Portland applications

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. 

Many of the typical features found in present-day electrostatic precipitators are based on work by W. A. Schmidt. One of his most important applications is the electrostatic precipitator that was installed at the Riverside Portland Cement Company in 1912. This plant handled a gas flow of 470 ni/s at the temperature of 400-500 °C. This was the first precipitator in which thin wire was used as discharge electrode. 

Laurent TC (1998) (ed.) The chemistry biology and medical applications of hyaluro-nan and its derivatives. Portland, London... 

Special grades of gypsum hemihydrate are blended with Portland cement for types with reduced thickening time and setting time. Gypsum requires significantly more water addition. The maximal application temperatures are 70° to 80° C. Sodium silicate is used for cement slurries with diatomaceous earth. It can be used up to 7% by weight. 

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. 

T. C. Laurent, The Chemistry, Biology and Medical Application of Hyaluronan and Its Derivatives. Portland Press, London, 1998. 

IdaTech LLC (formerly Northwest Power Systems), of Bend, Oregon, an Idacorp subsidiary, delivered the first of 110 planned fuel cell systems to the Bonneville Power Administration (BPA), Portland, Oregon in June 2000. The BPA program is part of a fuel cell test and development phase intended to commercialize fuel cell systems for home and small commercial applications by 2003. 

Some of the most common stabilizing agents used in hazardous waste disposal are Portland cement, lime, fly ash, and cement kiln dust. Small quantities of hazardous wastes are disposed of by incineration, energy conversion, manufacture of fuels, or other practical applications. 

Cooper, J. A. and J. G. Watson. Portland Aerosol Characterization Study (PACS). Application of Chemical Mass Balance Methods to the Identification of Major Aerosol Sources in the Portland Airshod. Final report Summary. Prepared for the Portland Air Quality Maintenance Area Advisory Committee and the Oregon Department of Environmental Quality. April 23, 1979. 

Abstract Coal extraction and combustion produce a number of waste streams, some of which can be utilized. Fly ash from the combustion of pulverized coal is characterized it finds application as a partial replacement for Portland cement in concrete. Relatively few uses exist for other wastes, much of which is stockpiled, stored, or landfilled. These leave a legacy for future generations that must be managed to minimize geochemical impacts on air, soil, and groundwater quality. 

Although many Ca-rich fly ashes are self-cementing, strength gain is usually too slow for most practical applications. Moreover, aluminosilicate rich ashes are essentially unreactive with water. The most important application of fly ash is as a partial replacement for Portland cement. In this application, Portland cement furnishes much of the early strength, up to 1 month, while the high alkalinity of cement chemically activates the ash such that its slow reaction with cement components and water contribute increasingly to... 

One of the most significant uses of fly ash is as a mineral admixture in Portland cement concrete. This use alone accounted for over 56 wt% of the fly ash utilized in the USA in 2001 (American Coal Ash Association 2002). Fly ash is particularly well suited to this application because of its... 

Ash from pulverized coal combustion is a strategic material that has many critical applications from a source of aggregate to the most important source of pozzolan for addition to Portland cement concrete. Environmental control measures on the emissions of coal combustion have resulted in a loss of quality for these materials. In response we have seen the advent of beneficiation processes applying both proven and new technologies to produce high-quality consistent products from these materials. Currently we estimate that about one-fifth of all ash products marketed are processed through some form of beneficiation method. We expect that the demand for quality and consistency will continue and the relative amount of process ash products will increase in the future. 

An alternative to silicate-based Portland cement is the calcium aluminate cement, ciment fondu, which originated with the Lafarge company in France in 1908. Ciment fondu is typically made by heating limestone with bauxite, which is mainly AIO(OH) but contains much iron oxide (see Section 17.2). As noted above, calcium aluminate hydrates and hardens much more rapidly than alite, and so ciment fondu, either as such or mixed with Portland cement, can be used whenever a rapidly setting cement is required, for example, for construction at low temperatures. Concretes made from aluminate cements remain serviceable at higher temperatures than Portland cements and so are used to make cast refractories for pyrometal-lurgical applications. 

Applications for sulphur concretes fall into two broad categories utility uses and high corrosion performance uses. Utility applications refer to those for which PC concrete performance is relatively satisfactory, such as parking bumpers, precast curb and gutter, paving slabs and highway median barriers. In these applications in-place economics rather than performance is the criterion that will determine commercial use. As a general rule of thumb, when sulphur and Portland cement are the same price, sulphur concrete should be economically competitive for these applications. 

Sulphur concretes appear well suited for use in environments corrosive to Portland cement concretes. The extensive work by the U.S. Bureau of Mines shows their material performs admirably in such environments. When used as a lining, the initial stress-strain behaviour will allow the material to adapt to the main structural element and relieve internal stresses without cracking. Corrosion resistance will be maintained by the material thereafter, even though the stress strain behaviour alters. On its own, the material retains sufficient strength to withstand typical loads involved in this type of application (eg. liquid container). Sudicrete has not been tested much in this area, although laboratory tests show similar promise. 

Sulfur Impregnation (14). Stronger and more durable products such as Portland cement concrete, ceramic tile and even wood and paper products have been shown to be feasible. In addition, sulfur as an impregnant for fabric liner systems would have application in ponds, holding tanks, etc. 

Sulfur Coatings (1J>, 18). Molten sulfur, often mixed with fibers or modifiers can be used to spray coatings on unbonded block or brick buildings, linings for ponds, portland cement concrete, and other applications where a durable coating is required or useful. 

Other Types of Portland Cements. White Portland cement is standard Type I or III Pordand cement with raw materials selected and controlled to have negligible amounts of iron and manganese oxides, which impart the gray color. The white Pordand cement is used in decorative and architectural applications like precast curtain walls, terrazzo surfaces, stucco, tile grout, and decorative concrete. 

Geothermal cements are also employed to fix the steel wellbore casing in place and tie it to the surrounding rock (8). These are prepared as slurries of Portland cement (qv) in water and pumped into place. Additional components such as silica flour, perlite, and bentonite clay are often added to modify the flow properties and stability of the cement, and a retarder is usually added to the mixture to assure that the cement does not set up prematurely. Cements must bond well to both steel and rock, be noncorrosive, and water impermeable after setting. In hydrothermal applications, temperature stability is critical. Temperature cycling of wellbores as a result of an intermittent production schedule can cause rupture of the cement, leading to movement and, ultimately, failure of the wellbore casing. 

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