Concrete is often referred to as an artificial stone, because the main element of the solution is gravel or crushed stone. So that the design has maximum strength, stick to building technologies.
1
Concrete consists of cement, rubble, sand and additives. Sand needs a river or marine, belonging to the I class. Career sand is very small, with a large percentage of impurities that reduce the strength of the structure. Clay remains in concrete lumps, in frost it peels. To check high-quality sand, take a handful and throw in a container with water for a day. With a small percentage of impurities, water will be slightly muddy over the sediment if the clays are much - it gruds all the water.
2
For concrete, a crushed stone is needed - fragmented rock formation of 5-20 mm, with a rough surface and sharp corners. It binds all components in a single monolith. It is desirable to use a mixture of different sizes. Pebbles with rolled in water with places such properties does not possess. Concrete of granite and gravel rubble is highly durable. In solutions for unloaded structures, limestone or dolomite crushed stone is allowed, such solutions are cheaper.
3
For concrete, buy cement brand 500 or 600. Note that the material loses properties with long-term storage. After half a year, its strength is reduced to 50%. A year after purchasing cement, you can throw away.
4
Water from the well to obtain a solution to take care of caution - it can be salty, with sulfites and other impurities, worsening viciousness. The presence of il, oils are not allowed.
5
The foundation of the building is sometimes added frost-resistant additives, this part of the building is very cooled in winter.
6
The proportions "Cement - Sand" depend on the appointment of concrete. For responsible nodes, the ratio of 1: 2 is used for unloaded sites - 1: 5. The most common norm is 1: 3. Always crushed stone is 70-80% of the mixture. The greater the percentage of rubble, the more the loads of the concrete pebbles will take over.
7
The type of concrete depends on the amount of water - hard, plastic or cast. The most popular - plastic - it turns out if the water is about 20%. Hard concrete is used to fill the foundations. Plastic poured structures of complex shape. Cast can be used in unloaded products.
8
Mixed concrete is better in electrical concrete mixer. For home construction, the unit is suitable for 10 buckets with a capacity of up to 1 kW. Concrete can be mixed manually, but the quality of the mixture will be low - the mixture is heterogeneous, there are places where cement is not at all. Usually, it is manually mixed by small volumes (1-2 buckets).
9
Components fall asleep in a concrete mixer in a specific sequence. First, pour two buckets of rubble, 5 liters of water in the drum (100 liters) and turn on the machine. If you start with sand and cement, you will get a lot of dust. Then add the cement bucket and 3.5 sand buckets. Record the number of components that you poured into the car. Check the thickness of the mixture.
10
Pour the remaining sand and cement to the concrete mixer, based on the proportion of 1: 4 (cement - sand) and thoroughly stir until the desired density is obtained. Add rubble until the solution can lubricate pebbles (6-8 buckets). Pour water to 200-300 g, mix everything thoroughly. Record all the proportions and add 50% of the components when re-kneaded.
For home construction, concrete is taken, observing the proportion of 1: 3, but professional builders use special tables, where the additional characteristics of the components are taken into account when calculating the proportion.
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