Stamps concrete strength - how to choose the right ?

Mark and concrete class

strength class and the brand - it's basic parameters on which you need to choose the concrete.In fact, these figures indicate the extent to which the concrete becomes strong during solidification.Typically, this occurs at 28 days after application of the mixture.That's when it gets its essential characteristics.Represented by the concrete stamp with the letter "M" and the numbers from 50 to 800. For example, the M50 has a strength of 46 kgf / cm2, and M800 - 786 kgf / cm2 (high-strength concrete).The most popular are the M100 (98 kgf / cm2), M150 (131 kgf / cm2), M250 (262 kgf / cm2), M350 (327 kgf / cm2), M400 (393 kgf / cm2), M550 (524 kgf / cm2).

concrete class is usually denoted by the letter "B" and a number from 3.5 to 80. Each class is the strength of concrete in MPa (compressive).For example, B7.5 95% can withstand the pressure of 100 MPa.The higher the class, the higher the compressive strength of the concrete.Typically, the package has all the data in a separate table.If suddenly this option is not present, it can only identify 28 day field hardening mixture.Scan concrete strength at 7 days simply useless, since its characteristics can be improved only with the passage of time.

How to choose the right concrete?

Choose one or the other type of mark and class in accordance with the building design and construction.In the event that no draft to the structure, it is necessary to understand their own.As already mentioned, the brand reflects the rate of solidification.That is, in fact, the brand M100, M300 show, what is the limit of concrete compressive strength, measured in kg / cm2 at 28 days.The higher the grade, the higher its setting and hardening of a mixture of the higher cost.It is not always necessary to choose the most expensive compositions and their use.

Yes, they are of excellent quality, but more difficult to work with them.Moreover, they are much faster than dry.Therefore, in the construction of concrete structures it is important to find a balance.Here is an example.So, for the preparatory work is often chosen M100 and M150.M200 is perfect in the construction of the foundation, pavings, sidewalks, floors screeds.

M350 - one of the most popular brands, as ideal for any critical structures.Most often it is used in commercial construction for walls, slabs, beams, etc.

Less commonly used brands like M400, M450.They are highly durable and therefore are useful in the construction of hydraulic structures and bridges.Well, M500 and M550 for domestic purposes completely used.They are needed in the construction of dams, subways and in many other cases, where special conditions are necessary.

few words about the quality of farmed mixture

If the concrete is mixed in typical field conditions, it is possible to determine its quality on a number of external signs.Firstly, indeed correctly selected composition after mixing has no gravel grains (gravel) which are not covered with the solution.Secondly, if the plastic composition is done, then it should not subsequently flow laitance.Otherwise, it can be considered properly chosen.

Third, when the rigid structure is assumed, that in appearance it resembles moist soil.Fourth, the determined quality with cone.When removed form the entire mass contained within should not fall apart.That is, it is entirely sits down and does not evolve with cement milk.Also, some coarse grains (they all need to be filled with a solution) should not be visible in it.