scholarly journals Increase the Performances of Lime Finishing Mixes Due to Modification with Calcium Silicate Hydrates

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 399
Author(s):  
Valentina Loganina ◽  
Kristina Sergeeva ◽  
Roman Fediuk ◽  
Valery Uvarov ◽  
Nikolai Vatin ◽  
...  
Keyword(s):  
Solid Solution ◽  
Calcium Silicate ◽  
Building Materials ◽  
Liquid Sodium ◽  
X Ray Diffraction ◽  
Calcium Silicate Hydrates ◽  
Plastic Strength ◽  
Group A ◽  
Sodium Glass ◽  
Xrd Patterns

Lime plaster mixes are becoming more and more popular in the world’s building materials market every year. Therefore, the issue of increasing the efficiency of lime finishing coatings is relevant. The paper aim is the modification of lime binders with specially synthesized calcium silicate hydrates (CSHs). To obtain the CSH filler, liquid sodium glass was used with a silicate module of 1.53–2.9 and a density of 1130–1663 kg/m3. Using differential thermal analysis (DTA), X-ray diffraction (XRD) patterns, synthesized calcium silicate hydrates, as well as dry plaster mixes, and finishing coatings based on using them were studied. The regularities of the filler synthesis were established depending on the temperature, density, and silicate modulus of liquid glass, the amount of the precipitant additive, the rate of its introduction, and the drying mode. As a result of processing the obtained experimental data, a mathematical model was obtained for the composition “lime + CSH”. The phase composition of the filler was revealed, which is characterized by the presence of calcium silicate hydrates of the tobermorite group, a solid solution CSH (B) in the form of a weakly crystallized gel, a solid solution of C–S–H (II), hydrohalites, and calcites. It was found that the use of the fillers into the lime compositions, obtained with the rapid introduction of CaCl2 additive into water glass during the synthesis of the filler, promotes the acceleration of the plastic strength gain of lime compositions. It was revealed that the lime composites with the CSH filler are characterized by reduced shrinkage deformations up to 45%. The introduction of the CSH filler into the lime compositions increases the water resistance of the lime finishing layer by 36%. A technological scheme for the production of the lime dry plaster mixes has been developed; it can be introduced at existing factories of building materials without significant re-equipment of production.

scholarly journals Structure of nanocrystalline calcium silicate hydrates: insights from X-ray diffraction, synchrotron X-ray absorption and nuclear magnetic resonance

2016 ◽  
Vol 49 (3) ◽  
pp. 771-783 ◽  
Author(s):  
Sylvain Grangeon ◽  
Francis Claret ◽  
Cédric Roosz ◽  
Tsutomu Sato ◽  
Stéphane Gaboreau ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Calcium Silicate ◽  
Electron Probe ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Calcium Silicate Hydrates ◽  
Angle Spinning ◽  
X Ray Absorption

The structure of nanocrystalline calcium silicate hydrates (C–S–H) having Ca/Si ratios ranging between 0.57 ± 0.05 and 1.47 ± 0.04 was studied using an electron probe micro-analyser, powder X-ray diffraction,29Si magic angle spinning NMR, and Fourier-transform infrared and synchrotron X-ray absorption spectroscopies. All samples can be described as nanocrystalline and defective tobermorite. At low Ca/Si ratio, the Si chains are defect free and the SiQ3andQ2environments account, respectively, for up to 40.2 ± 1.5% and 55.6 ± 3.0% of the total Si, with part of theQ3Si being attributable to remnants of the synthesis reactant. As the Ca/Si ratio increases up to 0.87 ± 0.02, the SiQ3environment decreases down to 0 and is preferentially replaced by theQ2environment, which reaches 87.9 ± 2.0%. At higher ratios,Q2decreases down to 32.0 ± 7.6% for Ca/Si = 1.38 ± 0.03 and is replaced by theQ1environment, which peaks at 68.1 ± 3.8%. The combination of X-ray diffraction and NMR allowed capturing the depolymerization of Si chains as well as a two-step variation in the layer-to-layer distance. This latter first increases from ∼11.3 Å (for samples having a Ca/Si ratio <∼0.6) up to 12.25 Å at Ca/Si = 0.87 ± 0.02, probably as a result of a weaker layer-to-layer connectivity, and then decreases down to 11 Å when the Ca/Si ratio reaches 1.38 ± 0.03. The decrease in layer-to-layer distance results from the incorporation of interlayer Ca that may form a Ca(OH)2-like structure, nanocrystalline and intermixed with C–S–H layers, at high Ca/Si ratios.

