scholarly journals Permeable Nanomontmorillonite and Fibre Reinforced Cementitious Binders

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3245 ◽  
Author(s):  
Styliani Papatzani ◽  
Sotirios Grammatikos ◽  
Kevin Paine
Keyword(s):  
Mercury Intrusion Porosimetry ◽  
Pozzolanic Reaction ◽  
Particle Packing ◽  
X Ray Diffraction ◽  
Viable Option ◽  
Backscattered Electron Imaging ◽  
X Ray ◽  
Different Types ◽  
Backscattered Electron ◽  
Electron Imaging

Clinker reduction in cementitious binders is of paramount importance today, and nanotechnology has extended permissible limits. In the present study, a reference binder consisting of 60% Portland cement, 20% limestone, 20% fly ash, 3% polyvinyl alcohol (PVA) fibres and 2% superplasticizer is optimized with three different types of nano-montmorillonite (nMt) dispersions; two organomodified ones and an inorganic one at different proportions (0.5% to 4%). Flexural strength, measured on day 7, 28, 56 and 90, was improved after day 28 with the addition of inorganic nMt. Thermal gravimetric analyses carried out on day 7, 28, 56 and 90 coupled with x-ray diffraction (at day 28) showed a distinctively enhanced pozzolanic reaction. Backscattered electron imaging confirmed changes in the microstructure. Late age relative density measurements of the nMt cementitious nanocomposites showed higher values than these of the reference paste, which can be attributed to better particle packing. Mercury intrusion porosimetry measurements give support to the optimal nMt dosage, being 1% by total mass of binder and water impermeability tests (modified with BS EN 492:2012) suggest that inorganic nMt can be a viable option material where permeability constitutes a prerequisite. Suggestions for further activation of the nMt-fibre reinforced cementitious nanocomposites were also made.

Differential REE uptake by sector growth of monazite

1999 ◽  
Vol 63 (6) ◽  
pp. 813-828 ◽  
Author(s):  
G. Cressey ◽  
F. Wall ◽  
B. A. Cressey
Keyword(s):  
Single Crystal ◽  
Microprobe Analysis ◽  
X Ray Diffraction ◽  
Backscattered Electron Imaging ◽  
X Ray ◽  
Backscattered Electron ◽  
Kink Site ◽  
Electron Imaging ◽  
The Relationship

AbstractMonazite-(Ce) from a dolomite carbonatite at Kangankunde, Malawi, is sector-zoned with variation in La2O3 of up to 6.0 wt.% and in Nd2O3 of up to 3.9 wt.% between sectors. Single crystal X-ray diffraction, backscattered electron imaging and microprobe analysis have been used to establish the relationship between the morphology and sector chemistry of this low-Th monazite, (Ce,La,Nd)PO4. Uptake of La by {011} sector surfaces is enhanced relative to that of and {100} sectors; Ce shows no partitioning differences; and uptake of Nd is more easily facilitated on and {100} surfaces relative to {011}. There appears to be a distinct relationship between the size of the REE ion and the probability of uptake via the different growth surfaces. Interpretation of this uptake behaviour, based on theories involving ‘protosites’, involves an investigation of the possible kink site geometries at edge-steps during growth. Part-formed kink sites with small entrance sizes are calculated to occur with higher frequency on relative to {011}, and this correlates with an increase in the smaller-sized REE (Nd) uptake by growth surfaces. The overall morphology and sector growth is suggested to be a function of uptake chemistry.

scholarly journals Phase relationships in the Al-rich region of the Al-Y-Zr system

2017 ◽  
Vol 53 (1) ◽  
pp. 9-12 ◽  
Author(s):  
X. Bao ◽  
L. Liu ◽  
S. Huang ◽  
Y. Jiang ◽  
X. Wang ◽  
...  
Keyword(s):  
First Principle ◽  
Rich Region ◽  
Backscattered Electron Imaging ◽  
X Ray ◽  
First Principle Calculations ◽  
Three Phase ◽  
Backscattered Electron ◽  
Electron Imaging ◽  
Scanning Electron ◽  
Phase Relationships

The phase relations in the Al-Y-Zr ternary system at 873 K have been investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) in backscattered electron imaging (BSE) modes. Six three-phase equilibria are determined and no ternary compound is observed. In the meantime, first principle calculations are used to provide theoretical guidance to understand the experimental results.

scholarly journals Silicon location through backscattered electron imaging and X-ray microanalysis in leaves of Cyperus ligularis L. and Rhynchospora aberrans C. B. Clarke (Cyperaceae)

2012 ◽  
Vol 26 (2) ◽  
pp. 275-280 ◽  
Author(s):  
Maria Emília Maranhão Estelita ◽  
Ana Claudia Rodrigues
Keyword(s):  
Cell Walls ◽  
Colloidal Silica ◽  
Structural Changes ◽  
Epidermal Cells ◽  
Vascular Bundles ◽  
Backscattered Electron Imaging ◽  
X Ray ◽  
Backscattered Electron ◽  
Taxonomic Groups ◽  
Electron Imaging

The Cyperaceae show the ability to incorporate silicon by depositing colloidal silica, which is recorded by the occurrence of projections in the form of cones, in inner tangential walls of some epidermal cells or "silica cells". Leaves of C. ligularis and R. aberrans were analyzed through the technique of electron backscatter. Cyperus ligularis accumulates silica, in addition to "silica cells", in some stomata, trichomes and the cell walls that surround the cavities of the aerenchyma. The silica in the latter occurs in various forms; however, the cells located near the vascular bundles have conical projections, similar to those of the epidermis. Rhynchospora aberrans presents "silica cells" whose projections have tapered "satellites". In this species, silica also occurs in stomata and certain epidermal cells adjacent to them. It appears that the silicon deposition occurs in combination with the wall (with no apparent structural changes), and structures of secretion, or projections of the wall. These structural changes in the species, and location, are probably related to functional and environmental factors, especially the soil, in addition to relation with taxonomic groups.

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