Corrosion of rebar in concrete is commonly associated with, and to a large degree influenced by, ... more Corrosion of rebar in concrete is commonly associated with, and to a large degree influenced by, the free chloride concentration in the pore water. It is standard industry practice to add various mineral admixtures such as pulverised fuel ash (PFA), or fly ash, ground granulated blast furnace slag (GGBS) and silica fume (SF), to concrete mixtures to increase the corrosion resistance of the reinforcement in the matrix and its subsequent design life span. Various investigations have reported on the effect of mineral admixtures and additions on chloride binding in cementitious matrices, and the current study contributes further to knowledge in this field. Unlike previous investigations, this study attempted to make a clear distinction between the contributions of the two components in a blended cement consisting of ordinary Portland cement (OPC) and ground blast furnace slag (BFS). These contributions of each component have been quantified. Relationships between the total amount of chl...
Heavy mineral sands are the source of various commodities such as white titanium dioxide pigment ... more Heavy mineral sands are the source of various commodities such as white titanium dioxide pigment and titanium metal. The three case studies in this paper show the value of X-ray diffraction (XRD) and statistical methods such as data clustering for process optimization and quality control during heavy mineral processing. The potential of XRD as an automatable, reliable tool, useful in the characterization of heavy mineral concentrates, product streams and titania slag is demonstrated. The recent development of ultra-high-speed X-ray detectors and automated quantification allows for ‘on the fly’ quantitative X-ray diffraction analysis and truly interactive process control, especially in the sector of heavy mineral concentration and processing. Apart from the information about the composition of a raw ore, heavy mineral concentrate and the various product streams or titania slag, this paper provides useful information by the quantitative determination of the crystalline phases and the ...
In this paper the use of slags, from ferro- and silicomanganese alloy production as well as from ... more In this paper the use of slags, from ferro- and silicomanganese alloy production as well as from the production of Pt-group element concentrates in blended cements, is discussed. The properties of the mixtures depend on the cement type, the mixtures, and the different manufacturers. Some cement performs better than others. The results are promising, but show variable behavior depending on slag and cement composition. Compressive strength tests as well as heat flow curves showing the hydration behaviour, indicate that 10-20% addition of these slags to ordinary Portland cement is possible. These slags can be used as additions to cements to produce composite cements fulfilling the requirements up to 42.5N MPa class. By the addition of slag, the amount of calcium carbonate necessary for clinker production is reduced and, therefore, CO₂ emissions are decreased. Also, large slag stock piles can be avoided.
Ba(3−x)Srx(PO4)2 orthophosphates (0≤x≤3) have been prepared by solid state reaction. The final te... more Ba(3−x)Srx(PO4)2 orthophosphates (0≤x≤3) have been prepared by solid state reaction. The final temperature was 1000°C. The X-ray diffraction analyses show the existence of a continuous solid solution. Ba(3−x)Srx(PO4)2 orthophosphates (0≤x≤3) crystallize in the hexagonal system with the space group R3m. Their structure is based on a three-dimensional framework constructed of infinite layers of Ba1/Sr1O12 linked and parallel to infinite layers of Ba2/Sr2O10 polyhedra and PO4 tetrahedra.
The compound ammonium D-gluconate (C6H11O7−NH4+) has been studied by X-ray powder diffraction. Th... more The compound ammonium D-gluconate (C6H11O7−NH4+) has been studied by X-ray powder diffraction. The powder diffraction pattern and data obtained at room temperature are presented (cell data and powder data summary).
Samples originating from the UG-2 of the Bushveld Igneous Complex, South Africa, contain varying ... more Samples originating from the UG-2 of the Bushveld Igneous Complex, South Africa, contain varying amounts of chromite. Most laboratories, including the Pretoria University’s Facility, use the current Powder Diffraction File (PDF) maintained by the International Centre for Diffraction Data (ICDD), for the qualitative data interpretation. The chromites that show the closest fit to that of UG-2 chromite, do not resemble its chemical composition. In this paper the new powder diffraction data is presented for the UG-2 chromite with an average composition of: (Fe2+0.55Mg0.43Ti0.02)(Cr1.14Fe3+0.23Al0.63)O4.
