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Expanded Clay Aggregate
Lightweight expanded clay aggregate (LECA) or expanded clay (exclay) is a lightweight aggregate made by heating clay to around in a rotary kiln. The yielding gases expand the clay by thousands of small bubbles forming during heating producing a honeycomb structure. LECA has an approximately round or potato shape due to circular movement in the kiln and is available in different sizes and densities. LECA is used to make lightweight concrete products and other uses. History LECA was developed about 1917 in Kansas City, Missouri, to the production in a rotary kiln of a patented expanded aggregate known as Haydite which was used in the construction of SS Selma, an ocean-going ship launched in 1919. Following in the USA was the development of a series of aggregates known as Gravelite, Perlite, Rocklite, etc. In Europe, LECA commenced in Denmark, Germany, Netherlands, and UK. Characteristics LECA is usually produced in different sizes and densities from up to , commonly 0–4&nbs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroton
Lightweight expanded clay aggregate (LECA) or expanded clay (exclay) is a lightweight aggregate made by heating clay to around in a rotary kiln. The yielding gases expand the clay by thousands of small bubbles forming during heating producing a honeycomb structure. LECA has an approximately round or potato shape due to circular movement in the kiln and is available in different sizes and densities. LECA is used to make lightweight concrete products and other uses. History LECA was developed about 1917 in Kansas City, Missouri, to the production in a rotary kiln of a patented expanded aggregate known as Haydite which was used in the construction of SS Selma, an ocean-going ship launched in 1919. Following in the USA was the development of a series of aggregates known as Gravelite, Perlite, Rocklite, etc. In Europe, LECA commenced in Denmark, Germany, Netherlands, and UK. Characteristics LECA is usually produced in different sizes and densities from up to , commonly 0–4& ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and even by industry. Further, both spellings are often used ''within'' a particular industry or country. Industries in British English-speaking countries typically use the "gauge" spelling. is the pressure relative to the ambient pressure. Various #Units, units are used to express pressure. Some of these derive from a unit of force divided by a unit of area; the International System of Units, SI unit of pressure, the Pascal (unit), pascal (Pa), for example, is one newton (unit), newton per square metre (N/m2); similarly, the Pound (force), pound-force per square inch (Pounds per square inch, psi) is the traditional unit of pressure in the imperial units, imperial and United States customary units, U.S. customary systems. Pressure may also be e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquaponics
Aquaponics is a food production system that couples aquaculture (raising aquatic animals such as fish, crayfish, snails or prawns in tanks) with hydroponics (cultivating plants in water) whereby the nutrient-rich aquaculture water is fed to hydroponically grown plants. As existing hydroponic and aquaculture farming techniques form the basis of all aquaponic systems, the size, complexity, and types of foods grown in an aquaponic system can vary as much as any system found in either distinct farming discipline. History Aquaponics has ancient roots, although there is some debate on its first occurrence: *Aztec cultivated agricultural islands known as ''chinampas'' in a system considered by some to be an early form of aquaponics for agricultural use, where plants were raised on stationary (or sometime movable) islands in lake shallows and waste materials dredged from the Chinampa canals and surrounding cities were used to manually irrigate the plants. *South China and the whole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroponics
Hydroponics is a type of horticulture and a subset of hydroculture which involves growing plants, usually crops or medicinal plants, without soil, by using water-based mineral nutrient solutions in aqueous solvents. Terrestrial or aquatic plants may grow with their roots exposed to the nutritious liquid or in addition, the roots may be mechanically supported by an inert medium such as perlite, gravel, or other substrates. Despite inert media, roots can cause changes of the rhizosphere pH and root exudates can affect rhizosphere biology and physiological balance of the nutrient solution by secondary metabolites. Transgenic plants grown hydroponically allow the release of pharmaceutical proteins as part of the root exudate into the hydroponic medium. The nutrients used in hydroponic systems can come from many different organic or inorganic sources, including fish excrement, duck manure, purchased chemical fertilizers, or artificial nutrient solutions. Plants are com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autoclaved Aerated Concrete
Autoclaved aerated concrete (AAC) is a lightweight, precast, foam concrete building material suitable for producing concrete masonry unit like blocks. Composed of quartz sand (SiO2 with impurities), calcined calcium sulfate (CaSO4, a.k.a. plaster of paris), lime (CaO), cement, water and aluminum powder, AAC products are cured under heat and pressure in an autoclave. Invented in the mid-1920s, AAC simultaneously provides structure, insulation, and fire- and mold-resistance. Forms include blocks, wall panels, floor and roof panels, cladding (façade) panels and lintels. AAC products may be used for both interior and exterior construction, and may be painted or coated with a stucco or plaster compound to guard against the elements, or covered with siding materials such as veneer brick or vinyl siding. In addition to their quick and easy installation, AAC materials can be routed, sanded, or cut to size on site using standard power tools with carbon steel cutters. Etymology ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concrete Slab
