Ships, concrete

In the past 30 years, the ready-mixed concrete industry became the primary customer for cement manufacturers. In 1990 more than 72% of the cement shipped was sold to the ready-mixed concrete industry, compared with 63% in 1975. The other primary uses are in building materials, concrete products, and highway constmction. 

Concrete pressure vessels may be used in applications that require large sizes. Such vessels, if made of steel, would be too large and heavy to ship. Through the use of posttensioned (prestressed) concrete, the vessel is fabricated on the site. In this construc tion, the reinforcing steel is placed in tubes or plastic covers, which are cast into the concrete. Tension is applied to the steel after the concrete has acquired most of its strength. 

Considerable stray currents can, of course, be caused by dc-driven cranes that load and unload ships where the rails act as the return conductor for the current. The rails run parallel to the harbor basin, quay walls of steel-reinforced concrete or steel piling walls. These can take up a large part of the stray current and conduct it further because of their small longitudinal resistance. Noticeable stray current inter-... 

Ferric sulfate is usually stored in the dry state either in the shipping bags or in bulk in concrete or steel bins. Bulk storage bins should be as fight as possible to avoid moisture absorption, but dust collector vents are permissible and desirable. Hoppers on bulk storage bins should have a minimum slope of 36 however, a greater angle is preferred. 

Some mercury has also been inadvertently dumped at sea. In 2003, after years of searching, the Norwegian Navy found a German U-boat that had simk in 1945 dmdng World War II about 56 km from their coast in l40-m water depth. This ship was transporting 65 tonnes of mercury to Japan. About 4 kg has escaped and contaminated an area covering 30,000 m, with elevated concentrations found in the sediments and benthos. A debate is now underway as to whether to try to recover the mercury or to seal it in place with layers of concrete, sand, and gravel. 

There are two useful side products. The H2Sip6 is shipped as a 20-25 % aqueous solution for fluoridation of drinking water. Fluorosilicate salts find use in ceramics, pesticides, wood preservatives, and concrete hardeners. Uranium, which occurs in many phosphate rocks in the range of 0.005-0.03% of UsOg, can be extracted from the dilute phosphoric acid after the filtration step, but this is not a primary source of the radioactive substance. The extraction plants are expensive and can only be justified when uranium prices are high. 

Polymers are all around us. They serve as the very basis of both plant and animal life as proteins, nucleic acids, and polysaccharides. In construction they serve as the concrete, insulation, and wooden and composite beams. At home they are found as the materials for our rugs, pillows, curtains, coatings, wastepaper baskets, water pipes, window glass, and ice cube trays. In transportation they are present in ever-increasing amounts in our aircraft, automobiles, ships, and trucks. In communication they form critical components in our... 

The loss function, which is the concrete form of Taguchi s definition of quality The quality of a product is the loss caused by the product to society from the time the product is shipped . 

He has published and/or edited 27 books, including the Environmental Engineer s Handbook, and prepared the "Compromise Plan" for the Danube River, which was diverted by Slovakia into a concrete-lined bypass canal. The "Compromise Plan" resolves the conflict between the shipping and power generation considerations on the one hand and environmental concerns on the other. 

Common uses of the impressed current method of protection include long transmission pipelines, complex underground structures, marine structures, ship hulls, and replacement for dissipated galvanic systems, large condenser water boxes, reinforcing steel in concrete, bare or poorly coated structures, unisolated structures and water storage tank interiors. 

Part of the circulating solution is continuously withdrawn as a 20-25 percent aqueous solution of H2SiF6. The solution is shipped in rubber-lined tank cars and is used for fluoridation of drinking water, the preparation of fluosilicates, and production of A1F3. These salts find use in ceramics, pesticides, wood preservatives, concrete hardeners, and aluminum production. 

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