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Hydrodemolition
Hydrodemolition (also known as hydro demolition, hydroblasting, hydro blasting, hydromilling, waterblasting, and waterjetting) is a concrete removal technique which utilizes high-pressure water, often containing an abrasive material, to remove deteriorated and sound concrete as well as asphalt and grout. This process provides an excellent bonding surface for repair material and new coating applications. First developed in Europe in the 1980s, this technology has become widely accepted for concrete removal and surface preparation throughout Europe and North America. Hydrodemolition is not used as much for demolition as it is for surface restoration and protection projects. When concrete has deteriorated or the reinforcing steel has begun to corrode, it is necessary to remove any unsound concrete and reinforcing bars (rebar) in order to replace it with new concrete and maintain the integrity of the structure. This process has also been used to remove sound concrete that is not com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chernobyl New Safe Confinement
The New Safe Confinement (NSC or New Shelter, rarely Arka) is a structure put in place in 2016 to confine the remains of the number 4 reactor unit at the Chernobyl Nuclear Power Plant, in Ukraine, which was destroyed during the Chernobyl disaster in 1986. The structure also encloses the temporary Shelter Structure (sarcophagus) that was built around the reactor immediately after the disaster. The New Safe Confinement is designed to prevent the release of radioactive contaminants, protect the reactor from external influence, facilitate the disassembly and decommissioning of the reactor, and prevent water intrusion. The New Safe Confinement is a megaproject that is part of the Shelter Implementation Plan and supported by the Chernobyl Shelter Fund. It was designed with the primary goal of confining the radioactive remains of reactor 4 for the next 100 years. It also aims to allow for a partial demolition of the original sarcophagus, which was hastily constructed by Chernobyl li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dams
A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aquaculture, and navigability. Hydropower is often used in conjunction with dams to generate electricity. A dam can also be used to collect or store water which can be evenly distributed between locations. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees (also known as dikes) are used to manage or prevent water flow into specific land regions. The earliest known dam is the Jawa Dam in Jordan, dating to 3,000 BC. The word ''dam'' can be traced back to Middle English, and before that, from Middle Dutch, as seen in the names of many old cities, such as Amsterdam and Rotterdam. History Ancient dams Early dam building took place in Mesopotamia and the Middle East. Da ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airfield Rubber Removal
Airfield rubber removal, also known as runway rubber removal, is the use of high pressure water, abrasives, chemicals and other mechanical means to remove the rubber from tires that builds up on airport runways. In the United States, the Federal Aviation Administration (FAA) specifies friction levels for safe operation of planes and measures friction coefficients for the evaluation of appropriate friction levels. Individual airports incorporate rubber removal into their maintenance schedules based on the number of take offs and landings that each airport experiences. Source of airfield rubber build-up When a plane lands, the tires are not spinning. The time it takes for the tires to get up to speed is referred to as "spin up time" (Speidel, 2002). During this time the tires are effectively dragging on the runway as well as being put under pressure by the weight of the airplane. This can be seen in the slight puff of smoke that comes from a landing aircraft's tires as they first to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Runway
According to the International Civil Aviation Organization (ICAO), a runway is a "defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft". Runways may be a man-made surface (often asphalt concrete, asphalt, concrete, or a mixture of both) or a natural surface (sod, grass, soil, dirt, gravel, ice, sand or road salt, salt). Runways, as well as taxiways and Airport apron, ramps, are sometimes referred to as "tarmac", though very few runways are built using Tarmacadam, tarmac. Takeoff and landing areas defined on the surface of water for seaplanes are generally referred to as waterways. Runway lengths are now International Civil Aviation Organization#Use of the International System of Units, commonly given in meters worldwide, except in North America where feet are commonly used. History In 1916, in a World War I war effort context, the first concrete-paved runway was built in Clermont-Ferrand in France, allowing local company Michelin to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure Washing
