Hydrate characteristics

The hydration characteristics of cement (rate and extent) are of great importance in the end product. Silica is known to react relatively fast in the cement system. 

Properly used, a saturated salt sensor is accurate to 1 C between dew point temperatures of -12 and +38°C. Outside Ihtfse limits, small errors may occur ns a result of the multiple hydration characteristics of lithium chloride, which may produc d ambiguous results at 4I C. 12 C. 

We have employed these dielectric techniques to study the hydration characteristics of hydrocolloids widely used in food systems 153]. 

We have now established sufficient background to consider briefly the kinetics of reactions in water where apolar solutes are involved. For example, if the hydration characteristics of t-butyl alcohol in water are controlled to a marked extent by the hydration of the apolar t-butyl group, then it is likely that the same state of affairs exists for, say t-butyl chloride and other alkyl halides and related compounds in water. In other words, the hydration properties can be characterized by the general statement that, in the solvent co-sphere, water-water interactions > water-solute interactions, but that in the activation process water-solute interaction will increase. Since for apolar solutes, Cp3 > 0, and assuming that in the transition state, Cp3 0, then a tentative prediction is that ACp < 0 and — —Cp3. 

Campbell, S. D., Kraning, K. K., Schibli, E. G. and Momii, T. Hydration characteristics and electrical resistivity of stratum comeum using a noninvasive four-point microelectrode method. J. Invest. Dermatol. 69 290, 1977. 

Filtrol SR catalyst is relatively immune to sulfur poisoning (326), possibly because of the much lower iron content or because of some difference in hydration characteristics. Silica-magnesia under some conditions is poisoned by sulfur compounds, but the normal concentrations of steam that prevail in commercial units appear adequate to avoid this difficulty (100). 

Si NMR has also been applied to a hydration study of actual Portland cements, the broad spectra of which are composed of the spectra of the component tricalcium silicate and p-dicalcium silicate (Figure 4.40) (Barnes et al. 1985). Integration of the Si spectra of the discrete cement silicates and Portland cement hydrated under identical conditions allowed a comparison of the hydration characteristics (Figure 4.41) and... 

Because of the above complexities, before deciding to invest in a hydrating plant, the hydration characteristics of the available grades of quicklime should be evaluated. The quality of the water supply should also be assessed, bearing in mind any seasonal variations. 

The mean apparent density depends on both the porosity of the parent limestone and the degree of burning of the lime. Thus, a quicklime produced from a porous limestone may have a similar reactivity to one made from a dense limestone, but different hydration characteristics. 

Parvathy K. S., Susheelamma N. S., Tharanathan R. N. 2007. Hydration characteristics of guar gum samples and their fractions. Food Hvdrocolloids. 21. 630-637. 

It should be pointed out that the BCF theory was derived for crystal growth from the vapour and while it should also apply to growth from solutions (and melts), it is difficult to quantify the relationships because of the more complex nature of these systems. Viscosities, for example, are higher and diffusivities lower in solutions ( 10 Nsm (1 cP) and 10 m s ) than in vapours ( 10 Nsm and lO m s" ). In addition, the dependence of diffusivity on solute concentration can be complex (section 2.4). Transport phenomena in ionic solutions can be complicated, especially if the different ions exhibit complex hydration characteristics. Furthermore, little is known about surface diffusion in adsorbed layers, and ion dehydration in or near these layers must present additional complicating factors. 

There is also a high interest in the individual hydration characteristics of metal ions. The study of hydrated metal ions in gas phase provides a connection between the essential chemistry of the isolated ion and that in the solvent. Solvated ions also appear in high concentrations in living organisms, where their presence or absence can fundamentally alter the functions of life. In fact, the structure and... 

El-Didamony, H. et al. (1996) Hydration characteristics of f-C S in the presence of some accelerators. Cement and Concrete Research 26,1179-1187. 

Wang, Y. et al. (1992a) A qnantitative stndy of paste microstructure and hydration characteristics of sulfoalnminate cement, in Proceedings 9th ICCC, New Delhi, Vol. 4, pp. 454M60. 

Yu, Q., Feng, X., and Sugita, S. (1997) Hydration characteristics of 1 lCaO.7Al2O3.CaF2,... 

A chlorine-containing phase similar to belite and designated belinite has also been synthesized (von Lampe et al., 1986 Pradip and Kapur, 1990). It has the chemical formula CagMg[(Si04)4Cl2]. Whereas the hydration characteristics of alinite are superior to those of te, belinite does not hydrate as easily as behte. 

Sharma, K.M. et al. (1997) Hydration characteristics of steel slag in ordinary Portland cement blends, in Proceedings 10th ICCC, Gdteborg, paper 3ii094. 

Guindy, N.M. (1993) Hydration characteristics of lime-siUca pastes. JoMrna/o/77rer/wa/ Analysis 40, 151-157. 

Thus, the difference in the hydration characteristics of silica OX-50 in the aqueous suspension and hydrated powder in different media depends on the particle-particle interactions (distances between particles) and the textural porosity in the powders. Nonpolar (methane) or weakly polar (chloroform) coadsorbates can reduce interaction of water with the silica surface because water-water and water-silica interactions are much stronger than that of water-organics. Therefore, rearrangement of the system organization leads to an increase in the size of water domains with parallel diminution of the contact area between water-organics and water-silica but with increasing silica-organics contact area. 

H NMR spectroscopy (Figure 2.98) was applied by Gran and Hansen (1997) to study a set of cement pastes of different structural and hydration characteristics, the freeze/thaw cycling effects on the pore structure. 

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