Full article: Development of high-performance …
To investigate the effect of heavyweight aggregate on the physico-mechanical properties of concrete, high-performance heavyweight concrete mixes using the coarse aggregates of magnetite (M), barite (B), goethite (G) and …
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Effects of iron oxides on the rheological properties of …
The cement used in this study is a commercial Portland cement (Lafarge North America Corp.) that satisfies Type I and Type II requirements set forth in ASTM American Society for Testing and Materials (ASTM) C-150 [8].The properties of Portland cement are presented in Table 1.Four iron oxides (and oxyhydroxides) were used for this study: magnetite, hematite, …
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Thermodynamic modeling of Portland cement without mineral additives
The paper deals with thermodynamic modeling of Portland cement hydration as a complex system, which describes the clinker dissolution, diffusion, and surface phenomena that occur on phase nuclei ...
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Working mechanism of calcium nitrate as an …
Precast concrete, cold weather concreting and the emerging technique of concrete additive manufacturing (AM) are applications in which the acceleration of cement hydration plays a critical role.
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Development of high- performance heavy density …
concrete, high-performance heavyweight concrete mixes using the coarse aggregates of magnetite (M), barite (B), goethite (G) and serpentine (S) were designed. Heavyweight concrete mixes can be proportioned using the American Concrete Institute method (ACI) of absolute volumes developed for normal concrete (Bunsell and Renard 2005).
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Hydration and phase evolution of blended cement …
According to reaction kinetics, goethite and hematite can only precipitate at elevated temperatures, such as 50 °C within months or 80 °C within days [81], ... Accelerated cement hydration during the first 24 h and the retarded hydration after 1 day in the presence of lithium is confirmed. From the NMR results, lithium mainly retards the ...
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Temperature Effects on Fe (OH)
Temperature is one of the most important factors affecting the hydration process and the crystallinity of cement pastes, and its effect on the gel phase cannot be ignored. The Fe(OH)3 phase is an indispensable gel phase in calcium sulfoaluminate cement, which significantly contributes to the desirable properties of CSA cement (especially ferric-rich …
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Mortar pore pressure prediction during the first hours of cement hydration
To summarize, cement hydration induces a volume reduction of evolving cement-based materials that is usually called shrinkage. ... Monocarboaluminate, Monosulfoaluminate, Ettringite, Hydrocalcite, Goethite, in addition to the minerals present in the cement (see section 3.1). 3.4. Stress and volume evolution.
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Effects of a red mud mineralogical composition versus …
Goethite is less reactive than Hematite during the cement hydration process because it is inherently less reactive and less soluble in the pore solution [5], [55]. The setting time and early-stages of strength development are not significantly affected by the presence of Goethite because unlike Hematite it cannot provide enough nucleation sites ...
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Study of mechanical, thermal, and nuclear radiation …
Barite-Goethite-Tourmaline concrete mix (BGT25), which contains barite ore as coarse aggregates, whereas the fine aggregates composed of 75% goethite and 25% tourmaline. 3. ... which is related to the loss and consumption of mixing water from concrete by heating and hydration. However, the compressive strength of BG concrete mix clearly ...
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Compressive strength of concrete made with barite, magnetite, goethite
The results indicated that, the compres- sive strengths of concrete mixes M1, M2 and M3 (containing magnetite aggregate) are significantly higher than those con- taining barite, goethite and ...
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Development of high-performance heavy density concrete using …
On the contrary, the concrete mixes made with goethite and serpentine coarse aggregate along with 10% SF, 20% FA and 30% GGBS did not satisfy the requirements of high-performance ... This leads to an increase in the compressive strength of concrete. Also, the hydration products possess a large specific volume than the unhydrated cement ...
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Mechanisms of cement hydration
The current state of knowledge of cement hydration mechanisms is reviewed, including the origin of the period of slow reaction in alite and cement, the nature of the acceleration period, the role of calcium sulfate in modifying the reaction rate of tricalcium aluminate, the interactions of silicates and aluminates, and the kinetics of the deceleration period.
