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Cement hydration is crucial for the strength development of cement-based materials; however, the mechanism that underlies this complex reaction remains poorly understood …
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Abstract. Dodecylamine (DDA) and sodium oleate (OL) are commonly used collectors in the reverse flotation and the direct flotation of goethite. However, the flotation mechanisms …
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The cement hydration kinetics is slow during the first 10 h, and then it accelerates up to 20 h, reaching 47% of hydration at 24 h. The degree of hydration is essential for the study because it shows when the maximum water consumption occurs. Table 2 summarizes the effect of admixtures on hydration kinetics. Table 2.
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Goethite varies in colour from yellow-brown to red. It is composed of about 80 to 90 percent Fe 2 O 3 and approximately 10 percent water. When dehydrated, goethite forms hematite; upon hydration, goethite becomes limonite. For detailed physical properties, see oxide mineral (table). Goethite, a widespread iron oxide mineral [α-FeO (OH)] and ...
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In this study, the first-principles density functional theory calculations were used to reveal the role of the hydration of the goethite surface and its effects on flotation reagents from a microscopic perspective. The calculation results showed that DDA was adsorbed on the surface of goethite by hydrogen bonds in the absence of hydration.
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In GEMS modeling, thermodynamic calculations of th e. mass balance in Portland cement clinker are normalized to 100 grams of weight. Therefore, 100 g of. Portland cement contain a pproxim ately 61 ...
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The Chemical reaction that takes place between cement and water is called as hydration of cement. This reacion is exothermic in nature, due to which considerable amount of heat is released during hydration of cement. This is called as 'heat of hydration'. The hydration of cement is not a sudden process. This reaction is faster in …
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After that, a designed mix which comprised barite/goethite aggregates plus fine-powdered boron carbide additive, was proposed to improve the overall radiation …
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Introduction. This paper reviews our understanding of the kinetics and mechanisms of cement hydration. It follows closely from papers written for the two …
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The Calcium Silicate Hydrate (C-S-H) nucleation is a crucial step during cement hydration and determines to a great extent the rheology, microstructure, and properties of the cement paste. Recent ...
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In the second stage (0.7–5 ns), Ca ions switch between Structures 1 and 2, while Structure 3 begins to appear. In the third stage (5–20 ns), most of the dissolving Ca ions exist as Structure 2 ...
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Nature Communications - Despite being crucial for elucidating the cement hydration mechanism, the initial hydration stage is poorly understood. Here, authors …
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Single file - hydration of Portland cement Hydration of a Portland cement The example will show the principle possibility to apply GEMS to simulate cement hydration. A cement composition from literature is used. hydration with w/c = 0.50 at 20°C is assumed (other assumptions are possible). 3
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Twin formation in hematite during dehydration of goethite. Original Paper. Published: 29 July 2016. Volume 43, pages 749–757, ( 2016 ) Cite this article. Download …
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CemGEMS (. https://cemgems.app) is a freeto- -use web app developed to meet this need, i.e. to assist cement chemists, students and industrial engineers in easily performing and visualizing thermodynamic simulations of hydration of cementitious materials at temperatures 0-99 °C and pressures 1-100 bar.
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PXCT data shows that C 4 AF hydrates little up to 93 h. This is likely due to the low w/c ratio in the scanned volume and its slow hydration rate. b Volumes and cumulative volumes for the ...
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Hydration of C 3 A. As C 3 A is the most reactive phase in cement, its role in (very) early hydration is important and concerns both mechanical properties as well as rheological performances. In the absence of sulfates, C 3 A reacts quickly with water and leads to a rapid and unintended setting called "flash set.".
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Dodecylamine (DDA) and sodium oleate (OL) are commonly used collectors in the reverse flotation and the direct flotation of goethite. However, the flotation mechanisms of DDA and OL on the goethite surface remain unclear. In this study, the first-principles density functional theory calculations were used to reveal the role of the hydration of the …
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Computer modelling techniques were used to elucidate the hydration behaviour of three iron (hydr)oxide minerals at the atomic level: white rust, goethite and hematite. A potential model was first adapted and tested against the bulk structures and properties of eight different iron oxides, oxyhydroxides and hydroxides, followed by …
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Color: Goethite exhibits a range of colors, including yellow-brown, reddish-brown, and dark brown. The color is influenced by impurities, hydration, and the presence of other minerals associated with it. Luster: Goethite typically has a dull or earthy luster, often appearing somewhat matte rather than shiny. This luster is a result of its fine ...
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Unless the cement is very finely ground and reground with excess water to regularly expose a fresh surface, it cannot be fully hydrated in a year or more. We can divide the process of hydration of cement into 5 phases, …
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Ali Zaoui. Full Professeur-Exceptional Class 2, Director of LGCgE Laboratory. Director of International Master. Verified email at univ-lille.fr - Homepage. Geo-materials and other materials Naomaterials - Materials for Civil engineering (concrete-minerals-clays-geopolymers) and envi. Title.
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With the continuous development of nuclear technology, it is necessary to urgently solve the nuclear safety problem. γ-rays have a strong penetrating power. The γ-ray-shielding performance of ordinary concrete prepared with natural sand is weak and cannot meet the practical application of engineering. The γ-ray shielding performance of …
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Similarly, a fundamental approach to understanding cement hydration would involve breaking the problem down to the study of the kinetics. Mechanisms of C 3 S or alite hydration. The rates of hydration of (triclinic) C 3 S, alite, and even PC have long been observed to vary with time by orders of magnitude in a complicated, nonmonotonic …
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goethite promotes formation of more goethite via Fe(II)−goethite electron transfer and template-directed nucleation and growth. We further hypothesize that …
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In a study of one year curing of CSA-cement with limestone, Ma et al. [ 13] used isothermal calorimetry, XRD, TGA and MIP, but calorimetry. was only used for the rst 48 h of hydration. A similar ...
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It should be noted that the shape of goethite is similar to that of gypsum [6, 23], and thus the addition of goethite in cement can cause problem similar to the false set. As shown in Fig. 3 ...
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tion of gibbsite (peak = 275 ° C) and goethite decom- ... the cement hydration, even with the dilution effect caused. by an increase in red mud content. Therefore, it can be.
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The density of fresh and hardened concrete made of magnetite, barite, goethite and serpentine is summarized in Table 5 and graphically represented in Fig. 2. To call the concrete as a high density concrete, it must have unit weight more than 2600 kg/m 3 as stated in TS EN 206-1 .
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The presence of hematite may reflect the existence of goethite minerals as well, which also has a subsequential temperature transformation of α-FeOOH ... For cement hydration kinetics, pastes were produced with 50 g of powder and a water/binder (w/b) ratio of 0.60. The mixtures were prepared external in a mixer frequency speed …
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