In building use a different kind materials and the products created by a pas to a basis of the knitting. These are concrete and solutions, bituminoznye materials, and also artificial stone products of factory manufacturing (shaped details of buildings, stenovye and ceiling panels, a various kind of a tile, etc.).
As we talk about plaster we will consider only building solutions concerning it.
These solutions on structure and properties are similar to concrete mixes. A difference that at concrete along with sand necessarily there are large fillers - gravel, rubble. Into building solutions enter only small fillers. After all appointment of these solutions much more thin, than concrete: filling of seams, connection of piece materials in a laying, a covering of surfaces a thin protective or decorative layer.
Building solutions differ:
) by the form knitting (cement, limy, difficult, mixed);
) on properties knitting (air and hydraulic);
) by the nature of fillers: heavy (with ordinary sand) and lungs (with sand pumiceous, slag, etc.).
Use also special solutions, for example waterproofing, sound-proof, decorative.
In All solutions are inherent eight properties characterising them.
1. Density - weight of a solution in natural state in certain volume (for example, weight of 1 m 3 ).
2. Durability - ability to resist to various mechanical influences - to blows, breaks. It can be characterised strength at compression of samples - cubes in the size 70.7Х70,7Х70,7 mm at the age of 28 days. Depending on at what pressure the cube collapses, define durability mark. Are established for building solutions of mark 200, 150, 100, 50, 25, 10, 4, 2.
3. Porosity - degree of density of weight of a solution, degree of presence of emptiness in the given volume. The ego a condition as we will see further, influences variety of the subsequent properties.
4. Heat conductivity - ability to pass heat. Porosity plays here large role. It is known that air - a bad conductor of heat. L it fills closed pores. Hence, the more in a solution of such time, the less its heat conductivity
5 both 6. Water absorption and water penetration. Here again on the foreground porosity, character of a time act. Closed pores do not absorb water, do not pass it through a solution layer. If a time in napolniteljah opened, they can transform our artificial stone into the present stone sponge.
7. Frost resistance - ability to resist to destroying influence of low temperatures. The solution should type certain durability before it will freeze. Not had time to seize, it at thawing will lose durability.
8. Plasticity, udoboukladyvaemost - ability of a solution to keep the form given to it not to be stratified, at hardening not to burst, not to be showered. Plasticity is defined mainly by property knitting and grain structure of a filler.
Plasticity should not be mixed with the consistence of a solution depending on a quantity of water in a solution.
There are quite certain norms of density, mobility of a solution. In the conditions of building it is necessary to check, whether the weight available for you (brought with central rastvornogo knot or prepared on a place) answers the established norms.
a Fig. 1. A cone of StrojTsNiL
For this purpose there is a simple adaptation - a cone of StrojTsNiL with a corner in top 30° and weight of 300 (fig. 1). On a cone body there are divisions. Immersing a cone in the prepared solution, working looks, on what depth it has fallen. The solutions having various appointment (for obryzga, the first or second layer of earth, nakryvochnogo a layer), differ also different depth of immersing.
Durability of a solution depends first of all on the knitting. The strongest - cement mortals. And the above cement mark, the more strongly a solution.
But in construction engineering building by manufacture of plaster works cement and the more so vysokomarochnye cement mortals are applied rather seldom. The matter is that cement of roads. And more simple, cheaper knitting give the solutions quite providing the requirements, shown to the majority of objects of construction engineering building.
Cement mortals are necessary at furnish of external walls and premises with the raised humidity. Premises with normal humidity plaster, applying the so-called difficult or mixed solutions. Difficult solutions contain cement and any another knitting (for example, cement-limy solutions). The mixed solutions shut several knitting, but without cement (for example, an izvestkovo-plaster solution).
It is not necessary to think that the solution will be stronger if to place in it a lot of the knitting. In all the austerity measure is necessary. So-called fat solutions - with a considerable quantity knitting - at tverdenii give big usadku that is no means always admissible. And lean solutions - with the small maintenance knitting - differ small usadkoj.