Why is it necessary to care for concrete?
Despite the fact that concrete walls and ceilings look monolithic, in fact, it only seems so. Let's remember what is included in the concrete solution. First of all, no, not even cement, but sand, which there should be about 8 parts, then rubble - another 10-11 parts, and cement - 3 parts. Of course, the compositions can vary depending on the granularity of the sand and the size of the fractions of the rubble, the proportions can be 3: 2: 1( gravel / sand / cement) or 4: 2: 1, that's not the point.
Obviously the main thing - concrete, or artificial stone, consists of particles of sand and rubble, interconnected by cement .And, therefore, there can not be any monolithic speech, there is a moisture permeability, and freezing to a certain depth( depends on the brand of cement).And where does care for concrete, you ask. And what is meant by it? No, of course, there is no need to wipe a concrete surface with a cloth every month or, what's good, wash it with cleaning agents.
Care is carried out at a time when the mortar is being prepared and immediately after it has solidified. For example, to prevent your future monolith from being afraid of water, add water-repellent additives to the solution in addition to the components listed above. Otherwise, cracks form in the concrete structure, which sooner or later lead to the destruction of the slab.
After hardening, the concrete is covered with a hydrophobic compound, by conventional manual application, if the surface is completely dry, or under pressure, if, in your opinion, the damp penetrates into the upper layers of the plate.
Why does concrete crack and how to deal with it?
The reasons why the concrete is cracked, even reinforced, is more than enough. For example, moisture that has the property of penetrating into the smallest pores, and expanding during frosts, increasing voids, then during warming, water will melt and decrease in volume, and the released space will take some more moisture. And so on until the cracks develop between the voids, because of which the stove will eventually break down.
This is especially noticeable in the example of hinged balconies, the edges of which after 10 years of operation of the house are a rather sad sight - the absence of corners as such, protruding fittings. Intensive evaporation of moisture from the thickness of the slab can also lead to its cracking, for example, during a rain at a sufficiently low temperature, moisture penetrates into the pores, and then the sun begins to shine, concrete heats up, and steam from the water literally breaks its way outward. Fighting the destructive effects of moisture can be done by treating concrete with hydrophobic compounds, as mentioned above.
However, even in the absence of moisture in the structure, cracks can also arise due to the expansion of the concrete itself during the temperature rise and narrowing it during cooling. Of course, cracking will occur only when the temperature drops sharply, when the outer layers narrows during frosts, and in the depths the temperature drops more slowly and a voltage difference appears in the structure. Alas, it is impossible to fight with temperature drops, the only way to protect concrete walls and ceilings is to use frost-resistant mixtures and do not forget to apply various heaters.
Concrete treatment - what substances to use
Do not think that it is so simple - to choose the necessary hydrophobic-plasticizing liquid to improve the water repellent properties of concrete. To begin with, you need to decide for yourself how high the level of moisture resistance of the slab or wall should be, after which you use one or the other component. In this case it should be taken into account that some substances are used in the form of additives, and others, only as impregnations of , that is, the processing of concrete by them is carried out in the form of external application. By the way, waterproofing can be provided and exterior decoration.
Most often used are hydrophobizing silicone fluids, or, briefly, GKZ, related to the second and third group of additives for the effect of action, which reduce water permeability by 2-4.9 times and 1.4-1.9 times, respectively. These liquids include ethylhydrosiloxane liquid( GKZh-94, the second group), sodium ethylsiliconate( GKZh-10, the third group) and sodium methylsiliconate( GKZh-11, the third group).
But the most effective is the addition of sodium aluminomethyl siliconate AMCP-3, which is the result of the reaction of metallic aluminum with sodium methylsiliconate, and increases the water repellent properties of concrete 5 times. There are other similar substances belonging to the same group. Than to process concrete, it is necessary to solve on a situation, with an eye on climatic factors of district and a mark of concrete, and also on that for what purpose the design is erected from it.