Exposed aggregate concrete: methods for making a coating
Exposed Aggregate is a kind of concrete surface that resembles a mosaic. This effect is achieved by adding granular filler. The granularity of the mortar used for pouring concrete structures allows you to get a little rough coating. But the surface can be as flat and smooth as possible, reflecting the glare of light, for which the method of grinding and subsequent polishing is used.
Mosaic concrete is often used for pouring floors. Granular-filled floors can be seen in business centers, in large stores, in educational and medical services. Often such floors are made in private homes, as well as in luxury apartments. Coatings can have simple or complex drawings, patterns.
Granular concrete can also be found on the street. It is used for the construction of roads, sidewalks, driveways, surface design pools. This concrete can be seen as a finish of the walls, facades of houses.
What determines the result of work
The pattern of mosaic concrete always turns out to be original. The result of applying this technology depends on several factors.
1. The size of the grains.
Grains can be large in size. In this case, the filler has a grain size greater than 5 mm. Crushed stone, which has an angular shape, or gravel, which has a rounded shape, is used as a filler. The filler may be stone chips – marble, granite and others, as well as various materials, which we will tell you about below. Grains can be small in size – less than 5 mm. As a rule, sand is used as a filler.
2. The structure of the filler.
The filler in its structure can be dense or porous.
3. Features of the material by origin.
The aggregate may be of natural or artificial origin. Natural materials are, for example, chips of marble or granite.
4. Application by type of concrete.
Aggregates exist that are designed for lightweight concrete. There is a material that is used for heavy concrete mixes.
The most common aggregates in terms of price for concrete are considered to be gravel, as well as crushed stone, as they differ in low cost. For these materials, grain size is different and often even very large. Crushed stone is classified as pure material. In turn, gravel does not differ in similar purity, it contains impurities. Crushed stone has an uneven surface, which contributes to a better setting of cement mortar.
If we talk about popularity in terms of decorativeness, then the most common is considered to be a crumb of natural stones, for example, basalt, granite, limestone, marble. Artificial fillers often compete with them, for example, colored glass, which has undergone a processing process and can be used as a concrete filler. In principle, any material can be added to the cement slurry. You can find coatings that are made using, for example, seashells.
It should be noted that the degree of quality of the filler depends on the level of mineral content, on the grain fraction, as well as on what it is in strength. It is important that the filler has good frost resistance. Then you can guarantee that the concrete will withstand excellent temperature conditions, characterized by low rates.
Due to the fact that the filler is able to change the properties of concrete, several requirements are imposed on its quality. So, in fillers with different grain sizes, a certain ratio of grains with different sizes should be observed. This requirement allows for maximum saturation of the cement slurry.
Another mandatory requirement is that the filler must not adversely affect how the cement hardens. It should not impair the properties of concrete, namely its strength and durability. Increased requirements are imposed on the frost resistance of the filler, on its mineral composition and grain characteristics.
Fillers must meet certain purity requirements. If there are a lot of impurities in the material, and the grains themselves have a coating of dust, silt, then as a result of its use, the adhesive properties of concrete will deteriorate significantly. Impurities may be present, but in a volume that does not exceed 1%.
It is important to understand that the quality of the filler used directly affects the quality of the resulting concrete coating. Our masters are well versed in these materials and can always advise what type to choose, so that the quality of the finished coating is exactly what a particular client wants to get.
Methods for making a coating
Masters can use different methods for the manufacture of mosaic concrete. Often used technology in which the filler is added after laying the cement mortar. The filler is evenly distributed over the still concrete, and then compacted using special tools. As a result, the filler is pressed into concrete.
Granular material can be immediately mixed with cement mortar. This is done at the production stage. Masters in this case use a ready-made mixture. However, ready-made mixtures can cause a rise in the cost of laying mosaic concrete, since it is necessary to use such material in a large volume.
When laying concrete with aggregate, experienced craftsmen can create different coatings.
- It may be a coating with contrasting areas. Different sections of the coating are made from a solution with a different filler, or when laying the same material, different methods of manufacturing the solution are used.
- Plots have clearly defined borders, for which wooden planks or decorative elements are used.
- When laying the mosaic coating, different concentrations of filler are used.
Exposed Aggregate – Simple Technology
How to make mosaic concrete? The simplest option is to use a filler in the form of small pebble stones. How it’s done? As an example, take the construction of a track on a land plot. After the area under the future path is marked, limiters in the shape of the path are installed, cement mortar is poured. After a certain time, when the cement hardens a little, the filler evenly spreads over the entire concrete surface. If the track is small in size, then you can scatter the filler with your hand. When working on a large area, this procedure can be performed using a shovel. It is important to do everything carefully, evenly, so that in the end you get a beautiful track with evenly distributed filler.
