Effects of Foreign Ions on Minerals of High Belite-Calcium Sulfoaluminate Cement

The influence of foreign ions doping on the property of belite - sulfoaluminate (BCSA) clinker with belite and calcium sulfo-aluminate as main minerals was investigated. The research on four foreign doping ions with P5+, B2+, Ba2+, and Zn2+was carried out. The mineral components were characterized by SEM, X-ray powder diffraction and Infrared. Some foreign ions entering into the lattice of β-C2S and during sintering at high temperature attained a high reactivity. The mechanism of the effect of these ions on stabilization and activation of minerals were clarified. Results revealed that P5+, Ba2+, and Zn2+could stabilize and activate β-C2S as well as enhance reactivity of, but no positive effect of ion B2+was observed. The sequence of influence of different ions on C2S is: Ba2+>P5+>Reference>Zn2+>B3+, and the sequence for was: P5+>Ba2+>Zn2+>Reference>B3+. Compared to the 28-d compressive strength of reference one, P5+, Ba2+, and Zn2+could enhance the strength by 15.6%, 8.9% and 26.5% respectively.

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Effect of Naphthalene-Based Superplasticizer and Polycarboxylic Acid Superplasticizer on the Properties of Sulfoaluminate Cement

Materials ◽

10.3390/ma14030662 ◽

2021 ◽

Vol 14 (3) ◽

pp. 662

Author(s):

Yonghua Wu ◽

Qiqi Li ◽

Guoxin Li ◽

Shiying Tang ◽

Mengdie Niu ◽

...

Keyword(s):

Compressive Strength ◽

Setting Time ◽

Hydration Products ◽

Polycarboxylic Acid ◽

X Ray Diffraction ◽

Calcium Sulfoaluminate Cement ◽

X Ray ◽

Initial Setting Time ◽

Calcium Sulfoaluminate ◽

Initial Setting

In order to study what the effect of superplasticizers on the setting time, fluidity and compressive strength of calcium sulfoaluminate cement (CSA) a naphthalene-based superplasticizer (BNS) and a polycarboxylic acid superplasticizer (PC) were selected to interact with CSA pastes and ye’elimite, respectively. X-ray diffraction (XRD), thermogravimetric (TG) analysis and scanning electron microscopy (SEM) analytical methods were used to investigate the class, amount and microstructure of the CSA pastes and ye’elimite pastes hydration products under the effect of the superplasticizers. The results showed that the addition of BNS can promote ettringite generation and thus improve the early compressive strength. As the addition of BNS increased from 0.8 wt% to 2.0 wt%, the initial setting time was prolonged 10 min, the final setting time was prolonged 7 min, the 5 min fluidity was improved from no fluidity to 220 mm. However, as the addition of PC increased from 0.08 wt% to 0.20 wt%, the setting time of the PC just changed within 3 min; the 5 min fluidity increased from 110 mm to 195 mm and no 15 min fluidity at all was observed. AS seen by SEM, it can be stated that generated ettringite under the addition of PC was layered and lacking bonding, and its morphology changed from rod-like to flake-like, leading to a decrease in early compressive strength.

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Strength Performance and Microstructure of Calcium Sulfoaluminate Cement-Stabilized Soft Soil

Sustainability ◽

10.3390/su13042295 ◽

2021 ◽

Vol 13 (4) ◽

pp. 2295

Author(s):

Hailong Liu ◽

Jiuye Zhao ◽

Yu Wang ◽

Nangai Yi ◽

Chunyi Cui

Keyword(s):

