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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&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&nbs ... [...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 commonl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroculture
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 commonly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotary Kiln
A rotary kiln is a pyroprocessing device used to raise materials to a high temperature (calcination) in a continuous process. Materials produced using rotary kilns include: * Cement * Lime * Refractories * Metakaolin * Titanium dioxide * Alumina * Vermiculite * Iron ore pellets They are also used for roasting a wide variety of sulfide ores prior to metal extraction. Principle of operation The kiln is a cylindrical vessel, inclined slightly from the horizontal, which is rotated slowly about its longitudinal axis. The process feedstock is fed into the upper end of the cylinder. As the kiln rotates, material gradually moves down toward the lower end, and may undergo a certain amount of stirring and mixing. Hot gases pass along the kiln, sometimes in the same direction as the process material (co-current), but usually in the opposite direction (counter-current). The hot gases may be generated in an external furnace, or may be generated by a flame inside the kiln. Such a flam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravity
In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the strong interaction, 1036 times weaker than the electromagnetic force and 1029 times weaker than the weak interaction. As a result, it has no significant influence at the level of subatomic particles. However, gravity is the most significant interaction between objects at the macroscopic scale, and it determines the motion of planets, stars, galaxies, and even light. On Earth, gravity gives weight to physical objects, and the Moon's gravity is responsible for sublunar tides in the oceans (the corresponding antipodal tide is caused by the inertia of the Earth and Moon orbiting one another). Gravity also has many important biological functions, helping to guide the growth of plants through the process of gravitropism and influencing the circ ... [...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 whol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Construction Aggregate
Construction aggregate, or simply aggregate, is a broad category of coarse- to medium-grained particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates are the most mined materials in the world. Aggregates are a component of composite materials such as concrete and asphalt; the aggregate serves as reinforcement to add strength to the overall composite material. Due to the relatively high hydraulic conductivity value as compared to most soils, aggregates are widely used in drainage applications such as foundation and French drains, septic drain fields, retaining wall drains, and roadside edge drains. Aggregates are also used as base material under foundations, roads, and railroads. In other words, aggregates are used as a stable foundation or road/rail base with predictable, uniform properties (e.g. to help prevent differential settling under the road or building), or as a low-cost exten ... [...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 O ... [...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 i ... [...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 ma ... [...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 als ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
