the Hygienic characteristic of building materials
The Big variety of the building materials applied in building of inhabited and public buildings, unites the basic indicators of their quality. From the hygienic point of view those indicators which characterise maintenance of a thermal mode in a building first of all are important: heat conductivity, a thermal capacity, air permeability etc. As heat conductivity understand ability of a material to pass heat. It occurs owing to a difference of temperatures outside and in a building. Heat conductivity is in inversely proportional dependence on porosity of a building material: the more in it of emptiness, the heat conductivity there is less. Therefore melkoporistye materials less teploprovodny, than krupnoporistye. At increase of humidity of air (in the winter, in rainy weather) air in a material time is replaced with a moisture and heat conductivity of such material increases, as water the best conductor of heat, than air. Therefore it is very important to protect materials and designs from humidifying.
As a thermal capacity understand ability of a material to absorb and keep heat. The bolshej a thermal capacity the material of walls possesses, the more slowly they are warmed, but thus and more slowly lose heat. Heat conductivity and a thermal capacity are in inversely proportional dependence. The above heat conductivity, the more low a material thermal capacity, and on the contrary.
Air permeability of building materials is insignificant and has no essential value for a microclimate of premises. A number of indicators (water absorption, moisture-yielding ability, humidity, water penetration, hygroscopicity) characterise the relation of a building material.k to water. Hygroscopicity - property of materials sorbirovat a moisture from air surrounding them. The concept sorbtsija includes two phenomena of absorption by moisture materials (in the form of steam): adsorption - absorption of steam by surfaces of a material and its time and absorption - steam absorption by its dissolution in a firm body.
For normal conditions of a life in buildings such indicators, as durability and durability of a material matter also.
Hence, the materials applied in building of inhabited and public buildings, should possess the bad heat conductivity, necessary durability, fire resistance and not to allocate in air of toxic substances.
Kinds of building materials. Now to building of inhabited and public buildings are applied natural (a tree, clay, natural stones), artificial (the burnt and silicate brick, concrete) and polymeric materials (polistirolnye tiles, linoleum).
Wood materials possess bad heat conductivity, are durable, easily give in to processing, but are subject to rotting, easy inflammability. To avoid ignition of wood designs it is possible, supporting vozdushnosuhoe a tree condition. However under the influence of non-uniform shrinkage probably rastreskivanie a tree, at namokanii - its swelling. Hence, it is necessary to support humidity of a tree that is not always possible in known limits. Besides, danger of destruction of a tree is connected with humidity by house mushrooms. Their dry disputes are carried by air and, getting on a tree, develop under a condition, if its humidity above 20%. House mushrooms concern present house (Merulius lacry-mans), white house (Poria vaporaria) and a filmy mushroom (Coniophora cerebella). Under the influence of these mushrooms the tree breaks up on prizmaticheskie particles, loses weight, is easily pounded in a powder and completely loses the constructive durability. Threat of falling of interfloor overlappings, floors and roofing beams is created, the building comes to an emergency condition. Maintenance of an air-dry condition of designs from a tree - the basic way of the prevention of their rotting. An auxiliary measure is propityvanie a tree antiseptics (sodium fluoride, kreozotovym oil, karbolineumom, etc.), interfering development of mushrooms.
All above-stated limits use of a tree as a building material. Coniferous breeds - a pine, a fur-tree and a larch are considered as the most valuable. Their advantages are straightness of a trunk, ease of processing, a wide circulation in territory of the USSR. Clay is used for building of one-storeyed buildings in separate national republics (Ukraine).
Good natural building materials are natural calcareous porous materials - the shell rocks formed on a place of the former seas from the rests of armours of water organisms, fastened by carbonic salts of calcium; tufy, representing deposits of the earth which have fallen asleep on a surface of a volcanic lava; sandstones.
