygen and vehicle loading which in turn leads to aging and degradation. A comprehensive understanding of the aging mechanism of bitumen is of critical importance to …

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Impact of aging on the hydration of tricalcium aluminate (C3A)/gypsum

The presence of residual C 3 A can be further associated with its higher content in the original mixtures of the M1010 series, but also with the overdosed gypsum content used, which has been found ...

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Jets of three-phase power-law fluids and jet mixing in gypsum

Section 2 provides the original experimental data on the material rheology. Section 3 describes the problem formulation for jets of the three-phase power-law fluids. Section 4 describes the invariant-based coordinate transformation used to develop the novel numerical method proposed in this work. Section 5 discusses the results for straight jets issued into the …

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Effect of Phosphoric Acid on the Preparation of α-Hemihydrate Gypsum

Abstract. The effects of phosphoric acid (H 3 PO 4) in pressurized aqueous solution on the dehydration of CaSO 4 ·2H 2 O to form α-hemihydrate gypsum (α-HH) phase and the regulation of crystal shape were studied in this paper in order to provide guidance for the low-cost and high-value utilization of phosphogypsum. The results showed that H 3 PO 4 can significantly …

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Fire performance of gypsum-sheathed cold-formed steel walls …

Aging had a negligible effect on the insulation performance of LBR-FGP boards, while it enhanced the insulation performance of LBR-GP boards. The improvement was attributed to stress relief between gypsum crystals during dehydration and recrystallization, resulting in reduced cracking and improved insulation.

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Effects of various gypsum on early-age hydration behavior of …

Incorporation of natural gypsum (NG) to MOCP reduces its nucleation rate and growth rate, while an appropriate amount of flue gas desulfurization gypsum can provide …

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Phase evolution and mechanical performance of an ettringite …

Note that there was an amorphous fraction (ca. 25 wt%) in the aged binder, which is attributed to a C-(A-)S-H and aluminum hydroxide gel, and low-crystalline monosulfate. Fig. 3 shows the degree of hydration of individual phases in LS (i.e., C 12 A 7, Q-phase, γ-C 2 S, and MgO) and gypsum, obtained from Q-XRD analysis.

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Preparation of α-High Strength Gypsum from Flue Gas …

The effects of salt solution recycling on the transition of α-HH from FGD gypsum were investigated by a comparison with that in laboratory scale, focusing on the dehydration rate of FGD gypsum ...

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Investigation of the impurity effect on the kinetics of thermal

In this work, samples of natural gypsum from various locations of various chemical and phase compositions were studied, and the effect of a controlled amount of added crystalline modifier on the thermal properties of pure gypsum was investigated.The results of this study do not only expand knowledge about the basic mechanisms in natural gypsum ...

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Effects of various gypsum on early-age hydration behavior of …

to be the preferred hydration phase with significant strength gain due to its good lling and interconnection properties. However, in a humid environment, 5-phase and 3-phase are easily decomposed into Mg(OH) 2, and unreacted MgO will also be converted into Mg(OH) 2, which will cause cracking and performance degradation of sample [10, 12]. To ...

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New insight into the phase changes of gypsum

However, due to the increasing importance of gypsum recalcination (connected with the planned closure of thermal power plants resulting in a lack of FGD gypsum) and new …

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THE EFFECT OF GYPSUM PHASE COMPONENTS ON …

phase can variably be altered which consequently affects the rheokinetics of the cement paste. Currently, the effect of the available amount of hemihydrate and natural gypsum in the cement sulphate phase, on both the hydration and rheology of ordinary Portland cements (OPC), are not well-understood.

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Numerical investigation of gypsum board calcination under …

As gypsum boards are widely used in building construction, fires leave fire patterns on the gypsum board. Currently, fire investigators identify fire patterns by visible observation or through depth measurements of materials affected by the fire [1].This analysis demands the coupling of the physical laws of fire dynamics with the investigator's inference regarding the …

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Effect of gypsum content in cement on its adaptability to alkali …

The effects of three different curing temperatures (0°C, 20°C and 40°C) on cement setting times and performance were thus examined. ... both the CH and amorphous phase contents increased and then decreased with an increase in gypsum content. The amorphous phase content in OPC_97 + 3 was the highest among all the samples after curing at these ...