A concrete slab is a common structural element of modern buildings, consisting of a flat, horizontal surface made of cast concrete. Steel- reinforced slabs, typically between 100 and 500 mm thick, are most often used to construct floors and ceilings, while thinner ''mud slabs'' may be used for exterior paving . In many domestic and industrial buildings, a thick concrete slab supported on foundations or directly on the subsoil, is used to construct the ground floor. These slabs are generally classified as ''ground-bearing'' or ''suspended''. A slab is ground-bearing if it rests directly on the foundation, otherwise the slab is suspended. For multi-story buildings, there are several common slab designs : * Beam and block, also referred to as ''rib and block'', is mostly used in residential and industrial applications. This slab type is made up of pre-stressed beams and hollow blocks and are temporarily propped until set, typically after 21 days. * A hollow core slab which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concrete Masonry Unit
A concrete masonry unit (CMU) is a standard-size rectangular block used in building construction. CMUs are some of the most versatile building products available because of the wide variety of appearances that can be achieved using them. Those that use cinders (fly ash or bottom ash) as an aggregate material are called cinder blocks in the United States, breeze blocks (''breeze'' is a synonym of ''ash'') in the United Kingdom, and hollow blocks in the Philippines. In New Zealand and Canada they are known as concrete blocks (a name common in the United States also). In New Zealand, they are also called construction blocks. In Australia, they are known as Besser blocks or Besser bricks, because the Besser Company was a major supplier of machines that made concrete blocks. Clinker blocks use clinker as aggregate. In non-technical usage, the terms ''cinder block'' and ''breeze block'' are often generalized to cover all of these varieties. Composition Concrete blocks are made ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Filtration
Filtration is a physical separation process that separates solid matter and fluid from a mixture using a ''filter medium'' that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filter medium are described as ''oversize'' and the fluid that passes through is called the ''filtrate''. Oversize particles may form a filter cake on top of the filter and may also block the filter lattice, preventing the fluid phase from crossing the filter, known as ''blinding''. The size of the largest particles that can successfully pass through a filter is called the effective ''pore size'' of that filter. The separation of solid and fluid is imperfect; solids will be contaminated with some fluid and filtrate will contain fine particles (depending on the pore size, filter thickness and biological activity). Filtration occurs both in nature and in engineered systems; there are biological, geological, and industrial forms. Filtration is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drainage
Drainage is the natural or artificial removal of a surface's water and sub-surface water from an area with excess of water. The internal drainage of most agricultural soils is good enough to prevent severe waterlogging (anaerobic conditions that harm root growth), but many soils need artificial drainage to improve production or to manage water supplies. History Early history The Indus Valley civilization had sewerage and drainage systems. All houses in the major cities of Harappa and Mohenjo-daro had access to water and drainage facilities. Waste water was directed to covered gravity sewers, which lined the major streets. 18th and 19th century The invention of hollow-pipe drainage is credited to Sir Hugh Dalrymple, who died in 1753. Current practices Geotextiles New storm water drainage systems incorporate geotextile filters that retain and prevent fine grains of soil from passing into and clogging the drain. Geotextiles are synthetic textile fabrics specially m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substrate (biology)
In biology, a substrate is the surface on which an organism (such as a plant, fungus, or animal) lives. A substrate can include biotic or abiotic materials and animals. For example, encrusting algae that lives on a rock (its substrate) can be itself a substrate for an animal that lives on top of the algae. Inert substrates are used as growing support materials in the hydroponic cultivation of plants. In biology substrates are often activated by the nanoscopic process of substrate presentation. In agriculture and horticulture * Cellulose substrate * Expanded clay aggregate (LECA) * Rock wool * Potting soil * Soil In animal biotechnology Requirements for animal cell and tissue culture Requirements for animal cell and tissue culture are the same as described for plant cell, tissue and organ culture (In Vitro Culture Techniques: The Biotechnological Principles). Desirable requirements are (i) air conditioning of a room, (ii) hot room with temperature recorder, (iii) microsc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from those that are so weak that they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time period. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume. The word ''tremor'' is also used for non-earthquake seismic rumbling. At the Earth's surface, earthquakes manifest themselves by shaking and displacing or disrupting the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melting
Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which increases the substance's temperature to the melting point. At the melting point, the ordering of ions or molecules in the solid breaks down to a less ordered state, and the solid "melts" to become a liquid. Substances in the molten state generally have reduced viscosity as the temperature increases. An exception to this principle is the element sulfur, whose viscosity increases in the range of 160 °C to 180 °C due to polymerization. Some organic compounds melt through mesophases, states of partial order between solid and liquid. First order phase transition From a thermodynamics point of view, at the melting point the change in Gibbs free energy ''∆G'' of the substances is zero, but there are non-zero changes in the entha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
