Heavy concrete is used in the installation of walls and ceilings in both residential and industrial buildings. Lightweight concrete is often used for insulation (thermal insulation materials).
The quality of concrete depends on the composition of the concrete mixture.
The components of concrete are water, filler, cement (the usual name is cement), additives. The interaction of the binder and water causes a chemical reaction, forming another, new compound that looks like sticky dough. Builders call it a test of cement, or cement milk. Filler is poured into it. A thin layer of cement dough envelops the filler particles and binds them (a kind of skeleton is formed that prevents deformation and shrinkage in the future). After complete solidification, the concrete mixture becomes a solid monolithic stone.
Aggregate (crushed stone, gravel, sand (or a mixture of them) accounts for about 80% of the volume, however, the number can vary. The composition of the concrete mix will determine which concrete will be the result (heavy, heat-resistant, lightweight, reinforced concrete etc.) However, it is not always possible to maintain exact proportions, especially if the builder is a homegrown lover.
Dry concrete mix, already ready, will probably be the best solution. This is a semi-finished product with metered portions of cement and aggregate, diluted with water and mixed directly at the construction site. Dry concrete mix can be stored for a long time and consumed only as needed, without changing the properties, like a ready mix.
Dry building mixes are also widely used. These are auxiliary materials, with specialized properties, used mainly for finishing (powder paints, texture coatings, "liquid wallpaper", etc.). Various mixtures (for masonry mortars, glue for porcelain stoneware and tiles, putty, leveling compounds, sanitation compounds) are combined by a cementing base. These are ready-made compositions that are sufficient to dilute with water, with a very convenient “specialization” of properties, with modified additives (plasticizing, stabilizing, changing the speed of hardening and setting, anti-frost, sealing, water-repellent, bactericidal, air-entraining, etc.).
And if more recently a concrete mix was used for finishing work (more precisely, a sand-cement mortar), now more and more they are focusing on dry mixes that allow applying layers in a centimeter or more. Cement is a mineral binder, ideally compresses, and properly selected sand "helps" it. But such a solution does not always withstand bending and tensile loads (especially if applied with a thin layer). The water holding capacity is quite low: water is absorbed into the base quickly and relatively quickly evaporates, which interferes with the final hydration of the cement, and as a result reduces strength. There are no such drawbacks in dry building mixes.
These mixtures are divided into gypsum, lime, gypsum-lime, cement and cement-lime. The aggregate can be ground limestone, fibers (mineral, organic), marble chips, building sand, metal fiber. Types of designation: for screeds and bulk floors, tiled, masonry, plaster. Special mixtures are used in:
- strengthening the foundations;
- sealing joints;
- work with wet and saline walls;
- waterproofing;
- front works (decorative);
- repair work (putty mixtures).
Depending on the type of work, the corresponding material is also selected. Of all the mixtures involved in the construction, the concrete mixture occupies about 30-40%, and the remaining 60-70% fall on dry mixes.