Portland cement composition

Could the waste from a fluidized-bed limestone/coal furnace (Section 8.5) be used in Portland cement composites What possible problem(s) might arise ... 

Fig. 10.8 Setting times of neat pastes of mixtures of Ciment Fondu and Portland cement. These are only general indications, as the times depend on Portland cement composition, mixing time, temperature and other factors. After Robson (R47).

Acrylic latices have been used successfully for more than 35 years to modify portland cement composites. The use of solid grade acrylic cement modifiers has become common during the past few years. Both of these types will be discussed later in this section. The level of polymer modification is measured as a ratio of polymer solids by weight of cement. A 15%-20% modification represents the range for optimum performance lower modification levels may prove acceptable for certain product applications (Rohm Haas, 1989). 

Calculate the heats of hydration after three days, H(3d), and one year, H yr), for the following Portland cement compositions, (wt%) ... 

Dow Latex 560 for Portland Cement Compositions, Dow Oiemical Co., Midland, Michigan (1959)... 

Bye, G.C., Portland Cement Composition, Production, and Properties, 1st ed., Pergamon Press, Oxford, 1983, 149 pp. 

Aziz MA, Paramasivam P, Lee SL et al (1981) Prospects for natural fibre reinforced concretes in construction, hit J Cement Compos Lightweight Ctmciete 3 123-132 Juarez C, Duran A, Valdez P, Fajardo G et al (2007) Performance of Agave lecheguilla natural fibre in Portland cement composites exposed to severe environment conditions. Build Environ 42 1151-1157... 

Table 19.2 Effect of natural fiber treatments on properties and durability of Portland cement composites. (Tmeans that property increased, >lmeans that property decreased). 

Coatings of this type consist of a calcium aluminate based cement and various inert ingredients and are supplied in powder form to be mixed with water when used. They may be applied by casting, pouring, or guniting. Calcium aluminate based coatings are hydraulic and consume water in their reaction mechanism to form hydrated phases. This is similar to Portland cement compositions however,... 

Jet Set or regulated-set cement is a modified portland cement composition capable of developing a high early set strength upon hydration. The cement consists essentially of portland cement and from about... 

Portland cement is classified as a hydrauHc cement, ie, it sets or cures in the presence of water. The term Portland comes from its inventor, Joseph Aspdin, who in 1824 obtained a patent for the combination of materials referred to today as Portland cement. He named it after a grayish colored, natural limestone quarried on the Isle of Portland, which his cured mixture resembled. Other types of hydrauHc cements based on calcium materials were known for many centuries before this, going back to Roman times. Portland cement is not an exact composition but rather a range of compositions, which obtain the desired final properties. The compounds that make up Portland cements are calcium siHcates, calcium aluminates, and calcium aluminoferrites (see ). 

Portland cement is manufactured by two basic processes, the wet process and the dry process. The dry process uses approximately 25% less energy per ton of Portland cement and is used to produce about 68% of the U.S. Portland cement. Both processes start by mixing selected raw materials, cmshed and/or milled to approximately s in. (1.9 cm) diameter, in the correct ratios to give the final desired chemical composition. 

Special purpose and blended Portland cements are manufactured essentially by the same processes as ordinary Portland cements but have specific compositional and process differences. White cements are made from raw materials of very low iron content. This type is often difficult to bum because almost the entire Hquid phase must be furnished by calcium aluminates. As a consequence of the generally lower total Hquid-phase content, high burning-zone temperatures may be necessary. Past cooling and occasionally oil sprays are needed to maintain both quaHty and color. 

ASTM C845 Type E-I (K) expansive cement manufactured ia the United States usually depends on aluminate and sulfate phases that result ia more ettriagite formation duriag hydration than ia normal Portland cements. Type K contains an anhydrous calcium sulfoaluminate, C A SI. This cement can be made either by iategraHy burning to produce the desired phase composition, or by intergrinding a special component with ordinary Portland cement clinkers and calcium sulfate. 

Cement. Portland cement, a mixture of calcium siUcate and calcium aluminate minerals, is produduced by the calcination of argillaceous limestone or mixtures of limestone and clay (see Cement). Although other clays can be used, ka olin is preferred because of its alumina and siUca content and low level of impurities. It is especially desirable in the manufacture of white cement and other types requiring careful control of chemical composition. Air-floated ka olin, because of its low cost, is usually used. 

Concrete is a particulate composite of stone and sand, held together by an adhesive. The adhesive is usually a cement paste (used also as an adhesive to join bricks or stones), but asphalt or even polymers can be used to give special concretes. In this chapter we examine three cement pastes the primitive pozzolana the widespread Portland cement and the newer, and somewhat discredited, high-alumina cement. And we consider the properties of the principal cement-based composite, concrete. The chemistry will be unfamiliar, but it is not difficult. The properties are exactly those expected of a ceramic containing a high density of flaws. 

There are less exotic ways of increasing the strength of cement and concrete. One is to impregnate it with a polymer, which fills the pores and increases the fracture toughness a little. Another is by fibre reinforcement (Chapter 25). Steel-reinforced concrete is a sort of fibre-reinforced composite the reinforcement carries tensile loads and, if prestressed, keeps the concrete in compression. Cement can be reinforced with fine steel wire, or with glass fibres. But these refinements, though simple, greatly increase the cost and mean that they are only viable in special applications. Plain Portland cement is probably the world s cheapest and most successful material. 

C03-0081. Portland cement contains CaO, Si02, AI2 O3, and FC2 O3. Calculate the mass percent composition of each compound. 

The commercial product is actually a blend of different cements. This blending leads to a more constant quality. The chemical composition of Portland cement is typically 60% to 69% CaO, 18% to 24% Si02, 4% to 8%... 

Small amounts of phosphonium complexone [1560] are sufficient to increase adhesion to the stratal rock. Table 18-4 illustrates an example for plugging solution with Portland cement and phosphonium complexone. Calcium chloride acts as a regulator of the setting time in the suggested composition. More precisely, phosphonium complexone stands for certain chelating phosphorous compounds (e.g., oxyethylidene diphosphonic acid, nitrilo-trimethyl phosphonic acid, sodium tripolyphosphate, or amiphol) [1540]. The mixture is applicable at low temperatures from 20° to 75° C. 

V. Kh. Dulaev, N. M. Bondarets, N. A. Polukhina, V. I. Petresku, R. G. Galiev, P. P. Kapustin, and O. S. Matrosov. Composition for preparation of aerated plugging solution—contains Portland cement, oxyethylated monoalkylphenol(s) of propylene trimers, glycol mixture, air, water, etc. Patent SU 1745893-A, 1992. 

V. R. Negomedzyanov, V. P. Bortsov, V. S. Denisov, V. V. Slepov, and S. S. Volkova. Plugging composition for use in oil and gas extraction industry—contains Portland cement and aluminium-containing additive in form of slag dust waste from aluminium production process. Patent RU 2029067-C, 1995. 

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