Pressure washing or power washing is the use of high-pressure water spray to remove loose paint, mold, grime, dust, mud, and dirt from surfaces and objects such as buildings, vehicles and concrete surfaces. The volume of a mechanical pressure washer is expressed in gallons or liters per minute, often designed into the pump and not variable. The pressure, expressed in pounds per square inch, pascals, or bar Bar or BAR may refer to: Food and drink * Bar (establishment), selling alcoholic beverages * Candy bar * Chocolate bar Science and technology * Bar (river morphology), a deposit of sediment * Bar (tropical cyclone), a layer of cloud * Bar (un ..., is designed into the pump but can be varied by adjusting the unloader valve. Machines that produce pressures from 750 to 30,000 psi (5 to 200 MPa) or more are available. The terms pressure washing and power washing are used interchangeably in many scenarios, and there is some debate as to whether they are actually differen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bulletproof Vest
A bulletproof vest, also known as a ballistic vest or a bullet-resistant vest, is an item of body armor that helps absorb the impact and reduce or stop penetration to the torso from firearm-fired projectiles and fragmentation from explosions. The vest may come in a soft form, as worn by many police officers, prison guards, security guards, and some private citizens, used to protect against stabbing attacks or light projectiles, using metallic or para-aramid components. Soldiers, police tactical units, marines, and special operations forces wear hard armors, either in conjunction with soft armor or alone, to protect against rifle ammunition or fragmentation. History Early modern era In 1538, Francesco Maria della Rovere commissioned Filippo Negroli to create a bulletproof vest. In 1561, Maximilian II, Holy Roman Emperor is recorded as testing his armor against gun-fire. Similarly, in 1590 Sir Henry Lee expected his Greenwich armor to be "pistol proof". Its actual effectivene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hard Hat
A hard hat is a type of helmet predominantly used in workplace environments such as industrial or construction sites to protect the head from injury due to falling objects, impact with other objects, debris, rain, and electric shock. Suspension bands inside the helmet spread the helmet's weight and the force of any impact over the top of the head. A suspension also provides space of approximately 30 mm (1.2 inches) between the helmet's shell and the wearer's head, so that if an object strikes the shell, the impact is less likely to be transmitted directly to the skull. Some helmet shells have a mid-line reinforcement ridge to improve impact resistance. The rock climbing helmet fulfills a very similar role in a different context and has a very similar design. A bump cap is a lightweight hard hat using a simplified suspension or padding and a chin strap. Bump caps are used where there is a possibility of scraping or bumping one's head on equipment or structure projections ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retaining Wall
Retaining walls are relatively rigid walls used for supporting soil laterally so that it can be retained at different levels on the two sides. Retaining walls are structures designed to restrain soil to a slope that it would not naturally keep to (typically a steep, near-vertical or vertical slope). They are used to bound soils between two different elevations often in areas of terrain possessing undesirable slopes or in areas where the landscape needs to be shaped severely and engineered for more specific purposes like hillside farming or roadway overpasses. A retaining wall that retains soil on the backside and water on the frontside is called a seawall or a bulkhead. Definition A wall for holding in place a mass of earth or the like, as at the edge of a terrace or excavation. A retaining wall is a structure designed and constructed to resist the lateral pressure of soil, when there is a desired change in ground elevation that exceeds the angle of repose of the soil. A basemen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stadiums
A stadium ( : stadiums or stadia) is a place or venue for (mostly) outdoor sports, concerts, or other events and consists of a field or stage either partly or completely surrounded by a tiered structure designed to allow spectators to stand or sit and view the event. Pausanias noted that for about half a century the only event at the ancient Greek Olympic festival was the race that comprised one length of the stadion at Olympia, where the word "stadium" originated. Most of the stadiums with a capacity of at least 10,000 are used for association football. Other popular stadium sports include gridiron football, baseball, cricket, the various codes of rugby, field lacrosse, bandy, and bullfighting. Many large sports venues are also used for concerts. Etymology "Stadium" is the Latin form of the Greek word " stadion" (''στάδιον''), a measure of length equalling the length of 600 human feet. As feet are of variable length the exact length of a stadion depends on the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Power Plant
A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a generator that produces electricity. , the International Atomic Energy Agency reported there were 422 nuclear power reactors in operation in 32 countries around the world, and 57 nuclear power reactors under construction. Nuclear plants are very often used for base load since their operations, maintenance, and fuel costs are at the lower end of the spectrum of costs. However, building a nuclear power plant often spans five to ten years, which can accrue to significant financial costs, depending on how the initial investments are financed. Nuclear power plants have a carbon footprint comparable to that of renewable energy such as solar farms and wind farms, and much lower than fossil fuels such as natural gas and brown coal. Despite some spectacula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