X-ray analysis of polycrystalline powder samples has grown beyond its roots in the world of labor... more X-ray analysis of polycrystalline powder samples has grown beyond its roots in the world of laboratory research and is regarded as one of the most powerful industrial process-control tools in the field of building materials and minerals. This is the key to characterize the element and the phase composition of the material. This is largely due to the development of industrial X-ray analytical systems, which have transformed these advanced analytical techniques born in the laboratory into a robust, workmanlike and easy-to-use tool for today’s heavy industries. X-ray diffraction (phase analysis) opens enormous possibilities for process and quality control. Moreover, the recent development of ultra-high-speed X-ray detectors allows for “on the fly” quantitative X-ray diffraction analysis and truly interactive process control. Hydration of cements can be studied relative ease. Additionally Computed X-ray Tomography (CT) can yield valuable information in the study of mortars and concrete.
Hydrogen bonding between poly(methyl vinyl ether-co-maleic acid) (PMVE–MA) and poly(vinyl alcohol... more Hydrogen bonding between poly(methyl vinyl ether-co-maleic acid) (PMVE–MA) and poly(vinyl alcohol) (PVOH) has resulted in films with lower oxygen transmission rates (OTR) than pure PVOH. In the range 20–30% (w/w) PMVE–MA, complexation between the two polymers in the blend was maximized, as shown by viscometry, Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) analysis. OTR measurements have shown
A commercial layered double hydroxide (LDH) with nominal composition was intercalated with lauric... more A commercial layered double hydroxide (LDH) with nominal composition was intercalated with lauric and stearic acid using a surfactant-assisted method. X-ray diffraction, thermal analysis and infrared spectroscopy confirmed that bilayer-intercalated compounds were ...
Raman spectra of synthetic “braggite” (Pt, Pd, Ni)S with variable Pt/Pd ratios (atomic ratios bet... more Raman spectra of synthetic “braggite” (Pt, Pd, Ni)S with variable Pt/Pd ratios (atomic ratios between 0.31 and 1.37) and saturated in Ni (up to 1.99 atomic %) have been recorded and compared with the Raman spectra of synthetic “cooperite” and the pure palladium and platinum sulfides. In order to obtain more information on the significant differences in the spectra of these synthetic samples, factor group analyses of “braggite” and “cooperite” have been performed.
Corrosion of rebar in concrete is commonly associated with, and to a large degree influenced by, ... more Corrosion of rebar in concrete is commonly associated with, and to a large degree influenced by, the free chloride concentration in the pore water. It is standard industry practice to add various mineral admixtures such as pulverised fuel ash (PFA), or fly ash, ground granulated blast furnace slag (GGBS) and silica fume (SF), to concrete mixtures to increase the corrosion resistance of the reinforcement in the matrix and its subsequent design life span. Various investigations have reported on the effect of mineral admixtures and additions on chloride binding in cementitious matrices, and the current study contributes further to knowledge in this field. Unlike previous investigations, this study attempted to make a clear distinction between the contributions of the two components in a blended cement consisting of ordinary Portland cement (OPC) and ground blast furnace slag (BFS). These contributions of each component have been quantified. Relationships between the total amount of chl...
Heavy mineral sands are the source of various commodities such as white titanium dioxide pigment ... more Heavy mineral sands are the source of various commodities such as white titanium dioxide pigment and titanium metal. The three case studies in this paper show the value of X-ray diffraction (XRD) and statistical methods such as data clustering for process optimization and quality control during heavy mineral processing. The potential of XRD as an automatable, reliable tool, useful in the characterization of heavy mineral concentrates, product streams and titania slag is demonstrated. The recent development of ultra-high-speed X-ray detectors and automated quantification allows for ‘on the fly’ quantitative X-ray diffraction analysis and truly interactive process control, especially in the sector of heavy mineral concentration and processing. Apart from the information about the composition of a raw ore, heavy mineral concentrate and the various product streams or titania slag, this paper provides useful information by the quantitative determination of the crystalline phases and the ...
In this paper the use of slags, from ferro- and silicomanganese alloy production as well as from ... more In this paper the use of slags, from ferro- and silicomanganese alloy production as well as from the production of Pt-group element concentrates in blended cements, is discussed. The properties of the mixtures depend on the cement type, the mixtures, and the different manufacturers. Some cement performs better than others. The results are promising, but show variable behavior depending on slag and cement composition. Compressive strength tests as well as heat flow curves showing the hydration behaviour, indicate that 10-20% addition of these slags to ordinary Portland cement is possible. These slags can be used as additions to cements to produce composite cements fulfilling the requirements up to 42.5N MPa class. By the addition of slag, the amount of calcium carbonate necessary for clinker production is reduced and, therefore, CO₂ emissions are decreased. Also, large slag stock piles can be avoided.
