A5066581334- Concrete and Cement Materials Research
- Clay minerals and soil interactions
- Zeolite Catalysis and Synthesis
- Crystal Structures and Properties
- Chemical Synthesis and Characterization
- Glass properties and applications
- Magnesium Oxide Properties and Applications
- Mineralogy and Gemology Studies
- Building materials and conservation
- Grouting, Rheology, and Soil Mechanics
- Geological and Geochemical Analysis
- X-ray Diffraction in Crystallography
- CO2 Sequestration and Geologic Interactions
- Recycling and utilization of industrial and municipal waste in materials production
- Concrete Properties and Behavior
- Innovative concrete reinforcement materials
- Methane Hydrates and Related Phenomena
- Layered Double Hydroxides Synthesis and Applications
- Minerals Flotation and Separation Techniques
- Concrete Corrosion and Durability
- Advanced ceramic materials synthesis
- Solid-state spectroscopy and crystallography
- Metal Extraction and Bioleaching
- Thermal and Kinetic Analysis
- Drilling and Well Engineering
King's College London
2023-2024
University of Manchester
2019-2023
University of St Andrews
2023
University of Essex
2023
University of Bristol
1998-2023
University of Edinburgh
1948-2022
University of Pisa
2004
Imperial Valley College
1993
University of Aberdeen
1979-1991
American Ceramic Society
1980-1986
Calcium silicate hydrate gel is a very poorly crystalline material that the main product of reaction portland cement with water. Evidence presented for disordered layer structure, in which most layers are structurally imperfect ones jennite (Ca 9 Si 6 O 32 H 22 ), and others similarly related to 1.4‐nm tobermorite 5 26 18 both structures being modified by omission many their tetrahedra. The evidence comprises conditions formation, anion type, Ca/Si ratio, 2 O/Ca ratios densities various...
Summary Three groups of minerals are discussed, which typified by pyroaurite and sjögrenitc, hydrocalumite, ettringite. All show interesting structural features. In the pyroaurite-sjögrenite group, brucite-likc layers carrying a net positive charge alternate with in oxygen atoms carbonate water molecules statistically distributed on single set sites; other anions may replace carbonate, especially synthetic phases. Hydrocalumite related phases also have layer structures positively charged...
ETTRINGITE (Ca6[Al(OH)6]2(SO4)3.26H2O) occurs as a natural mineral, and is technically important hydration product of Portland supersulphated cements in its use, satin white, for coating paper. It forms hexagonal, prismatic crystals which synthetic material are often highly elongated. Bannister, Hey Bernal1 obtained unit-cell data (hexagonal: 11.26, c 21.48 A, space group P63/mmc, Z = 2). No crystal structure determination based on single evidence has been reported, but Welin2 determined the...
H. F. W. Taylor, J. Chem. Soc., 1950, 3682 DOI: 10.1039/JR9500003682
Summary The crystal structures of sjögrenite and pyroaurite, two stacking modifications approximate composition Mg 6 Fe 2 (OH) 16 (CO 3 ).4H O, have been determined by X-ray diffraction using three-dimensional methods. Sjögrenite is hexagonal, with a 3·13, c 15·66 Å, space group P6 /mmc , Z = ¼; pyroaurite rhombohedral, H 23·49 R 3̄ m or ⅜. Both are based on brucite-like layers, magnesium iron distributed among the octahedral positions. cations appear to be largely disordered, although...
Synopsis A method is described for predicting the sodium, potassium and hydroxyl ion concentrations in pore solutions ofhydrated OPC or Portland-pfa (pulverized-fuel ash, fly ash) concretes, mortars pastes more than about 1 day old. The minimum data required are total Na 2 O K contents of Portland cement component pfa, if present, relative amounts cement, pfa water, age. Other data, especially water-soluble may be introduced with advantage. calculation, which rests on principle mass balance...
Summary A specimen from Långban, Sweden, was found to consist largely of sjögrenite in which segregation and ordering the metal cations had occurred, yielding an intergrowth regions two main types with compositions probably or near Mg 2/3 Fe 1/3 (OH) 2 (CO 3 ) 1/6 (H O) 0·4 12/13 1/13 1/26 0·8 . To a smaller extent proceeded further, giving approximating end-member Mg(OH) .H O. It is suggested that names pyroaurite be used for 2H- 3R- polytypes this structure irrespective Mg:Fe ratio,...
The Bogue calculation gives low results for alite and inaccurate ones the other phases in Portland cement clinkers, largely because compositions of differ markedly from those unsubstituted compounds which it assumes to be present. For a wide range rapidly cooled clinkers produced modern plants, are sufficiently constant justify use, with minor modifications, average values based on X-ray microanalyses, instead compounds. On this basis, procedure is described which, like calculation,...
Summary This process has been reinvestigated, mainly with X-rays, using an FeO-containing, fibrous variety (nemalite), and also a nearly pure specimen. The results confirm that the transformation is oriented, c - -directions of brucite becoming normals to (111) (11̄0) in periclase. There intermediate, spinel-like stage; spinel -axis parallel to, twice as long as, stage especially prominent when nemalite heated air or nitrogen, but shown by material. shows further intermediate under certain...
The first page of this article is displayed as the abstract.
Cement pastes were cured at 80°C and examined by scanning electron microscopy, X-ray microanalysis diffraction immediately or after storage in water for various periods 20°C. Ettringite began to form a few days the heat treatment, as very small crystals thinly dispersed throughout paste close admixture with C-S-H. It subsequently recrystallized cavities typically 5-10μm size formed dissolution of clinker grains other ways. There no indications that this latter process disrupted surrounding...
Summary Tobermorite minerals vary in some proper lies, notably whether or not unidimensional lattice shrinkage occurs by about 300 °C to give a 9·3 form; specimens that do this are called normal, and ones not, anomalous. Data compared for thirteen natural tobermorites the extent which normal anomalous character is related other properties examined. The most definite correlations found with chemical composition morphology. conditions of formation discussed light synthetic evidence.