Sulphate admixtures

Air-entraining admixtures, therefore, produce concrete which is more durable to conditions of freezing and thawing, particularly in the presence of de-icing salts, more resistance to sulphate attack, provides better protection to embedded reinforcement and is more tolerant of poor curing conditions. There appears to be no... 

Few comprehensive classification schemes for CCP exist. The American Society for Testing and Materials (ASTM 1994) classifies two catgories of fly ash (Class F and Class C) based upon chemical and physical properties of the fly ash (the total amount of Si + A1 + Fe, sulphate, loss on ignition). This classification system was developed for the use of fly ash as an admixture in concrete. More recently, new classification schemes have been developed that place emphasis on textural descriptions, the form of carbon (or char ), and the surface properties of fly ash (Hower Mastalerz 2001). These new classification schemes for fly ash may be the result of growing concern over mercury emissions from coal-fired boilers. Studies have shown that mercury adsorption onto the surface of fly ash particles is a function of both the total carbon content and the gas temperature at the point of fly ash collection (Hower et al. 2000). 

Investigations showed that the salts of other alkali metals are not so efficient in suppressing secondary flame as potassium salts. Fairly numerous experiments were carried out to clear up whether or not known antiknock substances, such as tetraethyl lead or nickel carbonyl prevent the development of a secondary flame. They proved to have no effect on its development. In practice, two methods for removing gun-flash may be employed, i.e. either a special flashless powder is produced, containing nitroguanidine or DNT and a small admixture of potassium sulphate,... 

Dr. Bostock s summary is as follows In order to procure an ink which may he little disposed either to mould or to deposit its contents, and which, at the same time, may possess a.deep.black hue not liable to fade, the gells should be macerated for some hours in hot water, and the fluid, filtered tire filtrate should, be then exposed for about fourteen, days to a warm atmosphere, when any fungoid growth that may be observed must, be removed. A solution of sulphate of iron is to be. employed which has been boiled, or. exposed for some time, to the air, and in which there is consequently an admixture of sesquioxide of iron.. If the infusion of galls be made considerably stronger than is generally directed, the ink formed in this manner will not necessarily require the addition of a mucilaginous substance to render it of a proper consistence. 

Hungary, and in otlior mineral waters, though not in sufficient quantities to remunerate for its extraction. Kuulmann and Vogel found it in admixture with the sulphate of tire same base in an efflorescence on the wails in several towns, and considered its production to be owing partly to the presence of soda salts in the limestone used in the preparation of the mortar, and parity to the soda in the coal with which the limestone had been burned. In plants growing on the eea-ahore oxalate of soda exists, and when these are burned, the oxalate, losing carbon io oxide, becomes carbon a ta. 

The sulphate of lime, in contact with incandescent charcoal, yields its oxygen to the latter element, and carbonic oxide, or a mixture of this and carbonic acid is evolved, leaving protosulphide of calcium in admixture with the carbonate of soda previously prodaced,... 

The initial raw material should contain the minimum impurities and admixtures of sulphates, calcium and magnesium salts. A sodium chloride solution is applied in a saturated state potassium chloride solutions are generally unsaturated to prevent the danger of the pipes becomming clogged at an unexpected cooling of the solution as the solubility of this salt depends to a considerable degree upon the temperature. 

The concentration of the water of certain mineral springs and of the ocean also affords a means of isolating salt. Less soluble constituents, such as calcium sulphate, separate first. Admixture of the salt with more soluble compounds, such as magnesium chloride, is obviated by not carrying the concentration too far. Shipper4 states that the elimination of potassium chloride can be effected by repeated crystallization of the salt from water. 

Methyl chlorosulphonate was employed by the Germans both alone, and in admixture with dimethyl sulphate (75 parts dimethyl sulphate and 25 parts methyl chlorosulphonate) under the name of C-Stoff. ... 

Fig. 9. Decreasing values of SF(C3-nC5) accompanied by increasing levels of H2S in gas-condensates are attributed to thermochemical sulphate reduction. Concomitant increase in SF(C3- Cs) and H2S in oils is postulated to be due to admixture of H2S-bearing gas-condensate.

Chemical deterioration of water quality is caused by admixtures of soUd, Uquid or gaseous phases which are water-soluble. These particularly include free acids, nitrates, chlorides, sulphates, salts of heavy metals, cyanides and phenols, and gaseous substances. Such substances can entirely destroy biological revival and the self-purification capability of the stream as a consequence of exhaustion of dissolved oxygen from water [12-16]. 

Copper sulphate, pentachlorophenol and other chemicals are sometimes used as admixtures to concrete to prevent fungus growth. Satisfactory results are difficult to guarantee as fungicides tend to wash out and lose effectiveness with time. The toxicity of such materials must also be taken into consideration,... 

According to Hanehara and Yamada [360] the adsorption of carboxylate admixtures is influenced by sulphate ions too and is diminishing with SO concentration increasing. In Fig. 6.104 the effect of sulphate ions on the flow surface area at various number of carboxylate groups in a track chain of PC is shown. 

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