From artificial building materials the greatest distribution was received by the red burnt brick, the basic which compound component is clay. For reduction of volume weight of a brick to clay began to add sawdust which at roasting burnt out in summary the superficial brick having sufficient durability and same teploizoljatsionnye of property turned out, as the red burnt brick. The brick is applied to building also perforated, or hollow. A little bit less often in building of residential buildings the silicate brick is applied. It from sand (92-95%) is produced and to exhaust (5-8%); has light grey colour. Speed of manufacturing and cheapness of a silicate brick provide to it wide application.
Concrete represents an artificial mix in the form of a stone, consisting of rubble, gravel, sand, cement and water. For decrease in volume weight at manufacturing of easy concrete use fuel both industrial slags and other materials. At introduction in thickness of concrete of steel armature receive ferro-concrete. Last is applied to any designs - walls, overlappings, beams, the bases. In modern building - blocks and panels modular concrete designs are applied to walls of buildings.
Polymeric building materials are applied often at furnish of buildings as high decorative qualities are inherent in them. Many of them have small volume weight, low heat conductivity, good soundproofing ability. Besides, distinctive features of some of them are a transparency, the big ability to pass ultra-violet radiation, chemical and protivokorrozijnaja stability, inability to rotting. Unlike traditional building materials they have a difficult chemical compound and possess potential ability adversely to influence a human body while in service. Therefore in housing construction those polymeric materials which are chemically stable are applied only and do not allocate in environment of flying substances in the quantity which is hazardous to health of the person. Substances with that end in view allocated from polymeric materials investigate on animals. Data of toxicological experiment compare with admissible level (DU) migrations and maximum permissible quantity (maximum concentration limit) of these substances in atmospheric air and solve a question on application of polymeric materials in building of inhabited and public buildings.
Building designs. Residential buildings build a little - (2-3 floors) and many-storeyed. Distinguish following kinds of floors: elevated - floors are located above sidewalk; socle - floors are located below sidewalk no more than on half of height of a premise; basement floors are located below sidewalk more than on half of height of a premise; the mansard buildings located on an attic. Premises in socle and basement floors are not authorised to be placed, about what it is underlined in SNiP П-Л.1-71. Basic elements of buildings are the base, walls, overlappings, a roof, partitions, ladders, balconies, windows, doors.
The Base is zaglublennaja in soil a part of the building executed from a brick or ferro-concrete and taking up weight of overlying designs. The bases happen tape buildings settling down on perimetre, or faltering, under construction on the strong bases. Besides, the bases happen continuous. The base should be zaglublen not less than on 0,5 m from a surface of the earth or a cellar floor. As continuation of the base above a surface of the earth and to a ground floor floor the socle representing utolshchennuju a part of a wall in height not less 0,7 m from level of the earth serves.
Zaglublennyj in soil the base is in the damp environment, and capillary penetration of a moisture can lead otsyrevaniju walls first of all within the ground floor. That it has not occurred, the base sole should lay not less than on 0,5 m above subsoil waters, and between a socle and a wall the waterproofing course (2 layers of roofing material) is laid.
External walls do as from natural, and artificial materials. Walls should possess small heat conductivity and high teploustojchivostju, low zvukoprovodnostju and sound transmission to be strong enough and steady. Internal walls build of easy concrete, gipsobetona, a brick, various tiled materials and a tree. These walls should not have ledges, roughnesses and cracks to warn accumulation of a settling dust and nesting of parasites-insects. Colouring of walls and their furnish has the big hygienic value. Optimum for colouring are yellowish or greenish tone. Walls in kitchen and a bathroom need to be spread to half of height tiles or to cover with an oil paint.
Overlappings over underground space of the ground floor, interfloor and over the top floor can be large-panel the area in one room or as a flooring from ready separate elements from concrete in the form of trays or two-hollow plates. At maloetazhnom building (not above three floors) apply wooden overlappings.
Windows should be the sufficient size, in regular intervals distribute light, have such design of covers, to give access to external air for airing. Doors should be well driven, that isolation of premises was not broken. In floors there should not be cracks and cracks where the dirt and a dust can accumulate. The roof should protect a building from an atmospheric precipitation.
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