The reasons for which self-production of concrete may be required are not so few, for example, the remoteness of construction from roads and settlements, the small amount of required material that suppliers do not agree to bring. In any case, knowing the correct proportions of materials and mixing technology, you can prepare concrete with your own hands.
Materials
As for any building material, for the preparation of quality concrete it is important to "right" raw materials. The main components are only four: cement, sand, filler and water. General requirements - ingredients should be clean, free of foreign matter, and the first three - also dry.
Cement - the basis of quality concrete, it must be fresh, as when stored, its properties deteriorate. Most recipes are designed to use the most common cement brand M500.If only M300 or M400 is available, then correction factors should be used to recalculate their quantity. This rule is correct: to obtain concrete of a certain brand, you need to use cement in 2 times the size of the brand. Measuring cement is particularly convenient, as it is sold in bags, most often 50 kg.
For the production of concrete, sand is required for river or building, without any admixture of clay, which leads to the cracking of concrete during temperature changes.
Gravel or crushed stone of a fraction of 10-20 mm can serve as filler of .They should be homogeneous, without impurities of debris and granite chips. For the preparation of concrete by hand, it is more convenient to use filler from finer fractions, since it is even heavier, but it is more convenient to mix it with a shovel with it.
Water is suitable for water, river or lake water can include organic impurities, leading to deterioration in the quality of concrete.
Proportions
Measuring components must be strictly in accordance with the recommended proportions, as their violation leads to defects in concrete. For example, if you use more than specified in the proportion of cement, the concrete will be fragile. The most common formulations for private construction are the following concrete formulations with ratios: cement: sand: gravel
The proportions in the formulation are indicated by weight, so scales are needed, can be 20 to 30 kg canter. For example, for the preparation of the widespread concrete of the M300 grade, it is necessary to take 10 kg of cement, 24 kg of sand and 43 kg of rubble.
Water is added at the rate of 30-50% of the mass of the cement. For a denser concrete, a smaller amount of water is used, more for a more plastic and fluid( as when pouring a foundation).However, an excessive amount of water adversely affects the strength of concrete, as, after its evaporation, cavities remain in the material.
Concrete preparation process
If you have to mix concrete manually, it is better to use a large but not deep metal container, or at least a clean concreted area. A measured amount of sand and cement is poured into the container and mixed thoroughly with a shovel until it is uniform. Add rubble, and again the mixture is mixed. Then carefully, so as not to splatter, water pours in, and the concrete mixes up to an absolutely homogeneous state. Ready concrete should be used in an hour.
The preparation of concrete by hand is extremely time consuming, so it is better to use a compact concrete mixer. The working unit is poured about a third of the cooked water, cement is poured in, and mixed to a uniform consistency. Then, in small batches, sand is added. After all three components are well mixed, lay rubble and add the rest of the water. If the solution is not used at once all, then the concrete mixer should be left switched on.
It is not easy to manufacture concrete independently, even knowing the proportions. You need to pick up and accurately measure the necessary ingredients, mix them thoroughly, only in this way you can achieve quality, close to the industrial one.
