The gypsum anhydrite rocks in the abandoned quarry at Dingwall Nova Scotia Canada are subjected to physical and chemical weathering including hydration of the anhydrite its transformation into secondary gypsum under the influence of water This process is known to lead to the localized volume increase of the rock and the formation of spectacular hydration
This paper reports on the hydration and properties of composite binders with 20 70% blastfurnace slag and 50 70% calcium sulphate commercial hemihydrate or waste anhydrite cured for up to
An example of a hydration reaction is when anhydrite CaSO 4 is transformed into gypsum CaSO 4 ·2H 2 O A consequence of hydration is that the resulting mineral has a greater volume than the original mineral In the case of the Mosul Dam hydration of anhydrite has important consequences The increase in volume applied force to an overlying
At lower temperatures the hydration speed of anhydrite is much higher and a slow hydration of pure anhydrite can be observed Diagram 3 Heat of hydration of hemihydrate The third type of diagram that needs to be understood is the heat of hydration of hemihydrate The heat of hydration is measured with heat flow calorimetry
Hydration of anhydrite to gypsum gypsification of anhydrite in the weathering zone sometimes causes a volume increase This can lead to local detachments of the surface layer of the weathering anhydrite rocks and creation of the hydration cavities and rare hydration caves or swelling caves; German Quellungshöhlen inside domes formed by the uplifted layer
DOI / Corpus ID 54834109; Hydration of anhydrite of gypsum in a ball mill article{Sievert2005HydrationOA title={Hydration of anhydrite of gypsum in a ball mill} author={Thomas Sievert and Albrecht Dr Wolter and Nakshatra Bahadur Singh} journal={Cement and Concrete Research} year={2005} volume={35}
X ray analysis and DTA have been used to identify the hydration products interpret the strength data and to compare the plaster of Paris activated cement with anhydrite activated slag cement
Wolf et al [41] found that when the lithium carbonate content is less than wt % of the cement the total hydration heat released from ternary CSA OPC anhydrite mixtures can be improved in
Upon adding activators of anhydrite hydration K2SO4 or Na2SO4 XRD and IR spectral analysis data show that the specimens after 1 day of phosphoanhydrite hydration with additives contained
The activators K2SO4 and Na2SO4 had a large effect on the hydration of anhydrite binder at its early age up to 3 days in comparison with the anhydrite binder without activators
The addition of CaCO 3 and CaSO 4 to Portland cement clinker influences the setting behaviour the progress of hydration and the strength development during hydration If limestone is added in the small quantities limestone has a positive impact on the engineering properties of the cement and concretes [1] The positive impact of limestone on the cement
The effect of K2SO4 activator on the hydration of chemical anhydrite obtained from burned FGD gypsum has been studied by different experimental techniques Results obtained show that the degree of hydration increases when the K2SO4 concentrations increase from to wt% Their heat evolution rate and maximum value also increase with the
DOI / Corpus ID 212836166; Impact of varying Li2CO3 additions on the hydration of ternary CSA OPC anhydrite mixes article{Wolf2020ImpactOV title={Impact of varying Li2CO3 additions on the hydration of ternary CSA OPC anhydrite mixes} author={Julian Johannes Wolf and Daniel Jansen and Friedlinde Goetz Neunhoeffer and
OPC/CSA ratios on the hydration products and strength development have been inves tigated in some research works With regard to the hydration products it was reported that [1 28] when the OPC proportion in ternary composite systems is lower than 40% C4A3S is given priority in the hydration process In the absence of OPC ettringite is formed
At 30% calcium oxide and no anhydrite additions the hydration products stratlingite and hydrotalcite with the card number of 29 0285 Ca 2 Al 2 SiO 7 ·8H 2 O and 89 0460 Mg Al OH 2 CO 3 H 2 O respectively could be detected in MC paste after 3 d which could not be detected for calcium oxide anhydrite
OPC/CSA ratios on the hydration products and strength development have been inves tigated in some research works With regard to the hydration products it was reported that [1 28] when the OPC proportion in ternary composite systems is lower than 40% C4A3S is given priority in the hydration process In the absence of OPC ettringite is formed
The influence of sodium oxalate on anhydrite hydration process and crystal morphology of its dihydrate products was studied by determination of the hydration rate hydration temperature and ion
The effects of calcination and modification on the morphology shapes and textures and crystal structure of anhydrite powders were studied The results show that calcination at 100°C causes anhydrite to disintegrate into smaller crystals accompanied by a slight increase in d spacing Without calcination and modification the solidification time and
lm to few cm The shape and size of the anhydrite par ticles and layers are important for the specific surface of anhydrite and thus for the evolution of its hydration over time The mineral transformations in the anhydrite gypsum water system take place via the solution phase anhydrite dissolves in the pore water; gypsum precipitates
Hydration experiments of natural anhydrite in a ball mill with water and activator solutions such as H 2 SO 4 pH 1 5 % MgSO 4 ·7H 2 O and solution of calcium hydroxide as a function of time
The mechanism of anhydrite dissolution proceeds first by hydration of anhydrite CaSO 4 to gypsum CaSO 4 ·2H 2 O and then dissociation of gypsum to sulfate SO 4 2 and calcium Ca 2 ions in the water [97] However other researchers argued that the dissolution proceeds via diffusion
Depending on the amount of anhydrite different calcium sulfoaluminate hydrates have been produced during the hydration when a very low amount of anhydrite has been used as in sample C93 S7 L0 the diffraction patterns have been dominated by monosulfate peaks at ° 2θ reflection 003 and hydroxy AFm as well as C 3 AH 6
The mechanism of anhydrite dissolution proceeds first by hydration of anhydrite CaSO 4 to gypsum CaSO 4 ·2H 2 O and then dissociation of gypsum to sulfate SO 4 2 and calcium Ca 2 ions in the water [97] However other researchers argued that the dissolution proceeds via diffusion
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