Soft Soil ◽

Hydration Product ◽

X Ray Diffraction ◽

Calcium Sulfoaluminate Cement ◽

Strength Performance ◽

X Ray ◽

Calcium Sulfoaluminate ◽

Stabilized Soil ◽

Calcium Silicates ◽

Hydrated Calcium

Calcium sulfoaluminate cement (CSA) was used to stabilize a type of marine soft soil in Dalian China. Unconfined compressive strength (UCS) of CSA-stabilized soil was tested and compared to ordinary Portland cement (OPC); meanwhile the influence of amounts of gypsum in CSA and cement contents in stabilized soils on the strength of stabilized soils were investigated. X-ray diffraction (XRD) tests were employed to detect generated hydration products, and scanning electron microscopy (SEM) was conducted to analyze microstructures of CSA-stabilized soils. The results showed that UCS of CSA-stabilized soils at 1, 3, and 28 d firstly increased and then decreased with contents of gypsum increasing from 0 to 40 wt.%, and CSA-stabilized soils exhibited the highest UCS when the content of gypsum equaled 25 wt.%. When the mixing amounts of OPC and CSA were the same, CSA-stabilized soils had a significantly higher early strength (1 and 3 d) than OPC. For CSA-stabilized soil with 0 wt.% gypsum, monosulfate (AFm) was detected as a major hydration product. As for CSA-stabilized soil with certain amounts of gypsum, the intensity of ettringite (Aft) was significantly higher than that in the sample hydrating without gypsum, but a tiny peak of AFm also could be detected in the sample with 15 wt.% gypsum at 28 d. Additionally, the intensity of AFt increased with the contents of gypsum increasing from 0 to 25 wt.%. When contents of gypsum increased from 25 to 40 wt.%, the intensity of AFt tended to decrease slightly, and residual gypsum could be detected in the sample with 40 wt.% gypsum at 28 d. In the microstructure of OPC-stabilized soils, hexagonal plate-shaped calcium hydroxide (CH) constituted skeleton structures, and clusters of hydrated calcium silicates (C-S-H) gel adhered to particles of soils. In the microstructure of CSA-stabilized soils, AFt constituted skeleton structures, and the crystalline sizes of ettringite increased with contents of gypsum increasing; meanwhile, clusters of the aluminum hydroxide (AH3) phase could be observed to adhere to particles of soils and strengthen the interaction.

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Properties of Calcium Sulfoaluminate Cement Mortar Modified by Hydroxyethyl Methyl Celluloses with Different Degrees of Substitution

Molecules ◽

10.3390/molecules26082136 ◽

2021 ◽

Vol 26 (8) ◽

pp. 2136

Author(s):

Shaokang Zhang ◽

Ru Wang ◽

Linglin Xu ◽

Andreas Hecker ◽

Horst-Michael Ludwig ◽

...

Keyword(s):

Compressive Strength ◽

Flexural Strength ◽

Bond Strength ◽

Cement Mortar ◽

Retention Rate ◽

Methyl Cellulose ◽

Tensile Bond Strength ◽

Calcium Sulfoaluminate Cement ◽

Calcium Sulfoaluminate ◽

Cement Mortars

This paper studies the influence of hydroxyethyl methyl cellulose (HEMC) on the properties of calcium sulfoaluminate (CSA) cement mortar. In order to explore the applicability of different HEMCs in CSA cement mortars, HEMCs with higher and lower molar substitution (MS)/degree of substitution (DS) and polyacrylamide (PAAm) modification were used. At the same time, two kinds of CSA cements with different contents of ye’elimite were selected. Properties of cement mortar in fresh and hardened states were investigated, including the fluidity, consistency and water-retention rate of fresh mortar and the compressive strength, flexural strength, tensile bond strength and dry shrinkage rate of hardened mortar. The porosity and pore size distribution were also analyzed by mercury intrusion porosimetry (MIP). Results show that HEMCs improve the fresh state properties and tensile bond strength of both types of CSA cement mortars. However, the compressive strength of CSA cement mortars is greatly decreased by the addition of HEMCs, and the flexural strength is decreased slightly. The MIP measurement shows that HEMCs increase the amount of micron-level pores and the porosity. The HEMCs with different MS/DS have different effects on the improvement of tensile bond strength in different CSA cement mortars. PAAm modification can improve the tensile bond strength of HEMC-modified CSA cement mortar.

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Color tunable Ca8ZnM(PO4)7 (M = Lu/Tb, Lu/Eu, Tb/Eu) phosphors: luminescence, energy transfer and thermal stability studies for n-UV white LEDs

Dalton Transactions ◽

10.1039/d1dt01901e ◽

2021 ◽

Author(s):

Jing Yan ◽

Chunyan Jiang ◽

Yulun Xian ◽

Jianbang Zhou ◽

Hong Li ◽

...

