The choice of quality class for continuous footing depends on what on it is supposed loading. If build karkasnik, the house from foam concrete, panel board, M200 concrete will be the optimum choice. Heavier constructions require high-strength concrete of M350 brand.
1. In low construction by the most popular the continuous footing is. Because, what concrete will be used at its filling, durability and durability of this design depends. In the choice of quality class are guided by the following parameters: what expected weight of construction, type of reinforcing of tape, property of soil (first of all, saturation its moisture).
2. If building conditions demands the concrete foundation device (pillow from cement and sand solution) which is filled in in front of the tape device, uses concrete of M75 or M100 brand. The first is called "lean concrete". Its preparation requires brand cement not below M300 (25 kg), water (10 l), the sifted sand (334 kg). Fill in solution on the binding gravel laid on trench bottom. Height of concrete foundation should not exceed 10 cm.
3. If on continuous footing the house with relative small weight is built, for filling of the basis it is possible to use M200 brand concrete. Its preparation will require M400 portland cement above. On 1 kg of cement take 3.5 kg of the sifted pit sand and 5.6 kg of filler. As the last use crushed stone or gravel of average fraction in which the size of stones does not exceed the sizes of 20/40 mm. The amount of water has to be such that solution was fluid, but rather dense and viscous.
4. If it is going to build the heavy building: brick or concrete blocks, filling of continuous footing requires high-strength concrete of M350 brand. For its preparation use M400, M500, M600 cement. Filler, different most high strength – granite crushed stone is mixing ratio. Such concrete almost does not react to temperature drops, has water-repellent property and is resistant to influence of forces of rebound of soil. Add the ingredient providing to concrete frost resistance to solution.
5. Private developers seldom penetrate into subtleties of preparation of concrete of any given brand, being limited to the choice of quality cement and filler. Ratio of components in independently prepared structures often following: 1 parts of cement, 3 parts of sand, 30% of weight volume – filler. Such concrete cannot conform to all requirements imposed to its specific brand. Therefore at construction of the building from 2-3 floors you should not rely on personal knowledge and the equipment, and to order the factory concrete made according to construction standards.