Ba(3−x)Srx(PO4)2 orthophosphates (0≤x≤3) have been prepared by solid state reaction. The final te... more Ba(3−x)Srx(PO4)2 orthophosphates (0≤x≤3) have been prepared by solid state reaction. The final temperature was 1000°C. The X-ray diffraction analyses show the existence of a continuous solid solution. Ba(3−x)Srx(PO4)2 orthophosphates (0≤x≤3) crystallize in the hexagonal system with the space group R3m. Their structure is based on a three-dimensional framework constructed of infinite layers of Ba1/Sr1O12 linked and parallel to infinite layers of Ba2/Sr2O10 polyhedra and PO4 tetrahedra.
The compound ammonium D-gluconate (C6H11O7−NH4+) has been studied by X-ray powder diffraction. Th... more The compound ammonium D-gluconate (C6H11O7−NH4+) has been studied by X-ray powder diffraction. The powder diffraction pattern and data obtained at room temperature are presented (cell data and powder data summary).
Samples originating from the UG-2 of the Bushveld Igneous Complex, South Africa, contain varying ... more Samples originating from the UG-2 of the Bushveld Igneous Complex, South Africa, contain varying amounts of chromite. Most laboratories, including the Pretoria University’s Facility, use the current Powder Diffraction File (PDF) maintained by the International Centre for Diffraction Data (ICDD), for the qualitative data interpretation. The chromites that show the closest fit to that of UG-2 chromite, do not resemble its chemical composition. In this paper the new powder diffraction data is presented for the UG-2 chromite with an average composition of: (Fe2+0.55Mg0.43Ti0.02)(Cr1.14Fe3+0.23Al0.63)O4.
X-ray analysis of polycrystalline powder samples has grown beyond its roots in the world of labor... more X-ray analysis of polycrystalline powder samples has grown beyond its roots in the world of laboratory research and is regarded as one of the most powerful industrial process-control tools in the field of building materials and minerals. This is the key to characterize the element and the phase composition of the material. This is largely due to the development of industrial X-ray analytical systems, which have transformed these advanced analytical techniques born in the laboratory into a robust, workmanlike and easy-to-use tool for today’s heavy industries. X-ray diffraction (phase analysis) opens enormous possibilities for process and quality control. Moreover, the recent development of ultra-high-speed X-ray detectors allows for “on the fly” quantitative X-ray diffraction analysis and truly interactive process control. Hydration of cements can be studied relative ease. Additionally Computed X-ray Tomography (CT) can yield valuable information in the study of mortars and concrete.
Hydrogen bonding between poly(methyl vinyl ether-co-maleic acid) (PMVE–MA) and poly(vinyl alcohol... more Hydrogen bonding between poly(methyl vinyl ether-co-maleic acid) (PMVE–MA) and poly(vinyl alcohol) (PVOH) has resulted in films with lower oxygen transmission rates (OTR) than pure PVOH. In the range 20–30% (w/w) PMVE–MA, complexation between the two polymers in the blend was maximized, as shown by viscometry, Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) analysis. OTR measurements have shown
A commercial layered double hydroxide (LDH) with nominal composition was intercalated with lauric... more A commercial layered double hydroxide (LDH) with nominal composition was intercalated with lauric and stearic acid using a surfactant-assisted method. X-ray diffraction, thermal analysis and infrared spectroscopy confirmed that bilayer-intercalated compounds were ...
Raman spectra of synthetic “braggite” (Pt, Pd, Ni)S with variable Pt/Pd ratios (atomic ratios bet... more Raman spectra of synthetic “braggite” (Pt, Pd, Ni)S with variable Pt/Pd ratios (atomic ratios between 0.31 and 1.37) and saturated in Ni (up to 1.99 atomic %) have been recorded and compared with the Raman spectra of synthetic “cooperite” and the pure palladium and platinum sulfides. In order to obtain more information on the significant differences in the spectra of these synthetic samples, factor group analyses of “braggite” and “cooperite” have been performed.
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