Keyword(s):

Thermal Stability ◽

Energy Transfer ◽

High Temperature ◽

Solid State ◽

Powder Diffraction ◽

Stability Studies ◽

X Ray ◽

White Leds ◽

Color Tunable ◽

Xrd Patterns

A series of Tb3+- and Eu3+-doped Ca8ZnLu(PO4)7 (CZLP:Tb3+ and CZLP:Eu3+) as well as Ca8ZnTb(PO4)7:Eu3+ (CZTP:Eu3+) phosphors have been prepared via the traditional high-temperature solid-state reaction. X-ray powder diffraction (XRD) patterns...

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Method for the Accelerated Testing of the Durability of a Construction Binder using the Arrhenius Approach

Slovak Journal of Civil Engineering ◽

10.1515/sjce-2016-0004 ◽

2016 ◽

Vol 24 (1) ◽

pp. 24-33 ◽

Cited By ~ 2

Author(s):

Marcela Fridrichová ◽

Karel Dvořák ◽

Dominik Gazdič

Keyword(s):

Compressive Strength ◽

High Temperature ◽

Time Budget ◽

Test Subject ◽

Fluidised Bed ◽

Good Correspondence ◽

Chemical Corrosion ◽

Chemical Reaction Kinetics ◽

X Ray

AbstractThe single most reliable indicator of a material’s durability is its performance in long-term tests, which cannot always be carried out due to a limited time budget. The second option is to perform some kind of accelerated durability tests. The aim of the work described in this article was to develop a method for the accelerated durability testing of binders. It was decided that the Arrhenius equation approach and the theory of chemical reaction kinetics would be applied in this case. The degradation process has been simplified to a single quantifiable parameter, which became compressive strength. A model hydraulic binder based on fluidised bed combustion ash (FBC ash) was chosen as the test subject for the development of the method. The model binder and its hydration products were tested by high-temperature X-ray diffraction analysis. The main hydration product of this binder was ettringite. Due to the thermodynamic instability of this mineral, it was possible to verify the proposed method via long term testing. In order to accelerate the chemical reactions in the binder, four combinations of two temperatures (65 and 85°C) and two different relative humidities (14 and 100%) were used. The upper temperature limit was chosen because of the results of the high-temperature x-ray testing of the ettringite’s decomposition. The calculation formulae for the accelerated durability tests were derived on the basis of data regarding the decrease in compressive strength under the conditions imposed by the four above-mentioned combinations. The mineralogical composition of the binder after degradation was also described. The final degradation product was gypsum under dry conditions and monosulphate under wet conditions. The validity of the method and formula was subsequently verified by means of long-term testing. A very good correspondence between the calculated and real values was achieved. The deviation of these values did not exceed 5 %. The designed and verified method does not also consider the influence of other effects, for instance, chemical corrosion or corrosion caused by frost-thaw cycles. However, this method could be a supplementary tool applicable to the study of degradation processes and the estimation of a binder´s durability as well.

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High-Temperature X-ray Powder Diffraction Studies on Perovskite Oxynitrides SrNbO$_2$N and SrTaO$_2$N

New Physics Sae Mulli ◽

10.3938/npsm.67.7 ◽

2017 ◽

Vol 67 (1) ◽

pp. 7-11

Author(s):

Youngguk SON ◽

Ilkyoung JEONG*

Keyword(s):

High Temperature ◽

Powder Diffraction ◽

X Ray

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X-ray powder diffraction data for the superconducting phase Tl0.5Pb0.5Sr2CaCu2O6.5+δ

Powder Diffraction ◽

10.1017/s0885715600019461 ◽

1993 ◽

Vol 8 (4) ◽

pp. 249-250 ◽

Cited By ~ 1

Author(s):

Chan Park ◽

Robert L. Snyder

Keyword(s):

High Temperature ◽

Molten Salt ◽

Diffraction Pattern ◽

Powder Diffraction ◽

Diffraction Data ◽

Superconducting Phase ◽

Powder Diffraction Data ◽

X Ray ◽

High Temperature Superconducting

The X-ray powder diffraction pattern for a sample of the high-temperature superconducting phase Tl0.5Pb0.5Sr2CaCu2O6.5+δ has been determined. The sample was prepared by a molten salt technique and had a Tc of 96 K.

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