Concrete b25 - features of the material, scope, proportions

In the construction of buildings with a large operational load, as well as in the performance of responsible load-bearing structures, they use reliable durable building materials. These include concrete grade B25, which is devoted to this article. Next, we consider in detail what this material is, what properties it has and how to prepare it.

Material Features

Immediately it should be noted that the class of concrete B25 (M350) is the most popular type of concrete in civil and industrial construction. This is partly due to the fact that modern building codes constantly increase the requirements for strength.

The strength of concrete B25 in MPa is 25. This indicator is sufficient for the construction of building foundations and other supporting structures.

The remaining characteristics of concrete B25 are also quite high:

Application area

The above characteristics of the grade of concrete B25 make its area of ​​application very extensive.

In particular, it is used for the following purposes:

• For the construction of foundations and other supporting structures;
• In the manufacture of slabs, beams and columns.
• When pouring road slabs, airfields, etc.

As mentioned above, this material has good water resistance. As a result, builders do not rarely use it when pouring pool bowls, as well as in the construction of other hydraulic structures.

Tip! If large loads are not planned for the concrete structure, then at its construction it is possible to use concrete of a lower class than B. 25. This will save a little during construction.

Concrete preparation

The composition of concrete B25 is the most common:

• Cement;
• Sand;
• Large aggregate - gravel or crushed stone.
• Water.

To improve the characteristics of concrete, plasticizers are often added to its composition. In addition, other additives can be used, for example, accelerating the process of setting to work at low temperatures.

It should also be noted that the characteristics of concrete are largely dependent on the filler. It may differ in size fractions, type of material, etc.

As the fine aggregate, you can use coarse, medium-grained or fine-grained sand.

As for rubble, it can be of different types:

• Granite;
• Lime;
• Gravel

GOST for crushed stone and gravel, allows the use of coarse filler fraction of up to 40 mm. When using larger rubble, the cement consumption rates should be multiplied by a factor of 0.97 (with a grain fraction of 40 to 70 mm).

Proportions

To obtain a qualitative result, it is necessary to strictly observe the proportions of concrete B25. For example, for the preparation of one cubic meter of solution, you will need materials in the following volume:

Note! To prepare the solution, you must use fresh cement, as over time its brand decreases. So for a year of storage material can lose up to 40 percent of its strength. Therefore, you should not buy cement with a reserve "for the future."

Concrete preparation

The required strength of concrete B25 can be achieved only with high-quality preparation of the solution. Therefore, it is necessary to use a concrete mixer, as it is very difficult to mix the solution with rubble by yourself and it is almost impossible to achieve good quality.

So, the instruction for the preparation of the solution is as follows:

• First of all, dry materials should be loaded into the concrete mixer, i.e. cement with sand and mix well.
• Then water is gradually added to the composition and the solution is stirred until a homogeneous mass is obtained.. At this stage, plasticizers and other additives may be added. For example, in the winter, you can use anti-frost additives that lower the freezing point of water.
• Lastly, solid aggregate is poured into the concrete mixer.. Before it needs to be moistened with water. The composition must be thoroughly mixed so that the crushed stone is evenly distributed in the mass.

The process of preparing the solution with your own hands is complete. The material must be consumed within two hours, after which the concrete will begin to set.

I must say that in addition to the proportions and the cooking process, the quality of concrete is affected by the quality of its components. As mentioned above, the cement must be fresh, otherwise it will not work to obtain concrete of class B25.

In addition, the quality of the sand affects the strength of the material - it must be clean, without any impurities. Therefore, before using it should sift through a sieve or even rinse.

Also stringent requirements are imposed on water. If the water is dirty, for example, recruited from a river or pond, the quality of concrete can be seriously affected. Experts generally recommend using drinking water for this purpose.

Note! Concrete solution is not necessary to prepare independently, there are many specialized companies that are engaged in the manufacture of the solution. However, in this case, its price will be higher, as transportation costs and producer surcharge will be added to the cost.

Application

The technology of working with concrete B25 does not have any features or differences.

The process of building monolithic structures is performed in the following order:

• First of all, the surface is prepared - cleared of debris, etc.
• Then formwork is performed. For this they use chipboard boards or wooden boards. To make the construction durable, use struts and lintels.

It must be said that sometimes fixed formwork is used. In this case, it can perform the function of insulation.

The next step is reinforcement. To do this, use a special reinforcing mesh or special steel rods from which the metal frame is made.

Reinforcement allows you to increase the strength of the concrete structure. The final step is directly pouring.

Formwork must be evenly filled with mortar. In this case, vibrators can be used to compact the mortar. A few days after pouring, the removable formwork is disassembled.

The important point of the casting is to ensure optimal conditions for the mortar setting and curing. So that this process takes place evenly, the first 10 days the surface of the concrete structure is moistened with water. The final set of strength occurs 28 days after casting.

Conclusion

Concrete class B25 has high performance, resulting in one of the most common types of concrete, which is used in various areas of construction. To independently obtain such material, it is necessary to strictly observe the technology of preparation, which we have considered above.

From the video in this article, you can get more information on this topic.