How to prepare concrete

Information on how to make concrete, useful in many construction works – in the construction of the foundation, installation of partitions, concrete floor, etc. This operation is one of the most labor-intensive and dirty, and the quality of these works depends on the durability and reliability of the entire structure as a whole.

 

Components for concrete mix

There are several ways of preparing concrete mixes, which can vary the ratio of components, type of cement, additives and fillers fractions. Each specific composition is used for the specific conditions of the construction.

Usually concrete prepared from the following components:

  • The Water;
  • Cement;
  • Building sand;
  • Gravel or crushed stone.

Cooking one cubic meter of concrete will need about 350 kg of cement (0.2 m3), 200 liters of water, 0.6 m3 0.6 m3 of sand and gravel. If it is necessary to produce 100 liters of a concrete mixture, the amount of the ingredients will be as follows: Cement – 3 bucket (30 kg), crushed – 8 buckets (100 kg), sand – 5 buckets (70 kg).

As the binder in the preparation of concrete often used cement type is used 400. If the lower cement brand, its quantity increases. For example, when changing the brand M400 M300 on the amount of cement should be increased by 30%.

Water to make concrete mix should be as clean as possible, that is, without the inclusion of any impurities, oil or corrosive substances. If the concrete mixture is cooked in very hot weather, you can use cold water to avoid setting the mixture ahead of time. The required amount of water is difficult to determine in advance, because here plays the role of moisture gravel and sand, and cement vlagopotrebnost. The necessary displacement of water is determined already in the process of mixing the concrete mix. The technology of its preparation is as follows: first mixed dry components – crushed stone, sand and cement, they are thoroughly mixed until smooth, and then there is added to the water in small portions. The consistency concrete mix should resemble a thick cheese, but at the same time, the mixture should not be too fluid. Cooking it should be at a positive temperature of the ambient air.

Sand for concrete mix must take a large, clean and without additional inclusions – clay, silt, organic particles. Better to sift the sand to avoid foreign particles. On how clean the sand depends strength of concrete, and the use of dirty sand can cause an increase in cement consumption (about 10-20% of the standard rate).

Crushed better to use the fine fraction (about 2-20 mm). The best option is the rubble of natural rocks, crushed gravel or river. Possible and the use of artificial slag, expanded clay, gravel, but it should be borne in mind that the use of such fillers reduces the life of the building.

Crushed stone (aggregate) better to use small (5-20 mm fraction). Optimal results are obtained by the use of natural gravel rocks, small river or crushed gravel. Also possible to use artificial gravel, broken bricks or limestone, slag, expanded clay, but it should be remembered that the concrete structure by using this kind of aggregate will be less durable. This also leads to a reduction of the concrete mix parameters hardiness, which is unacceptable for materials which are in a moist soil at low ambient temperatures.
Check the availability and correct preparation of concrete as follows: in the palm of your hand squeeze a small amount of ready-mixed concrete, and he must take some form with the release of a small amount of liquid – laitance. During the curing of concrete (about 10 days), it is important to prevent freezing of concrete because of the appearance of ice can break its structure is not strong. It should be remembered that the excess amount of cement in the concrete mix can lead to cracking of the concrete during the shrinkage. Preparation of the concrete mixture should be used within a couple of hours posleee batch.
Methods for preparation of concrete mix

If you need a large amount of concrete, it is necessary to use a mixer (it can be rented), and the average volume is more convenient to knead by hand.
Manual method of preparing a concrete mix. Need two buckets, one for the cement (it should be clean and dry), and the second for the sand and aggregates (crushed stone). It is also recommended to have two spades. Ingredients should measure as accurately as possible, thus aligning their level at the edge of the bucket. When filling the container with sand or cement should knock on the side of the bucket shovel to compact loose materials. On a rigid flat surface and mixed gravel and sand, then the resulting hill make a recess is added thereto and the mixture of cement until uniform in color. Then again, in a pile of dry material make deepening and add to it water from a watering can. The mixture was spiked with the edges of the recess with water until until it is absorbed, and then chopping the ingredients mixed shovel movements. Water was then added, and again raise the concrete below the heap until homogenous.

Check the readiness of the concrete in the following way: the back of a shovel to make a series of edges, moving the tool in his side. In this case, the concrete surface should be smooth and even, and its ridges remain the same shape and does not fall off.
Automatic method for preparation of a concrete mixture. The mixer must be installed on a flat surface and before turning on the engine to make sure that the drum is in the upright position. With the help of a bucket in the drum is charged half gravel and pour the water. Then small portions alternately add cement, sand and coarse aggregate balances. The mixture should be stirred for a few minutes. Then tilt the drum, cast a small number of concrete vtachku to check availability. If it is not ready, it is loaded back into the drum and continue stirring.
According to the materials of the website “The secret garden” www.secretdachi.ru Tips and Tricks cottages.

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