Concrete is one of the oldest building materials. Excavations of ancient places of human habitation on Earth have shown that its use began over 6 millennia ago. And at present, it remains, perhaps, the most common of the building materials. Let us consider in more detail one of its varieties - B25-concrete.
Concrete quality
Compressive strength is the main quality indicator of concrete. This characteristic that determines the class of concrete is indicated by the letter "B" (Latin) and the numbers corresponding (in kg per square cm) to the permissible load on it. So, the B25 concrete class can withstand a load of 25 kg / sq. see Concrete structures of this class, taking into account the coefficients, are able to withstand a load of 327 kg / sq. cm, which corresponds to the strength grade M350.
Workability
This characteristic determines the performance of concrete when it is used. In accordance with GOST 7473-94, this characteristic is identified by the letter "P" and a number from 1 to 5, corresponds tomovable concrete with a stiffness of less than 4 seconds and is subdivided according to the draft of the cone. In this case, the draft of the cone is (in centimeters) 1-4, 5-9, 10-15, 16-20 and over 21 for grades from P1 to P5, respectively.
Scope of application
Concrete B25 (grade M350) has been very popular lately, due to tougher project requirements and increased control over their compliance. This is the reason why this brand began to occupy the highest statistical positions in sales of concrete products.
High strength characteristics are provided by a large amount of high-quality cement in the composition of B25 (concrete). Therefore, this material is most applicable in the construction of multi-storey buildings, for the manufacture of heavily loaded reinforced concrete structures (beams, ceilings, columns), including those designed for operation in aggressive conditions.
In its composition, B25-concrete mainly contains, in addition to cement, crushed granite or gravel and washed river sand. On the building materials market, it can be ordered with delivery in concrete mixers in the form of the so-called ready-mixed concrete with mobility P2-P4.
Concrete B25 (grade M350) is characterized by high values of frost resistance and water resistance. Therefore, it is widely used for arranging monolithic foundations (slab, columnar, pile-grillage and tape), as well as concrete stairs. From it in private households (and in the industrial sector) bowls of pools, monolithic floor slabs andwalls. B25 concrete is very strong and resistant to abrasion. This brand is used, in particular, for the production of airfield road slabs, which are used in exceptionally severe weather conditions. In commercial construction, it is also widely used to reinsure and increase the reliability of buildings and other facilities.
Concrete B25: price
The cost of this brand of concrete in modern conditions varies among manufacturers in a fairly wide range. It depends on factors such as proximity to quarries-sources of raw materials and consumers of products, the availability of its own warehouse, transport and sales base, and finally, on the reputation of the manufacturer in the building materials market. The cost also depends on the degree of concrete mobility: the higher it is, the more expensive the material. The price also varies depending on the filler components. Gravel-based concrete is usually cheaper than crushed stone-based material. Even cheaper is the material from secondary crushed stone obtained by crushing concrete structures. On average, B25 concrete can be purchased (excluding delivery) at prices ranging from 3,000 to 3,800 rubles. for m3.
Make your own
In cases where small volumes are required, B25 concrete can be produced on its own. To do this, mix cement, sand and filler in the following volumetric proportions: for cement M500 - 1:1, 9:3, 6; for cement M400 - 1:1, 5:3, 1. Water is added in an amount that ensures the desired hardness. Whereinsome rules must be followed:
- use only clean tools and water;
- it is better to use washed sand, gravel or crushed stone (clay impurities significantly reduce the strength of the material);
- you can not add water after mixing the solution (when it is added, the strength of the products is lost);
- use the solution within one hour after preparation.
As a filler, you can use gravel, crushed stone of granite rocks, limestone or secondary. To obtain concrete grade M350, fillers such as expanded clay, slag and other porous rocks are not used, which do not provide the required strength of the material.
Thus, in this article we reviewed information about one type of concrete, the most applicable for structural products and high-strength buildings. We hope that the information provided in the article will be useful to you.
