Ready-mixed concrete and concrete solution

For the preparation of concrete mix of cement, clean sand, gravel and water. Of importance, the choice of sand. River sand, although characterized by relative purity, has a smooth surface, so badly engaged with the other components of the mortar, and the ravine, although it is considered preferable, mixed with clay, so before applying it thoroughly washed.
In the preparation of the solution pay special attention to the ratio of sand and gravel: the second component should be about twice as much as the first. It is also important to correctly identify the required number of another component of the mortar - water. When added to remember that in the rain, sand and gravel contain up to 20% moisture, which is generally in a concrete solution, 60-75% of the total weight.
Concrete mix is ​​prepared in a wooden box with iron-studded bottom.
A measured amount of cement poured into a wooden box, add sand and mix until smooth. After that add the necessary amount of gravel, mix again, and only then add the water. The resulting mixture was again mixed thoroughly until smooth. Volume of the solution should be such that it can be spent for 50 minutes.
Strength of concrete and concrete solutions for compression characterized brand, which depends on the type of filler and binder, as well as their ratio in the mortar, and is indicated in kg / cm. Mark is selected depending on the operating conditions and soil moisture. For example, for masonry plinths, foundations and basement walls of the solution grades from 25 to 50.
Concrete is prepared in much the same way as the concrete mix, the last thing added to the gravel or crushed stone and carefully mixed mass. Sometimes, if the concrete is very expensive, for its preparation use the mixer, as in the home to get a good quality concrete is very hard.
It should be noted that the concrete M50 used only to fill strip foundations, concrete pier foundation M75 makes for wooden houses, and the M100 is used in concrete masonry basement walls in wet soils, as well as the construction of pier foundation with walls of brick or opilkobetona, cinder and arbolita.
Good mixing and subsequent plugging of concrete nearly double the strength of the concrete blocks. As a rule, laying concrete and carry trabovanie layers of 15 cm, and the last of these operations continue as long as the surface of the stone will not act laitance.
Too fast setting concrete mix leads to the formation of cracks in the array of concrete, at a time when it is solidifying his support in the wet state. To do this, 2 hours after the setting of the concrete surface is covered with hygroscopic materials - such as sawdust, shavings or sacking, which then regularly moistened with water. In hot weather the first day of the coating NW concrete surface watered every N hours, and in the next few days - twice a day. Each time after watering absorbent layer is covered with plastic wrap. A week later, the formwork is removed.
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