History of application of lime.
The first evidence of the use of lime as a building material dates back to 4000 BC Egyptians, who used lime, gypsum in the building of the pyramids. Data from eastern
Quicklime obtained by calcination (burning) limestone or chalk at 1000-1200 ° C. The process of "burning" exercise in vertical shaft kilns lined inside refractory bricks. Blend, namely a mixture of limestone and coke load in the furnace through the top hole. Pieces of limestone and coke made such that their diameter was about 10 sm. Then air and topochni gases easily pass through the charge, and limestone decomposes uniformly throughout the mass. Hot gases arising from combustion and decomposition of limestone, rising up, slowly cooled to warm the batch. Scorched lime falls to the bottom of the furnace, where cool by air, which supplied from below.
Lime is widely used in the construction industry, as well as in the chemical industry to get bleaching powder. Annual universal production of lime is hundreds of millions of tons. In the construction slaked lime is used. For this purpose quicklime treated water. At that porous lumps of quicklime greedily absorb water and react with it, emitting a large amount of heat. As a result water evaporated, and quicklime turns into thick paste of slaked lime. In case of excess of water slaked lime produced in a doughy mass. In the construction slaked lime mix of 3-4 parts of sand and add that amount of water that formed pappy mass. This mass is called mortar and used for binding bricks in building brick walls as a plaster. To the mortar, which is used for binding bricks and external plaster sometimes add cement and to the inside plaster – gypsum. Binding properties of slaked lime are based on the fact that slaked lime gradually crystallizes and reacting with carbon dioxide of air change into a solid mass.
ecological significance of lime was found in the recent past when the public
realized the need of environmental protection. We can say that lime is the
material that comes from nature; it is very useful for conservation and return
to nature. Nowadays, more than 20% of lime is used for environmental
Lime is produced from raw materials, which are almost everywhere on our planet (huge reserves of limestone), or raw materials imported for the minimum distance.
Production costs are not expensive - fuel for burning and waste, mainly CO2. Features lime: cleaning properties - the neutralization of acid environment, the creation of insoluble compounds with most chemicals, the stabilization of the sediment by absorption water from different layers,
distraction of bacteria, it is suitable for water purification, to reduce the hardness of water.
Lime – is a powerful building material, so a great future.
History of cement.
At all times people
looked for a material that could stick stones, to strengthen the wall. For this
purpose people used clay, the solution of limestone and gypsum. As time goes
by, the Romans invented the mixture, which gave the opportunity to build strong
and durable construction. Extraction technologies were known in ancient
In the early 19
century the British decorator D. Aspdin on your own
kitchen heated a mixture of well-crushed limestone and clay in the kitchen
stove, then powdered it and got hydraulic cement that became solid by adding
water. Aspdin named this product - portland cement, because during
cement production, he used stones from the quarry, located on the
production mainly used fusible clay, agrility, and clay shale, which forms part of
the cement batch. The second main component of it is carbonate rock. The raw
material for cement production are limestone and clay which are mixed in
certain proportion (75-80% limestone and 20 - 25% clay) and roasted about 1450
° C. Roast carried out in special cylindrical furnaces, refractory material
contained within. Modern cement kiln reaches
Cement is usually used in mixtures with sand. In one part of cement weight use 3-5 parts of sand. From this mixture with water produced semisolid dough mass, which is called cement. After a time grout become hard and looks like a stone. Under normal temperature this process continued for almost a month. This phenomenon occurs owing to a complex chemical reaction. Mixing cement with gravel and detritus makes concrete. If concrete filled iron skeleton (iron rod, wire, etc.), then it is called reinforced concrete. Cement (concrete) is very tightly connected with iron and it has the similar coefficient of thermal expansion, at the same time concrete has a high resistance to compression, and metal structures - to bending. Concrete and reinforced concrete have very high hardness and mechanical strength; they are widely used in the construction of hydroelectric power stations, bridges, canals, factory buildings and house building.
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