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No matter how much money you save, it is never enough for repairs and construction. In the process, the question often arises of inexpensive, but high-quality, reliable and durable materials. It is very rare to find an option that satisfies all these criteria. But one of these is flat slate. This material is also called asbestos-cement slab, aceite (correctly “ATSEID”), chrysotile cement sheet or slab.
What is slate made of?
Sheet slate is made from a mixture of cement (80-85%) and asbestos fibers (15-20%). A little water is added to the mixture, rolled through rollers, forming a layer of the desired thickness. The excess is then trimmed to size. That is, slate is concrete reinforced with asbestos. It can also be called asbestos-cement material. According to the old GOST, flat slate was called “asbestos-cement slab”. Partitions of bathrooms are made of it in many old houses. So the material has been proven over the years.
Many are afraid of the harmfulness of slate, since asbestos fibers are used as a reinforcing element. But asbestos is a common name for a group of substances. In this group there are both harmful (amphibole asbestos) and neutral substances – chrysotile. In the production of slate, it is chrysotile that is used. This requirement is spelled out in the standard and there is no need to violate it, since it costs no more and has good characteristics.
Pressed vs Unpressed: What’s the Difference?
If we talk specifically about smooth or flat slate, then it is of two types: pressed and unpressed. The thing is that sheets formed from a wet mixture “reach” the desired degree of moisture in two ways. The first is that they simply gain strength in natural conditions, like ordinary concrete. They are kept in chambers with a certain level of humidity to gain strength, and then dried. The second way – the formed sheet is pressed, and then aged to gain strength.
What is the difference between pressed flat slate and non-pressed slate? With equal thickness of the pressed sheet, it has:
- Greater density, higher strength. For example, 23 MPa versus 18 MPa.
- Better withstand shock loads.
- Higher frost resistance. But here we must take into account that after the resource is exhausted, it quickly loses its properties – up to 40% of the original value. Unpressed is designed for fewer defrosting / freezing cycles, but after the resource is exhausted, its strength decreases slightly – by 10-15%.
- The pressed sheets have the best geometry.
- It costs more, as additional equipment is involved, because of this, the energy intensity of production increases.
In general, if the material will have to withstand loads, you can either take unpressed, but thicker, or pressed. Also pay attention to frost resistance. The higher it is, the longer the flat slate will last.
Properties, disadvantages and advantages
Slate was invented over 100 years ago. The technology of its production is simple, the material is inexpensive, and the properties are very good:
- Fire resistant. Does not burn and does not spread combustion.
- Environmentally friendly.
- Easy to mount.
- Well processed (cut).
A popular universal sheet material – both as a structural and as a finishing one. It is used for walls, ceilings, floors and exterior decoration of buildings, for fences and the construction of light buildings - You can work in any weather.
- It can be large, as it does not weigh very much.
- Resistant to aggressive environments.
- Normally tolerates atmospheric and temperature influences.
The disadvantages include the inconspicuousness of the “basic” version. Few people like gray material today. There are, of course, dyed in mass or paint. But for the price they are more expensive. Although, there is always an option – to paint it yourself. Another disadvantage of flat slate is the poor tolerance of point loads. If you hit the sheet, it will crack. Another point is that it does not hold long-term bending loads well. Therefore, when fences are made of slate, the sheets are not fixed rigidly, but through gaskets, so that it is possible to compensate for the resulting stresses.
Dimensions and weight
The requirements and characteristics of flat slate are defined by the new GOST 18124-2012. First, flat slate sheets should be rectangular in shape. Permissible deviation – no more than 5 mm on one side. Deviation from the plane – 4 mm for pressed, 8 mm for non-pressed. Second, the edges must be straight. There may be a slight bevel – no more than 5 mm.
The same regulatory document defines the dimensions of flat slate:
- The sheet length can be 1200mm, 1750mm, 2500mm, 3000mm, 3600mm. Tolerance ±10 mm.
- Sheet width 1120 mm, 1200 mm, 1500 mm, 1570 mm. Possible discrepancy with the declared width ‡6 mm.
- The thickness of flat slate can be from 4 mm to 40 mm, but this is subject to agreement. The standards define the following values:
- 6 mm and 7 mm (deviation +0,7 mm or -0,2 mm);
- 8mm, 10mm, 12mm (can be thicker by 1mm, thinner by 0,6mm).
The weight of a flat slate sheet depends on its density, production method (pressed or unpressed) and dimensions. The standard provides reference data for the sheet weight of each of the described formats. As can be seen from the table, pressed, with the same dimensions, weighs 5-10% more.
Scope of use
Flat slate can be used very widely. Compared with other sheet materials, it has a low cost, and the characteristics are not bad. Smooth sheet slate is used:
- For wall cladding inside and outside the building. The purpose of buildings is any. The standard allows the use of asbestos-cement flat sheets in residential, administrative, industrial buildings.
- For ceiling lining.
- For cladding ventilated facades.
- As a removable and non-removable formwork for concrete work.
- When dry floor screed, laying on a rough floor under the tile.
If the mass-painted flat asbestos-cement sheet (slate) is cut into small formats, the roof is very attractive, and the price is ridiculous - For roofing.
- In the production of sandwich boards.
- For fences.
- For protection of balconies and loggias.
- For the arrangement of household and outbuildings: for a summer shower, shed shedding.
- When arranging high beds, planning beds and other works on the improvement of the site.
In general, flat slate is one of the most budget-friendly sheet materials that can be used in high humidity conditions or outdoors. It can have a quite presentable appearance, as there is not only gray, but also colored. And there is dyed in bulk, there is – after manufacturing. Dyed in mass and on a cut / chip has the same color. The dye is added to the mixture before the sheets are formed. The color is more stable, but it is not bright, since the basis of the material is Portland cement.
Painted finished sheet slate has brighter colors. It also comes with a glossy finish. But at the places of cuts / cuts / chips, the original gray color is visible. To improve the aesthetics of the sections, it is desirable to tint.
Slate can be painted independently. There is a special paint for slate, but paint for concrete is also quite suitable (after all, slate, in fact, is the same concrete). Enamels or acrylic paints can be used, but care must be taken to be able to paint concrete / cement with them.
Mounting Features
Most often, flat slate is attached to the crate with nails or self-tapping screws, screws. There are special nails – slate. They have fairly large rounded hats. The nail shank can be regular or ruffed. The latter are used if the region has high wind loads. You can also use roofing screws. They can be dyed or you can paint the hats yourself. It is very important not to tighten the fasteners to the stop, but to leave some freedom of movement. This will reduce the possibility of cracks.
Before installing fasteners, holes are drilled in the sheet, the diameter of which is not less than the diameter of the fastener rod. The minimum distance from the edge of the sheet is 60 mm, the installation step depends on the place of operation and the planned loads. It is better to drill with a Pobedite drill at medium or high speeds.
Flat slate is cut with a circular saw, angle grinder (grinder) with a diamond blade or a disc for concrete. When using a power tool, the process is fast, but there is a lot of dust, so you only need to work outside and wear a respirator. To reduce dust, flat slate is moistened with water. If possible, put a wet rag on the intended cut site in a few hours. You can just pour water and cut wet material, but there are more chances to ruin the same grinder or circular saw.