Modified xonotlite–type calcium silicate hydrate slabs for fire doors

2018 ◽  
Vol 36 (2) ◽  
pp. 83-96 ◽  
Author(s):  
Rimantas Levinskas ◽  
Irena Lukošiūtė ◽  
Arūnas Baltušnikas ◽  
Algirdas Kuoga ◽  
Aldona Luobikienė ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Solar Furnace ◽  
Liquid Sodium ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Surface Areas ◽  
Back Door

Xonotlite-type calcium silicate hydrate slabs were examined under the thermal shock conditions in a solar furnace at the Plataforma Solar de Almeria which can reach a peak of 300 W/cm2. We have studied the original slabs as well as those modified with a mixture of liquid sodium silicate including montmorillonite as thermal insulation materials for fire doors applications. The slabs were kept at 950°C for 1 h. We performed X-ray diffraction, thermogravimetry and differential scanning calorimetry analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermal conductivity measurements and determined N2 adsorption/desorption isotherms. X-ray diffraction shows that during the thermal shock at 950°C xonotlite is converted to wollastonite. Specific surface areas of xonotlite slabs decrease due to release of crystalline water molecules. It is possible to maintain temperatures of the back door not exceeding 70°C while the front door is subjected to 950°C for 1-h time periods. The standard requires no more than 140°C at the back door.

scholarly journals Effect of Li Substitution on the Structure and Dielectric Constant of Bi0.5(Na⁠1-xLix)0.5TiO⁠3 (0 ≤ x ≤ 0.20) Solid Solution Series

2020 ◽  
Author(s):  
K Anjali ◽  
T G Ajithkumar ◽  
Pattayil Joy
Keyword(s):  
Solid Solution ◽  
Dielectric Constant ◽  
Sodium Titanate ◽  
Close Correlation ◽  
Solid Solution Series ◽  
X Ray Diffraction ◽  
Spectral Parameters ◽  
Solution Series ◽  
Xrd Patterns ◽  
Li Content

Abstract Bismuth sodium titanate Bi0.5Na0.5TiO3 (BNT) is a lead-free piezoelectric ceramic material with high Curie temperature. The effect of substitution of the smaller ion Li+ for the larger ion Na+ in Bi0.5(Na⁠1−xLix)0.5TiO⁠3 (0 ≤ x ≤ 0.20) on the structure of BNT is studied using powder X-ray diffraction (XRD) and Raman spectroscopy. Rietveld refinement analysis of the powder XRD patterns showed that all the compositions formed under monoclinic Cc space group, with the lattice parameters showing minor changes above x > 0.08. Raman spectral parameters such as position and intensity of a peak also showed a similar trend in the same Li concentration range with increasing Li content. A corresponding change in the variation of the dielectric constant with increasing Li content is observed suggesting a close correlation between the local structure and properties of the different compositions in the Bi0.5(Na⁠1−xLix)0.5TiO⁠3 solid solution series.

Experimental Researches on Microstructure of Nanometer Silicon and Cement-Stabilized Soils

2011 ◽  
Vol 94-96 ◽  
pp. 358-364 ◽  
Author(s):  
Li Feng Wang
Keyword(s):  
Compressive Strength ◽  
Calcium Silicate ◽  
Unconfined Compressive Strength ◽  
Silicon Powder ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
Calcium Silicate Hydrates ◽  
Stabilized Soil ◽  
Experimental Researches

Unconfined compressive strength of various mixing proportions and ages of nanometer silicon and cement-stabilized soils（NCSS） are tested ,and the rules of compressive strength are got. Hydration products and microstructures of NCSS are discussed by means of XRD and SEM technology, and microstructural mechanisms of NCSS are analyzed. Results show that nanometer silicon powder added to cement-stabilized soil(CSS) can sharply improve the compressive strength of CSS. More Calcium silicate hydrates(C-S-H) and other hydration products can be produced in the process of secondary reaction of cement and water added nanometer silicon powder. X ray diffraction tests indicate the kinds and quantities of C-S-H increase with nanometer silicon contents. Strengths of NCSS are bettered by increasing jointed strength changed from edge-edge, edge-face connectios to cementation connections affected by increasing hydration products. Large pores of NCSS can be greatly decreased by adding nanometer silicon powder, and hydration products filling in the pores make NCSS more dense materials.

