How to use Cements in a sentence
We have here the two classes into which hydraulic cements are divided.
Zinc chloride solution readily dissolves the oxide with the formation of oxychlorides, some of which are used as pigments, cements and for making artificial teeth.
Its materials are pebbles, clays and sands of various' colours from white to deep red, tinged with peroxide of iron, which sometimes cements the pebbles and sands into compact rocks.
On account of its refractory nature, it is employed in the manufacture of crucibles, furnace linings, &c. It is also used in making hydraulic cements.
It is employed in the manufacture of cements.Advertisement
Other matrices are slag cement, a comparatively recent invention, and some other natural and artificial cements which find occasional advocates.
The matter was carefully investigated, and it was found that the sulphate of magnesia in the sea-water has a decomposing action on Portland cements, especially those which contain a large proportion of lime or even of alumina.
The simplest of all pozzuolanic cements would be a mixture of pure lime and hydrated silica, but though the latter is prepared artificially for various purposes, it is too expensive to be used as a cement material.
Pozzuolanic cements are little used in England.
Cements of the Portland type differ in kind from those of the pozzuolanic class; they are not mechanical mixtures of lime and active silica ready to unite under suitable conditions, but consist of definite chemical compounds of lime and silica and lime and alumina, which, when mixed with water, combine therewith, forming crystalline substances of great mechanical strength, and capable of adhering firmly to clean inert material, such as stone and sand.Advertisement
The earliest forms of cements of the Portland class were the hydraulic limes.
The following analysis may be taken as typical of cements made from chalk and clay on the Thames and 100.0 There may be variations from this composition according to the nature of the raw materials employed.
The chief use of hydraulic cements, whether of the pozzuolanic or Portland class, is to act as an adhesive material in work which is to be exposed to water.
On this observation rests the whole of the present enormous employment of hydraulic cements.
It might be supposed that hydraulic cements from their nature would be indifferent to the action of water, but this is only true if the structures of which they form part are sufficiently compact.Advertisement
Under this term are comprehended all cements whose setting properties primarily depend on the hydration of calcium sulphate.
This may be almost chemically pure, when it is generally used for Keene's cement; or it may contain smaller or greater quantities of impurities, in which case it is suitable for the preparation of cements of the plaster of Paris class.
All cements having calcium sulphate as their base are suitable only for indoor work because of the solubility of this substance.
Cements such as marine glue are solutions of shellac, india-rubber or asphaltum in benzene or naphtha.
For use with wood which is exposed to moisture, as in the case of wooden cisterns, a mixture may be made of 4 parts of linseed oil boiled with litharge, and 8 parts of melted glue; other strong cements for the same purpose are prepared by softening gelatine in cold water and dissolving it by heat in linseed oil, or by mixing glue with one-fourth of its weight of turpentine, or with a little bichromate of potash.Advertisement
In addition to its extensive use in soap-making, rosin is largely employed in making inferior varnishes, sealing-wax and various cements.
Glycerin acts as a preservative against decomposition, owing to its antiseptic qualities, which also led to its being employed to preserve untanned leather (especially during transit when exported, the hides being, moreover, kept soft and supple); to make solutions of gelatin, albumen, gum, paste, cements, &c. which will keep without decomposition; to preserve meat and other edibles; to mount anatomical preparations; to preserve vaccine lymph unchanged; and for many similar purposes.
The term is often applied to adhesive mixtures employed to unite objects or parts of objects (see below), but in engineering, when used without qualification, it means Portland cement, its modifications and congeners; these are all hydraulic cements, i.e.
You won't find any primary colors, but you will find bold stones, cements, khakis, and even some purples.
Be that as it may, scientists recently discovered 4,000-year-old noodles in China, which firmly cements China as the originator of the noodle.Advertisement
This loyalty is another common ground they share and another area that cements their relationship.
Litharge is much used for the preparation of lead salts, for the manufacture of oil varnishes, of certain cements, and of lead plaster, and for other purposes.
The term Natural Cements is applied to cements made by burning mixtures of clay and carbonate of lime naturally occurring in approximately suitable proportions.
They may be regarded as badly-mixed Portland cements, and need no special description.
The principles which govern the preparation and setting of the other class of calcium sulphate cements, that is, cements of the Keene class, are not fully understood, but there is a fair amount of knowledge on the subject, both empirical and scientific. The essential difference between the setting of Keene's cement and that of plaster of Paris is that the former takes place much more slowly, occupying hours instead of minutes, and the considerable heating and expansion which characterize the setting of plaster of Paris are much less marked.
It has been shown that the best hydraulic lime, or volcanic puzzuolana and lime, if properly ground while slaking, and otherwise treated in the best-known manner, as well as some of the so-called natural (calcareous) cements, will yield results certainly not inferior to those obtained from Portland cement.
American "natural" cements are of a somewhat different class.