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Effects of various gypsum on early-age hydration behavior of …

This work investigated the effect of gypsum on the early-ages hydration progress of MOC systems by isothermal calorimetry and BNG model. The following conclusions can be …

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Effect of composite ratio of composite crystal modifiers on the

Some researchers enhanced the property of calcined gypsum by adding some additives, such as quaternary phase [18], pregelatinized starch [19], CaO [20], jute fibre bundle [21], etc. Hao [20] innovatively proposed the introduction of crystal modifier CaO to improve its property. It is well known that the crystal modifier plays an important role in control of the …

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Effect of superplasticizers on the properties of latex modified gypsum

The results indicate that the presence of cement as an additive could eliminate the weak points of construction gypsum without any negative side effect. The study was supported by aging ...

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Preparation of α-hemihydrate gypsum from phosphogypsum in …

The industrial application of PG is mainly focused on building gypsum (β-CaSO 4 ·0.5H 2 O) [5], α-hemihydrate gypsum (α-CaSO 4 ·0.5H 2 O, α-HH) [6], [7], cement retarder [8], sulfuric acid co-production cement [9], soil conditioner [10] and so on. Among which, the preparation of α-HH using PG is one of the most profitable approaches because α-HH is a …

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The effect of gypsum on the hydration of alite–belite–ferrite phase …

After the induction period, the behavior changes and gypsum enhance the C 3 S hydration [6,8,18,19,[51][52][53][54][55] [56] [57]; see Fig. 4. Yamashita et al. [58] have observed that increasing ...

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Effect of 800 °C/10,000 h aging-induced μ phase on plasticity in …

As the aging time increases, the size and area fraction of the μ phase initially increase, stabilizing after 2000 h of aging. Specifically, the μ phase maintains stable dimensions, with a length, width, and area fraction of approximately 1.35 μm, 0.55 μm, and 2.85 %, respectively.

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Artificial aging of gypsum binder in terms of thermodynamics

The largest increase occurs in 3 days of aging at the relative humidity of 80%. The studied thermodynamic analysis of the process has showed that the most significant change of …

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Preparation of α-High Strength Gypsum from Flue Gas

The effects of aging time, aging temperature, MBA addition and pH on the morphology of the synthesized CSD after hydration are investigated. 3.1.1 The effect of aging time on the synthesized crystals Figs.2(b-e) show SEM images of the synthesized crystals for different aging time under 3 g of MBA, 4 of pH, and 80 ℃ of aging temperature. With the

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Effects of microencapsulated phase change materials on the …

Microencapsulated phase change materials (MePCMs) were fabricated via sol–gel synthesis, with nano-SiO 2 acting as shell, lauric acid (LA) and myristic acid (MA) binary eutectic mixture as core materials, and then MePCMs were incorporated in gypsum. The thermal performances of LA-MA@nano-SiO 2 MePCM as well as MePCM based gypsum board were …

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Effect of Mechanical Activation Procedure on the Phase

phase composition of gypsum (dihydrate) with the aim of producing a partially dehydrated gypsum binder similar to incompletely fired binders [12]. EXPERIMENTAL We used natural gypsum from the Baskunchak deposit (Astrakhan oblast). To reduce the effect of impurities, we selected the purest CaSO 4 · 2H 2 O samples (98.3+% purity).

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Improvement of the Hydration Kinetics of High Ferrite

Request PDF | On Nov 4, 2021, Kechang Zhang and others published Improvement of the Hydration Kinetics of High Ferrite Cement: Synergic Effect of Gypsum and C 3 S–C 4 AF Systems | Find, read and ...

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Impact of aging on the hydration of tricalcium aluminate …

Due to the high reaction potential of cement and water, premature hydration can occur after unintentional exposure to moisture. Model binary mixtures of C3A and gypsum stored at 90% …

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Impact of accelerated climatic aging on the behavior of gypsum …

Early on in the development phase of laboratory material, the choice of the basic components of the composite is often based on the literature and on economic considerations. ... The gypsum plaster used is a quick-setting ... the effect of accelerated aging on the thermal and mechanical properties of two plaster and cereal straw composites was ...

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Preparation of α-High Strength Gypsum from Flue Gas …

The synthesis of α-calcium sulfate hemihydrate (α-CSH) from flue gas desulfurization (FGD) gypsum is a good way to realize the comprehensive utilization of FGD gypsum. To obtain α-CSH with the satisfactory performances, a facile hydrothermal-aging pretreatment process for FGD gypsum raw materials was proposed, where FGD gypsum was …

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Changes in the Strength Properties and Phase Transition of …

Based on the course of the DSC curves for the gypsum, gypsum with aerogel, gypsum with polymer, and gypsum with microspheres, it was found that transitions that are characteristic for …

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Impact of accelerated climatic aging on the behavior of …

Freezing-thawing and wetting-drying accelerated aging tests are considered to simulate outdoor conditions. Two straw-gypsum plaster composites were designed. Long-term durability under …

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