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Selenite Sorption on Hydrated CEM-V/A Cement in the …
Numerous studies have reported RNs sorption behavior on cement hydration products.[10, 11] For instance, sorption of Se(IV, VI) oxyanions has attracted extensive ... magnetite-hematite coupling cement (C-M/H), and magnetite-goethite coupling cement (C-M/G) were produced with the aim of simulating the corroded steel interfaces in hydrated cement
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Synthesis, characterization and application of goethite …
Goethite (α-FeOOH) is a common oxy-hydroxide in natural environment and is formed as a weathering product of iron-bearing minerals. This mineral is the most important …
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Effect of PCs superplasticizers on the rheological properties …
The effect of polycarboxylate (PC) superplasticizers with different structure on the rheological properties and hydration process of slag-blended cement pastes with a slag content between 0 and 75% has been studied. Fluidizing properties of PCs admixtures are significantly higher in slag-blended cement with respect to non-blended Portland cement. Also, it has been …
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Experimental, analytical, and simulation studies of modified concrete …
The selected fine powdered boron carbide was found to be beneficial to the physic-mechanical properties of concrete as it enhances the cement hydration reaction due to the filler effect; thus, the ...
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Selenite Sorption on Hydrated CEM-V/A Cement in the …
Here, we combined wet chemistry methods, synchrotron- based X-ray techniques, and thermodynamic modelling to explore the redox interactions and non-redox sorption processes …
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Development of high-performance heavy density concrete using …
This leads to an increase in the compressive strength of concrete. Also, the hydration products possess a large specific volume than the unhydrated cement phases; ... On the contrary, the concrete with goethite and serpentine coarse aggregates with 10% SF, 20% FA and 30% GGBS did not satisfy the requirements of high-performance concrete ...
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Working mechanism of calcium nitrate as an …
Calcium nitrate is a frequently applied accelerator. Ca(NO 3) 2 was introduced as an accelerator for cement hydration during the 1980s 9 to replace chloride-containing accelerators such as calcium chloride ... In the …
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goethite in cement hydration
Goethite is a major constituent in ferruginous soils in a ... firstly carried out leaching experiments considering temperature effects to construct a solubility equilibrium model of cement hydrate.
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Development of high- performance heavy density …
In some mixes, compressive strengths were also tested up to 90 days upon replacing sand with the fine portions of magnetite, barite and goethite. The mixes containing magnetite along with …
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Study of the Course of Cement Hydration in the Presence of …
The microsilica additive showed an alkaline reaction in the water solution that can more actively react with cement hydration product on the surface of the metal particles. The …
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Long-term cement hydration studies with …
Cement hydration is a complex process, as cements normally consist . ... H instead of goethite as iron . rich phase at lower water cement ratios. In addition, a signi cant .
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Microstructure of Fe(OH)3 phase in hydration products of …
During hydration of plain cement portlandite and hydration products form below 450°С. Silica fume and fly ashes react with portlandite and form products decomposing above 620–640°С. View
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Using PHREEQC to model cement hydration
Using PHREEQC to model cement hydration ... A.A. Kamnev, et al., Investigation of the solution process of goethite (alphaFeOOH) in alkaline solutions, Russian J. Appl. Chem. (Zhurnal Prikladnoi Khimii) 59 (1986) 1560–1564. [146] Z. Yishin, A. Ruiyang, Y. Chen, Determination of the solubility of Fe2O3 in dilute aqueous solutions at 300oC and ...
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Microstructure and Key Properties of Phosphogypsum-Red …
The main mineral components of red mud are cancrinite, calcite, dicalcium silicate, tricalcium aluminate, hematite, goethite, boehmite, gibbsite, etc ... material gradually weakened, and this is mainly attributable to the reduction in red mud content. It is well known that cement hydration can generate large amounts of Ca(OH) 2, but ...
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Cement hydration
Hydration products. The products of the reaction between cement and water are termed "hydration products." In concrete (or mortar or other cementitious materials) there are typically four main types: Calcium silicate hydrate: this is the main reaction product and is the main source of concrete strength. It is often abbreviated, using cement chemists' notation, to "C-S-H," the …
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Full article: Development of high-performance heavy density concrete …
It is evident also from Fig. 2 that, the concrete mixes made from the coarse aggregates of goethite and containing 10% SF (G1) and 20% FA (G2) meet the requirements of dense concrete exceeding by about 2% and 1%, respectively; while, the density of concrete was declined by about 2% for the concrete matrix containing 30% GGBFS (G3) as a ...
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GEMS workshop 2020
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 …
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