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Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement that hardens (cures) over time. In the past limebased cement binders were often used, such as lime putty, but sometimes with other hydraulic cements, such as a calcium aluminate cement or with Portland cement to form Portland cement concrete. Many other non-cementitious types of concrete exist with other methods of binding aggregate together, including asphalt concrete with a bitumen binder, which is frequently used for road surfaces, and polymer concretes that use polymers as a binder.
A cement is a binder, a substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (aggregate) together. Cement mixed with fine aggregate produces mortar for masonry, or with sand and gravel, produces concrete. Concrete is the most widely used material in existence and is only behind water as the planet's most-consumed resource.
Underground hard rock mining refers to various underground mining techniques used to excavate hard minerals, usually those containing metals such as ore containing gold, silver, iron, copper, zinc, nickel, tin and lead, but also involves using the same techniques for excavating ores of gems such as diamonds or rubies. Soft rock mining refers to excavation of softer minerals such as salt, coal, or oil sands.
The Magdalen Islands are a small archipelago in the Gulf of Saint Lawrence with a land area of 205.53 square kilometres (79.36 sq mi). Administratively, the islands are part of the Gaspésie–Îles-de-la-Madeleine region in the Canadian province of Quebec, but geographically, they are closer to the Maritime provinces than to the Gaspé Peninsula, on the Quebec mainland.
A road surface, or pavement, is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past, gravel road surfaces, cobblestone and granite setts were extensively used, but thet have mostly been replaced by asphalt or concrete laid on a compacted base course. Asphalt mixtures have been used in pavement construction since the beginning of the 20th century and are of two types: metalled roads and unmetalled roads. Metalled roadways are made to sustain vehicular load and so are usually made on frequently-used roads. Unmetalled roads, also known as gravel roads, are rough and can sustain less weight. Road surfaces are frequently marked to guide traffic.
Fly ash or flue ash, also known as pulverised fuel ash in the United Kingdom, is a coal combustion product that is composed of the particulates (fine particles of burned fuel) that are driven out of coal-fired boilers together with the flue gases. Ash that falls to the bottom of the boiler's combustion chamber (commonly called a firebox) is called bottom ash. In modern coal-fired power plants, fly ash is generally captured by electrostatic precipitators or other particle filtration equipment before the flue gases reach the chimneys. Together with bottom ash removed from the bottom of the boiler, it is known as coal ash. Depending upon the source and composition of the coal being burned, the components of fly ash vary considerably, but all fly ash includes substantial amounts of silicon dioxide (SiO2) (both amorphous and crystalline), aluminium oxide (Al2O3) and calcium oxide (CaO), the main mineral compounds in coal-bearing rock strata.
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in its natural form as a crystalline mineral is known as rock salt or halite. Salt is present in vast quantities in seawater, where it is the main mineral constituent. The open ocean has about 35 grams (1.2 oz) of solids per liter of sea water, a salinity of 3.5%.
Shotcrete, gunite, or sprayed concrete is concrete or mortar conveyed through a hose and pneumatically projected at high velocity onto a surface, as a construction technique, first used in 1914. It is typically reinforced by conventional steel rods, steel mesh, or fibers.
Sorel cement is a non-hydraulic cement first produced by the French chemist Stanislas Sorel in 1867.
The Panama Canal locks are a lock system that lifts ships up 85 feet to the main elevation of the Panama Canal and down again. The original canal had a total of six steps for a ship's passage. The total length of the lock structures, including the approach walls, is over 1.9 miles (3 km). The locks were one of the greatest engineering works ever to be undertaken when they opened in 1914. No other concrete construction of comparable size was undertaken until the Hoover Dam, in the 1930s.
The ancient Romans were famous for their advanced engineering accomplishments, although some of their inventions were improvements on older ideas, concepts and inventions. Technology for bringing running water into cities was developed in the east, but transformed by the Romans into a technology inconceivable in Greece. The architecture used in Rome was strongly influenced by Greek and Etruscan sources.
DUCRETE is a high density concrete alternative investigated for use in construction of casks for storage of radioactive waste. It is a composite material containing depleted uranium dioxide aggregate instead of conventional gravel, with a Portland cement binder.
A deep geological repository is a way of storing toxic or radioactive waste within a stable geologic environment. It entails a combination of waste form, waste package, engineered seals and geology that is suited to provide a high level of long-term isolation and containment without future maintenance. A number of mercury, cyanide and arsenic waste repositories are operating worldwide including Canada and Germany.
A tremie is a watertight pipe, usually of about 250mm inside diameter, with a conical hopper at its upper end above the water level. It may have a loose plug or a valve at the bottom end. A tremie is used to pour concrete underwater in a way that avoids washout of cement from the mix due to turbulent water contact with the concrete while it is flowing. This produces a more reliable strength of the product. Common applications include the following.
Stanislas Sorel was a French chemist, raised the son of a poor clock-maker.
Friedel's salt is an anion exchanger mineral belonging to the family of the layered double hydroxides (LDHs). It has affinity for anions as chloride and iodide and is capable of retaining them to a certain extent in its crystallographical structure.
The Asse II mine is a former salt mine used as a deep geological repository for radioactive waste in the Asse Mountains of Wolfenbüttel, Lower Saxony, Germany.
The repository for radioactive waste Morsleben is a deep geological repository for radioactive waste in the rock salt mine Bartensleben in Morsleben, district Börde in the federal state Saxony-Anhalt, Germany.
The pit Konrad is a former iron ore mine proposed as a deep geological repository for medium- and low level radioactive waste in the city Salzgitter in the Metropolitan region Hannover-Braunschweig-Göttingen-Wolfsburg in southeast Lower Saxony, Germany, located between Hildesheim and Braunschweig. It has two shafts: Konrad I and Konrad II.
Diamond grinding is a pavement preservation technique that corrects a variety of surface imperfections on both concrete and asphalt concrete pavements. Most often utilized on concrete pavement, diamond grinding is typically performed in conjunction with other concrete pavement preservation (CPP) techniques such as road slab stabilization, full- and partial-depth repair, dowel bar retrofit, cross stitching longitudinal cracks or joints and joint and crack resealing. Diamond grinding restores rideability by removing surface irregularities caused during construction or through repeated traffic loading over time. The immediate effect of diamond grinding is a significant improvement in the smoothness of a pavement. Another important effect of diamond grinding is the considerable increase in surface macrotexture and consequent improvement in skid resistance, noise reduction and safety.
References
- ↑ pumpversatz Archived 2011-07-18 at the Wayback Machine
- ↑ Thyssen
- ↑ Investigation of a Salt-concrete seal Archived 2006-09-30 at the Wayback Machine
- ↑ "Endlager für radioaktive Abfälle Morsleben (ERAM)". Archived from the original on 2009-02-26.