scholarly journals Inventive Microstructural and Durability Investigation of Cementitious Composites Involving Crystalline Waterproofing Admixtures and Portland Limestone Cement

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1425 ◽  
Author(s):  
Pejman Azarsa ◽  
Rishi Gupta ◽  
Alireza Biparva
Keyword(s):  
Chemical Elements ◽  
Cementitious Composites ◽  
Chemical Compositions ◽  
Crystal Formation ◽  
Polished Section ◽  
Limited Information ◽  
Sem Images ◽  
X Ray ◽  
Portland Limestone Cement ◽  
Limestone Cement

The durability of a cement-based material is mainly dependent on its permeability. Modifications of porosity, pore-structure and pore-connectivity could have significant impacts on permeability improvement, which eventually leads to more durable materials. One of the most efficient solutions in this regard is to use permeability reducing admixtures (PRA). Among these admixtures for those structures exposed to hydro-static pressure, crystalline waterproofing admixtures (CWA) have been serving in the construction industries for decades and according to ACI 212—chemical admixtures’ report, it has proven its capability in permeability reduction and durability-enhancement. However, there is substantial research being done on its durability properties at the macro level but very limited information available regarding its microstructural features and chemical characteristics at the micro level. Hence, this paper presents one of the first reported attempts to characterize microstructural and chemical elements of hydration products for cementitious composites with CWA called K, P and X using Scanning Electron Microscopy (SEM). Backscattered SEM images taken from a polished-section of one CWA type—K—admixture were analyzed in ImageJ to obtain paste matrix porosity, indicating a lower value for the CWA-K mixture. X-ray analysis and SEM micrographs of polished sections were examined to identify chemical compositions based on atomic ratio plots and brightness differences in backscatter-SEM images. To detect chemical elements and the nature of formed crystals, the fractured surfaces of three different CWA mixtures were examined. Cementitious composites with K admixture indicated needle-like crystal formation—though different from ettringite; X and P admixtures showed sulfur peaks in Energy Dispersive Spectrum (EDS) spectra, like ettringite. SEM images and X-ray analyses of mixtures incorporating Portland Limestone Cement (PLC) indicated lower-than-average porosity but showed different Si/Ca and Al/Ca atomic ratios.

scholarly journals Analysis of Chemical Composition of Portland Cement in Ghana: A Key to Understand the Behavior of Cement

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Mark Bediako ◽  
Eric Opoku Amankwah
Keyword(s):  
Chemical Composition ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Chemical Compositions ◽  
Test Results ◽  
Brand Name ◽  
X Ray ◽  
Portland Limestone Cement ◽  
Limestone Cement ◽  
Construction Works

The performance of Portland cement in concrete or mortar formation is very well influenced by chemical compositions among other factors. Many engineers usually have little information on the chemical compositions of cement in making decisions for the choice of commercially available Portland cement in Ghana. This work analyzed five different brands of Portland cement in Ghana, namely, Ghacem ordinary Portland cement (OPC) and Portland limestone cement (PLC), CSIR-BRRI Pozzomix, Dangote OPC, and Diamond PLC. The chemical compositions were analyzed with X-Ray Fluorescence (XRF) spectrometer. Student’st-test was used to test the significance of the variation in chemical composition between standard literature values and each of the commercial cement brands. Analysis of variance (ANOVA) was also used to establish the extent of variations between chemical compositions and brand name of the all commercial Portland cement brands. Student’st-test results showed that there were no significant differences between standard chemical composition values and that of commercial Portland cement. The ANOVA results also indicated that each brand of commercial Portland cement varies in terms of chemical composition; however, the specific brands of cement had no significant differences. The study recommended that using any brand of cement in Ghana was good for any construction works be it concrete or mortar formation.

scholarly journals Industrial Waste Utilization of Carbon Dust in Sustainable Cementitious Composites Production

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3295
Author(s):  
Mohammad R. Irshidat ◽  
Nasser Al-Nuaimi
Keyword(s):  
Compressive Strength ◽  
Industrial Waste ◽  
Cement Mortar ◽  
Waste Utilization ◽  
Cementitious Composites ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Compact Structure ◽  
X Ray ◽  
Industrial Waste Utilization