How Fe60Co40 and Fe72Al28 Nano-Alloys Produced by Mechanical Alloying Behave when Exposed to Microwaves

2008 ◽  
Vol 584-586 ◽  
pp. 977-981 ◽  
Author(s):  
Fadhela Otmane ◽  
S. Bergheul ◽  
Z. Hamlati ◽  
M. Azzaz
Keyword(s):  
Solid Solution ◽  
Mechanical Alloying ◽  
Reflection Loss ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphological Studies ◽  
X Band ◽  
Average Grain Size ◽  
Xrd Patterns

Fe60Co40 and Fe72Al28 nano-alloys were synthesized from elemental powders via highenergy mechanical alloying. The prepared samples were characterized using X-ray diffraction, scanning electron microscopy and X-band waveguide to measure the reflection loss in a frequency range of 9-10 GHz. The XRD patterns show that disordered Fe60Co40 solid solution with a bodycentred cubic structure is formed for milling times longer than 12 h, and after 4h milling, the solid solution Fe72Al28 has been largely formed. Morphological studies indicate an average grain size of 10 to 15 nm. The microwave- absorbing characteristic reveal good performance for Fe60Co40 compared to Fe72Al28, the maximum reflection loss is about -12 dB for the absorber.

Mechanical Performance of the Phosphogypsum Baking-free Bricks

2021 ◽  
Vol 14 ◽  
Author(s):  
Xiaoyu Guo ◽  
Yajing Mao ◽  
Lizhai Pei ◽  
Chuangang Fan
Keyword(s):  
Compressive Strength ◽  
Building Materials ◽  
Mechanical Performance ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
Consolidation Process ◽  
X Ray ◽  
Freeze Thaw ◽  
Xrd Patterns ◽  
Softening Coefficient

Background: A large amount of phosphogypsum occupies the land and causes the environmental pollution. It is of great research significance and urgency to utilization of the phosphogypsum. Methods: The influence of the ratio of the cementing materials and phosphogypsum (C/P ratio) on the compressive strength, water absorption, softening coefficient and freeze-thaw stability of the phosphogypsum baking-free bricks was investigated. The consolidation process of the phosphogypsum baking-free bricks was analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results: XRD patterns show that the phosphogypsum baking-free bricks curved for 28 d are mainly composed of monoclinic CaSO4•2H2O and hexagonal Ca6Al2(SO4)3(OH)12•26H2O (Aft) phases. SEM observation shows that the phosphogypsum bricks consist of Aft nanorods and irregular microscale particles. The softening coefficient, water-resistant performance and freeze-thaw stability of the phosphogypsum baking-free bricks remarkably decrease with decreasing the C/P ratio. 28 d compressive strength decreases from 26.42 MPa to 15.58 MPa with the change of the C/P ratio from 1:1 to 1:2.5. The optimal ratio of the cementing materials and phosphogymsum is 1:1. The phosphogypsum baking-free bricks exhibit good stability after 18 freeze-thaw cycles. Conclusion: Phosphogypsum baking-free bricks were prepared by natural curing process using phosphogypsum as the raw materials, cement, slag, fly ash and silica fume as the cementing materials. The phosphogypsum baking-free bricks exhibit great application in the field of the building materials.

Structural and Magnetic Hysteresis Properties of Co-Zr Substituted Hexagonal Barium Ferrites

2015 ◽  
Vol 7 (1) ◽  
pp. 1346-1351
Author(s):  
Ch.Gopal Reddy ◽  
Ch. Venkateshwarlu ◽  
P. Vijaya Bhasker Reddy
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Magnetic Hysteresis ◽  
Grain Morphology ◽  
Hexagonal Structure ◽  
Ion Composition ◽  
X Ray Diffraction ◽  
Ceramic Method ◽  
Barium Ferrites ◽  
Xrd Patterns

Co-Zr substituted M-type hexagonal barium ferrites, with chemical formula BaCoxZrxFe12-2xO19 (where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), have been synthesized by double sintering ceramic method. The crystallographic properties, grain morphology and magnetic properties of these ferrites have been investigated by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM). The XRD patterns confirm the single phase with hexagonal structure of prepared ferrites. The magnetic properties have been investigated as a function of Co and Zr ion composition at an applied field in the range of 20 KOe. These studies indicate that the saturation magnetization (Ms) in the samples increases initially up to the Co-Zr composition of x=0.6 and decreases thereafter. On the other hand, the coercivity (Hc) and Remanent magnetization (Mr) are found to decrease continuously with increasing Co-Zr content. This property is most useful in permanent magnetic recording. The observed results are explained on the basis of site occupation of Co and Zr ions in the samples.

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