To itself the person From time immemorial builds habitation. Of what only materials were tried by it! The cave, a dugout, a hut from what is necessary - all suited at the beginning. The tree, a natural stone further was put to use. And, at last, have learnt to do a stone artificial on the basis of knitting substances. When it has occurred? Anybody with accuracy will not tell today. Only it is for certain known that such secret ancient Romans owned still. On slopes of Vesuvius they took volcanic sand. Humidified it is and in some weeks this weight turned in skaloobraznuju breed. Sand from Vesuvius went usually on a construction of harbours - Romans knew that sea water not only does not wash away their man-made rock, but does it even more strongly.
Sand from Vesuvius (and then began to find similar to it and in other places) named betumom. To save this the first in the history knitting, in betum began to add slices of a usual stone, and named these additives tsementumom.
There were years. Also the way of manufacturing of an artificial stone has been almost lost. Tell that here and there people found the rests of any not clear constructions. One of them, for example, have found out near Cologne. Wished to use this old stone for new constructions, but a stone in known then representation simply have not found. How many investigated walls, could not find out seams in any way, a laying. Have decided that this creation not human hands and were receded from ruins.
But the Roman experience has not disappeared completely. In the antique literature there were records about wonderful sand from Vesuvius, councils as it to use. There were also readers of ancient books. On the sly "сх=ѕь" and "чхьхэ=ѕё" again began to come back to people.
It is necessary to tell only that these names underwent in due course various semantic changes. At first "сх=ѕьюь" began to name and others knitting. The trace of it remained, for example, in the name "сш=ѕь" widely used nowadays at asphalting of streets.
Then "сх=ѕьюь" "сх=юэюь" already called a mix knitting with droblenym a stone. And itself droblenyj the stone has lost the initial name. "Нхьхэ=ѕьюь" "чхьхэ=юь" suddenly began to name for some reason all knitting. Our times have reached and remained in semantic value habitual to us concrete - a water mix knitting with a filler and cement - knitting.
But cement in our understanding - not knitting in general, and its quite certain kind. We know except it and much others. For example, usual clay - it is visible, this the first knitting, used by the person in a life. With clay it was simple to address: has shut water, has put a solution where follows-at a laying of furnaces, obmazke at home, etc. - also wait, while will dry up.
The Big efforts demands izvest. There is no saying, who the first has developed technology of its reception. In the literature met that it was applied still by ancient Greeks, but later, than there were their world famous palaces and temples, such as Parthenon in Athenes. Blocks of this building are not fastened by any solution, and keep strongly only because with surprising accuracy are adjusted to each other.
At us in the country the first plaster has appeared in the Kiev Russia, ancient Novgorod, Georgia - these constructions concern to XI-XII to centuries. At first plastered only temples, then public buildings and, at last, steels so to finish and apartment houses.
Initial raw materials for reception to exhaust as knitting the natural stone - limestone serves. It burn and receive so-called izvest-kipelku. Builders well are familiar with it. It in the form of white lumps bring on platforms then to shut water and to receive the limy dough or milk - initial raw materials for limy solutions.
One more widespread knitting - plaster. Receive plaster too from a natural stone is a so-called two-water plaster. It crush, heat up, sift. The different temperature of heating, grinding degree give the chance to receive a miscellaneous knitting.
If heat up plaster to 150...200°Р and sift through a sieve with 400 apertures on 1 sm 2 , receive semiwater plaster, or alabaster. A solution from alabaster most bystroshvatyvajushchijsja - to start it tverdenija enough five - seven minutes. But the received product is fragile.
To receive forming plaster (of which, in particular, do sheets of dry plaster), the high milling is necessary more. Here use a sieve in which on 1 sm 2 900 apertures are necessary.
Semiwater plaster widely apply in building practice. But except it there are also other plasters - all business in temperature of roasting of a natural stone.
Roasting at 200...300°Р gives plaster with smaller term tverdenija, than at alabaster, but at hardening the weight possesses lower durability.
Roasting at 500...750°Р gives waterless plaster which in general can not seize.
At 750...800°Р hydraulic plaster (estrih-plaster) starts to be formed and if to lift temperature for 200°Р we will receive normal hydraulic plaster (it still name architectural or medical). It very slowly seizes, but gives dense and strong weight.