This paper experimentally investigates the effect of utilization of carbon dust generated as an industrial waste from aluminum factories in cementitious composites production. Carbon dust is collected, characterized, and then used to partially replace cement particles in cement mortar production. The effect of adding different dosages of carbon dust in the range of 5% to 40% by weight of cement on compressive strength, microstructure, and chemical composition of cement mortar is investigated. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray fluorescence (XRF) analysis are used to justify the results. Experimental results show that incorporation of carbon dust in cement mortar production not only reduces its environmental side effects but also enhances the strength of cementitious composites. Up to 10% carbon dust by weight of cement can be added to the mixture without adversely affecting the strength of the mortar. Any further addition of carbon dust would decrease the strength. Best enhancement in compressive strength (27%) is achieved in the case of using 5% replacement ratio. SEM images show that incorporation of small amount of carbon dust (less than 10%) lead to produce denser and more compact-structure cement mortar.

Alumina Residue Characterization to Produce Tubular Ceramic Membranes

2012 ◽  
Vol 727-728 ◽  
pp. 1508-1513 ◽  
Author(s):  
Iliana Oliveira Guimarães ◽  
Hélio Lucena Lira ◽  
Sidinei Kleber da Silva ◽  
Suellen Lisboa Dias ◽  
Rosa do Carmo de Oliveira Lima
Keyword(s):  
Electrostatic Precipitator ◽  
Raw Materials ◽  
Environmental Issues ◽  
Ceramic Membranes ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Calcination Process ◽  
X Ray ◽  
Two Samples

ndustrial wastes recycling become attractive due to raw materials economy (sustainability) and environmental issues. This research objective was to characterize a residue generated during the alumina calcination process (electrostatic precipitator dust), to be applied on the development of tubular ceramic membranes. In this context, two samples were analyzed, a crude residue (sample A) as supplied by the industry and other calcined residue (sample B). As verified by X-ray fluorescence spectroscopy by dispersive energy (XDE), the samples A and B showed a high content of alumina in chemical compositions, both close to 96%. Gibbsite and α-alumina crystalline phases were identified by X-ray diffraction (XRD) in the samples. At scanning electron microscopy (SEM) images, could be observed agglomerates of particles with asymmetric shapes and a wide particle size distribution like was confirmed by laser diffraction, which showed that the particles diameters remained almost unchanged after calcination at 700°C. Results revealed no significant differences between samples characteristics, indicating that the crude and calcined residues could be used to prepare ceramic membranes.

Sveite from the Northeastern San Joaquin Valley, California

2021 ◽  
Author(s):  
Ronald C. Peterson ◽  
Robert C. Graham ◽  
Jarel O. Ervin ◽  
Igor S. Kozin ◽  
James O. Sickman ◽  
...  
Keyword(s):  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Mineral Occurrence ◽  
Diffraction Patterns ◽  
Biogenic Source ◽  
Water Extractable ◽  
Structure Water ◽  
Bird Feces

ABSTRACT Sveite [KAl7(NO3)4(OH)16Cl2·8H2O] first described from Venezuela and material recently collected from northern California have similar X-ray diffraction patterns and chemical compositions. The main difference in the chemical composition is the absence of significant chlorine and sulfate in the sveite from California. The changes observed by X-ray diffraction upon hydration and the SEM images of the crystals suggest a layered atomic structure. Water-extractable NO3 in the Venezuelan sveite sample is isotopically enriched in δ15N and δ18O and likely was affected by the microbial process of denitrification. In contrast, the extractable nitrate from the California sveite is less isotopically enriched than the Venezuelan mineral and there is only modest evidence that denitrification had affected its isotopic composition. Overall, the nitrate in the California sveite is isotopically similar to nitrate present in acidic soils overlying the mineral occurrence, suggesting a general biogenic source of uric acid from bird feces for the mineral-bound nitrogen.

