Cement composition

Cement clinker Cement-composites Cement copper Cemented carbide... 

From the beginning of this century, the demand for asbestos fibers grew in a spectacular fashion for numerous applications, in particular for thermal insulation in steam engines and technologies (4). Moreover, the development of the Hatschek machine in 1900 for the continuous fabrication of sheets from an asbestos—cement composite opened an important field of industrial application for asbestos fibers. 

The reinforcing capacity of asbestos fibers in a cement matrix constitutes another key criteria for the evaluation of asbestos fibers. This property is assessed by preparing samples of asbestos —cement composites which, after a standard curing period, are tested for flexural resistance. The measured mpture modub are converted into a parameter referred to as the fiber strength unit (FSU) (34). 

Fig. 1. Phase equilibria ia the C—A—S (CaO—AI2O2—Si02) system (3,4) temperatures are ia °C. Shaded areas denote two Hquids compositional index marks on the triangle are indicated at 10% intervals B denotes cristobaUte [14464-46-17, and D denotes tridymite [15468-32-3] both of Si02 composition E is anorthite [1302-54-17, Al2CaSi20g G is muUite [55964-99-3]-, H, gehlenite [1302-56-3], Ca2Al2Si02 and J is the area of Pordand cement compositions.

Fig. 2. Cement 2ones in the CaO—AI2O2—Si02 system (5) where B represents basic blast-furnace slag D, cement compositions which dust on cooling E, compositions showing no tendency to set G, aluminous cement and PC, Pordand cement.

One approach for ameliorating the highly brittle nature of these cements has involved the use of tougher, more ductile fillers (62,63). Another approach for improving the overall properties of traditional glass—ionomer cements involves the development of hybrid cement-composites and resin-modified cements (64—68). 

E.I. Du Pont de Nemours, Colloidal stable solvent cement compositions comprising chloro-prene polymers, phenolic resins and polyisocyanate, U.S. Patent 3,318,834, 9 May, 1967. 

Figure 22 Influence of fiber content on flexural strength and fracture toughness of (O) softwood-cement composites and ( ) hardwood-cement composites (air-cured) [78].

Cellulose cement composites show a similar sensibility to humidity (Table 14), as do plastic composites, that is, they show a decrease of mechanical properties. Yet, formerly reached values can again be achieved by a drying process on the composite [75]. 

Cement composition tops have about the same properties as natural stone but at a lower cost. They have a more even appear-... 

Tops made from solid epoxy compounds are resistant to just about any kind of chemical abuse but are very expensive. They are often sold with an integral backsplash and curved junction, which makes cleaning easy. They are much easier on glassware than either stone or cement composition. 

The last stage in the development of the EBA cement is represented by the polymer cements. Brauer Stansbury (1984b), taking advantage of the fact that the EBA-HV liquid does not inhibit vinyl polymerization, included methacrylates into the cement composition. The object was to produce a material that set after mixing, both by polymerization and by salt or chelate formation. 

A polymeric composition for reducing fluid loss in drilling muds and well cement compositions is obtained by the free radical-initiated polymerization of a water-soluble vinyl monomer in an aqueous suspension of lignin, modified lignins, lignite, brown coal, and modified brown coal [705,1847]. The vinyl monomers can be methacrylic acid, methacrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, vinylacetate, methyl vinyl ether, ethyl vinyl ether, N-methylmethacrylamide, N,N-dimethylmethacrylamide, vinyl sulfonate, and additional AMPS. In this process a grafting process to the coals by chain transfer may occur. 

Similar copolymers with N-vinyl-N-methylacetamide as a comonomer have been proposed for hydraulic cement compositions [669]. The polymers consist of AMPS in an amount of 5% to 95%, vinylacrylamide in an amount of 5% to 95%, and acrylamide in an amount of 0% to 80%, all by weight. The polymers are effective at well bottom-hole temperatures ranging from 200° to 500° F and are not adversely affected by brine. Terpolymers of 30 to 90 mole-percent AMPS, 5 to 60 mole-percent of styrene, and residual acrylic acid are also suitable for well cementing operations [253]. 

An N-vinylpyrrolidone/acrylamide random copolymer (0.05% to 5.0% by weight) is used for cementing compositions [371, 1076]. Furthermore, a sulfonate-containing cement dispersant is necessary. The additive can be used in wells with a bottom-hole temperature of 80° to 300° F. The fluid loss additive mixture is especially effective at low temperatures, for example, below 100° F and in sodium silicate-extended slurries. 

Adding low-density materials reduces the density of a cement composition. These additives are referred to as extenders, because they reduce the demand of... 

Foam cement is a special class of lightweight cement. The gas content of foamed cement can be up to 75% by volume. The stability of the foam is achieved by the addition of surfactants, as shown in Table 10-9. A typical foamed cement composition is made from a hydraulic cement, an aqueous rubber latex in an amount up to 45% by weight of the hydraulic cement, a latex stabilizer, a defoaming agent, a gas, a foaming agent, and a foam stabilizer [359,362]. Foamed high-temperature applications are based on calcium phosphate cement [257]. 

J. F. Baret, B. Dargaud, J. Villar, and M. Michaux. Cementing compositions and application of such compositions to cementing oil (or similar) wells. Patent CA 2207885, 1997. 

V. Barlet-Gouedard and P. Maroy. Cementing compositions and application thereof to cementing oil or analogous wells. Patent WO 9901397,1999. 

J. L. Boles and J. B. Boles. Cementing compositions and methods using recycled expanded polystyrene. Patent US 5736594, 1998. 

D. L. Bout and J. D. Childs. Foamed well cementing compositions and methods. Patent US 5133409, 1992. 

B. G. Brake and J. Chatteiji. Fluid loss reducing additive for cement compositions. Patent EP 595660,1994. 

L. E. Brothers. Method of reducing fluid loss in cement compositions containing substantial salt concentrations. Patent US 4640942, 1987. 

L. E. Brothers. Low temperature set retarded well cement compositions and methods. Patent US 5472051, 1995. 

L. E. Brothers, D. D. Onan, and R. L. Morgan. Well cement compositions containing rubber particles and methods of cementing subterranean zones. Patent US 5779787,1998. 

R. Carpenter and D. Johnson. Method and cement-drilling fluid cement composition for cementing a wellbore. Patent WO 9748655, 1997. 

R. B. Carpenter, J. B. Bloys, and D. L. Johnson. Cement composition containing synthetic hectorite clay. Patent WO 9902464,1999. 

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