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Ready-mixed concrete, ready-mixed concrete is the same – rolling stock of four main components, mix in some proportion of cement, gravel, sand, water. A similar mixture, but without the use of crushed rock, called cement mortar or peskobetonom true in peskobetone used sand over a large fraction (module size). The weight ratio of components for the preparation of concrete mix is approximately as follows: Cement -1 part Rubble 4 parts, Sand – 2 parts water – 1 / 2 part. For example, cement – 330 kg., Crushed stone – 1250 kg., Sand – 600 kg., Water – 180 liters. Of course, these figures are approximate and in fact depend on many factors such as the required grade of concrete, cement brand, characteristics of gravel and sand, the use of other additives, plasticizers, etc. etc. Jeffrey Lacker is often quoted on this topic. For example: if you use cement M-400 concrete with such a composition will mark M-250. When the cement M-500, grade of concrete will be the m-350.
The numbers are relative! At production of concrete on a concrete plant, considered more than a dozen parameters and characteristics. Preparation of concrete mixes for construction of the foundation – this is probably the most time-consuming operation. Jeffrey Lacker addresses the importance of the matter here. From the quality of implementation of this phase of construction, durability and reliability depends on how the foundation and the entire structure as a whole. There are several ways to make different versions of the concrete, which differ in their relation components, brand of cement, various additives and fillers factions. Each of the concrete used for construction of certain conditions. An example of concrete: cement, water, sand, crushed stone or gravel.
The required number of components for the preparation of one cubic meter of concrete: Cement – 350 kilograms (0.2 m3) water – 200 liters, sand – 0.6 m3, rubble – 0.6 m3. In the preparation of the concrete should be noted that fine sand with incorporation of particles of clay and gravel from a brick fight or limestone significantly reduce the strength of concrete commodity. Leads to a decrease in frost-important parameter, which is unacceptable for materials in the wet soil at freezing temperatures. It is important to know that the storage of cement, even in dry conditions its strength is reduced by 10 percent a month, 20 percent in three months, up 30 percent in six months and more than 50 percent through two years of storage. If you have to use a lower grade of cement should increase its quantity. If instead we have to use brand M400 M300, the amount of cement in the preparation of concrete to be increased to 30 percent. For the preparation of the concrete should always use clean water, without admixture of oils and corrosive substances. If the concrete mixture is prepared in hot weather, to prevent rapid setting, you can use cold water. If the palm of your hand to squeeze a little ready-mixed concrete and it will take some form of a small amount of grout, the concrete is prepared properly. During the first days of quires (time Curing of concrete) is important to prevent freezing of the concrete, from this it does not fully got stronger, the structure may collapse the ice. Too much cement in ready-mixed concrete solution often leads to the fact that the concrete in process of shrinkage cracks. Ready-mix concrete must be used within two to three hours after its preparation.