Techniques for cryoultramicrotomy of propane jet frozen biological samples

1986 ◽  
Vol 44 ◽  
pp. 260-261
Author(s):  
B. Craig ◽  
L. Hawkey ◽  
A. LeFurgey
Keyword(s):  
Freeze Fracture ◽  
Freeze Substitution ◽  
Heart Cells ◽  
Crystal Formation ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Chick Heart ◽  
Embryonic Chick Heart ◽  
A New Technique

Ultra-rapid freezing followed by cryoultramicrotomy is essential for the preservation of diffusible elements in situ within cells prior to scanning transmission electron microscopy and quantitative energy dispersive x-ray microanalysis. For cells or tissue fragments in suspension and for monolayer cell cultures, propane jet freezing provides cooling rates greater than 30,000°C/sec with regions up to 40μm in thickness free of significant ice crystal formation. While this method of freezing has frequently been applied prior to freeze fracture or freeze substitution, it has not been widely utilized prior to cryoultramicrotomy and subsequent x-ray microanalytical studies. This report describes methods devised in our laboratory for cryosectioning of propane jet frozen kidney proximal tubule suspensions and cultured embryonic chick heart cells, in particular a new technique for mounting frozen suspension specimens for sectioning. The techniques utilize the same specimen supports and sample holders as those used for freeze fracture and freeze substitution and should be generally applicable to any cell suspension or culture preparation.

Mosaic Mapping: A Means of Tiling Images to Shorten Acquisition Speed for Lower - Magnification SEM Images and Wavelength Dispersive Spectrometers (WDS) X-Ray Maps

1996 ◽  
Vol 54 ◽  
pp. 438-439
Author(s):  
J.D. Geller ◽  
C.R. Herrington
Keyword(s):  
Limiting Factors ◽  
X Rays ◽  
Angular Range ◽  
Acceptance Angle ◽  
Sem Images ◽  
Worst Case ◽  
X Ray ◽  
Focusing Distance ◽  
Layered Crystals ◽  
Working Distance

The minimum magnification for which an image can be acquired is determined by the design and implementation of the electron optical column and the scanning and display electronics. It is also a function of the working distance and, possibly, the accelerating voltage. For secondary and backscattered electron images there are usually no other limiting factors. However, for x-ray maps there are further considerations. The energy-dispersive x-ray spectrometers (EDS) have a much larger solid angle of detection that for WDS. They also do not suffer from Bragg’s Law focusing effects which limit the angular range and focusing distance from the diffracting crystal. In practical terms EDS maps can be acquired at the lowest magnification of the SEM, assuming the collimator does not cutoff the x-ray signal. For WDS the focusing properties of the crystal limits the angular range of acceptance of the incident x-radiation. The range is dependent upon the 2d spacing of the crystal, with the acceptance angle increasing with 2d spacing. The natural line width of the x-ray also plays a role. For the metal layered crystals used to diffract soft x-rays, such as Be - O, the minimum magnification is approximately 100X. In the worst case, for the LEF crystal which diffracts Ti - Zn, ˜1000X is the minimum.

X-ray mapping without STEM

1994 ◽  
Vol 52 ◽  
pp. 508-509
Author(s):  
Judith M. Brock ◽  
Max T. Otten
Keyword(s):  
Life Science ◽  
Materials Science ◽  
Chemical Elements ◽  
Full Description ◽  
Scanning System ◽  
Elemental Distribution ◽  
X Ray ◽  
Transmission Electron ◽  
Distribution Of Elements ◽  
Made In

A knowledge of the distribution of chemical elements in a specimen is often highly useful. In materials science specimens features such as grain boundaries and precipitates generally force a certain order on mental distribution, so that a single profile away from the boundary or precipitate gives a full description of all relevant data. No such simplicity can be assumed in life science specimens, where elements can occur various combinations and in different concentrations in tissue. In the latter case a two-dimensional elemental-distribution image is required to describe the material adequately. X-ray mapping provides such of the distribution of elements.The big disadvantage of x-ray mapping hitherto has been one requirement: the transmission electron microscope must have the scanning function. In cases where the STEM functionality – to record scanning images using a variety of STEM detectors – is not used, but only x-ray mapping is intended, a significant investment must still be made in the scanning system: electronics that drive the beam, detectors for generating the scanning images, and monitors for displaying and recording the images.