After the filler is scattered, the craftsmen use a flat tool. With this tool, they pass through the filler, gently pushing it into the concrete. It is necessary to monitor the uniformity of pressing the grains of the filler in order to exclude the appearance of dents on the concrete surface. It is necessary to maintain a constant pressure when pressed when processing concrete over its entire area. The pressure level when pressing the tool should be such as to ensure that the grains of the filler are pressed in until they are hardly visible.
Features of the device mosaic concrete floors
If concrete with a filler is used for the construction of floors in rooms, then after direct laying, the grinding and polishing method is always used. Polishing allows you to give the floors maximum evenness. Polishing gives the floors extra beauty. Their surface begins to shine – it is very beautiful.
In the course of grinding and polishing work, special equipment is used, equipped with abrasive wheels. After grinding, the coating must be thoroughly cleaned. When grinding, stone and cement dust is formed, and it must be removed before further polishing is performed.
There are rules that are mandatory in the construction of mosaic floors. So, work is performed at an ambient temperature of at least +5 degrees Celsius. The grain size should not exceed 0.5-12 mm. To give plasticity to the solution, water is added to it, as well as a special substance based on lime. When compacting, a manual roller is used. To improve the quality of the finished mosaic coating, the process of drying takes place under a layer of sawdust. Drying time is approximately 7 days, after which you can begin the grinding process.
Benefits of Exposed Aggregate
Mosaic concrete pavement has several advantages:
- Beautiful appearance, which is achieved by adding granular filler. Sanding and polishing results add to the beauty.
- High strength – concrete, which is characterized by a high degree of strength, in combination with a solid filler allows you to get a very strong surface;
- A variety of color, texture, which is ensured by the characteristics of the filler;
- High wear resistance – a mosaic concrete coating for a long time even with intensive use does not change its original properties;
- Resistance to temperature changes – a change in ambient temperature does not affect the quality of the concrete coating;
- Small degree of shrinkage – concrete with a filler is subject to less shrinkage during drying;
- Mosaic coating does not require special care. If it was qualitatively executed, its repair will not be required for many years;
- Low price – concrete with granular filling, for all its impressive decorative effect, is inexpensive, especially when compared with coatings that are completely made of marble or granite.
The filler significantly reduces cement consumption. Its volume exceeds the volume of cement used, which as a result affects the cost of the finished coating – it turns out to be more affordable.
The filler added to the solution increases the resistance to cracking. Concrete is often deformed due to a high degree of shrinkage, as a result of which cracks appear on its surface. The filler promotes compaction, acts as a rigid base, as a result of which cracks do not form on its surface.
The filler allows you to increase the degree of elasticity of concrete. Concrete receives additional rigidity, which reduces the likelihood of concrete deformation under load. It excludes situations when the concrete coating begins to move.
If the filler is light in weight, has porosity, it helps to increase the degree of thermal conductivity of the finished concrete coating.
That is why mosaic concrete is often used in the construction of walling, as well as structures that have good thermal insulation properties.
There are special fillers that can give concrete the properties of resistance to penetrating radiation.
Exposed Aggregate Price
The cost of Exposed Aggregate varies in a wide price range: from $ 45 to $ 180 per 1 square meter. The price of the finished coating depends on many factors.
1. What is the size of the area where the mosaic coating will be laid.
2. Type of materials to be used. As we have already said, the use of ready-made mixtures can cause a rise in the price of the finished coating. The cost of the granular filler will also increase the price, which depends on its features, as well as the extent to which it will be needed, if necessary, to achieve the result that the customer wants to receive.
3. The type of method that will be used by the masters, especially the styling. If the client wants to get a contrast coating or with a special pattern, then you will have to pay more than for laying using a simpler laying method.
4. Performing additional work. If you are making a mosaic concrete floor in a room, especially where you need to make a beautiful polished floor, then the list of works includes grinding and polishing.
Exposed Aggregate is a technology that allows you to create special concrete coatings. This process requires the use of a granular filler. Features of the granular filler affect the result of the work performed. But for the coating to turn out to be of high quality, it is necessary to ensure the participation of professional masters. They will be able to achieve the result that the client wants to get.
It is important to note that often concrete coatings with mosaics are distinguished by decorative originality. Their construction is a real art. If you do not have experience in this art, then the result of the work will not be expected. You need to be able to work with granular filler, precisely performing the task that the client set. And only experienced craftsmen can handle this.