Processing of granite quarry solid waste into industrial high silica materials using leaching process with HCl concentration variation

2020 ◽  
Vol 11 (2) ◽  
pp. 43-50
Author(s):  
Yusup Hendronursito ◽  
Muhammad Amin ◽  
Slamet Sumardi ◽  
Roniyus Marjunus ◽  
Frista Clarasati ◽  
...  
Keyword(s):  
Particle Size ◽  
Rotational Speed ◽  
Inductively Coupled Plasma ◽  
Chemical Elements ◽  
Silica Content ◽  
X Ray ◽  
Concentration Variation ◽  
Leaching Process ◽  
Hcl Concentration ◽  
Granite Powder

This study was aimed to increase granite's silica content using the leaching process with HCl concentration variation. The granite used in this study came from Lematang, South Lampung. This study aims to determine the effect of variations in HCl concentration, particle size, and rotational speed on the crystalline phase and chemical elements formed in the silica product produced from granite. The HCl concentration variations were 6.0 M, 7.2 M, 8.4 M, and 9.6 M, the variation in particle size used was 270 and 400 mesh. Variations in rotational speed during leaching were 500 and 750 rpm. Granite powder was calcined at 1000 ºC for 2 hours. Characterization was performed using X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP- OES). The results showed that the silica content increased with increasing HCl concentration, the finer the particle size, and the higher the rotational speed. XRF analysis showed that the silica with the highest purity was leached with 9.6 HCl with a particle size of 400 mesh and a rotational speed of of 750 rpm, which was 73.49%. Based on the results above, by leaching using HCl, the Si content can increase from before. The XRD diffractogram showed that the granite powder formed the Quartz phase.

scholarly journals Hydrochloric Acid Modification and Lead Removal Studies on Naturally Occurring Zeolites from Nevada, New Mexico, and Arizona

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1238
Author(s):  
Garven M. Huntley ◽  
Rudy L. Luck ◽  
Michael E. Mullins ◽  
Nick K. Newberry
Keyword(s):  
New Mexico ◽  
Surface Area ◽  
Bet Surface Area ◽  
Lead Removal ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Naturally Occurring ◽  
27Al Mas Nmr ◽  
Modified Zeolites

Four naturally occurring zeolites were examined to verify their assignments as chabazites AZLB-Ca and AZLB-Na (Bowie, Arizona) and clinoptilolites NM-Ca (Winston, New Mexico) and NV-Na (Ash Meadows, Nevada). Based on powder X-ray diffraction, NM-Ca was discovered to be mostly quartz with some clinoptilolite residues. Treatment with concentrated HCl (12.1 M) acid resulted in AZLB-Ca and AZLB-Na, the chabazite-like species, becoming amorphous, as confirmed by powder X-ray diffraction. In contrast, NM-Ca and NV-Na, which are clinoptilolite-like species, withstood boiling in concentrated HCl acid. This treatment removes calcium, magnesium, sodium, potassium, aluminum, and iron atoms or ions from the framework while leaving the silicon framework intact as confirmed via X-ray fluorescence and diffraction. SEM images on calcined and HCl treated NV-Na were obtained. BET surface area analysis confirmed an increase in surface area for the two zeolites after treatment, NM-Ca 20.0(1) to 111(4) m2/g and NV-Na 19.0(4) to 158(7) m2/g. 29Si and 27Al MAS NMR were performed on the natural and treated NV-Na zeolite, and the data for the natural NV-Na zeolite suggested a Si:Al ratio of 4.33 similar to that determined by X-Ray fluorescence of 4.55. Removal of lead ions from solution decreased from the native NM-Ca, 0.27(14), NV-Na, 1.50(17) meq/g compared to the modified zeolites, 30 min HCl treated NM-Ca 0.06(9) and NV-Na, 0.41(23) meq/g, and also decreased upon K+ ion pretreatment in the HCl modified zeolites.

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