As you know, the durability and strength of any structure depends on the quality of the foundation on which it is based. In private construction, as a rule, 3 types of structures are used, these are columnar or pile, slab and the most common tape, which we will talk about. The brand of concrete for a strip foundation of a private house is the most important indicator of its quality.
What is a strip foundation
The tape view of the foundation structures is considered the most common.
It is a reinforced concrete tape, buried in the ground and passing a closed loop under all the bearing walls and walls of the building.
- Instructions on the arrangement of this type of structures of great complexity is not. A trench is dug out, a reinforcing iron frame is laid in it and all this is poured with liquid concrete.
- But, despite the apparent simplicity, perhaps the most difficult point here is the correct definition of what brand of concrete to use for strip foundations.. This choice is influenced by a number of components.
What factors influence the choice of brand composition
Unfortunately, there are no universal recipes, the price is not always a fundamental factor. After all, even expensive formulations have their own recommendations and restrictions on use.
Dependence on the weight of the building
If you want to build a house with your own hands, and you do not have a finished project with the prescribed recommendations, then first of all, you should pay attention to the total weight of the building. This is the first indicator from which repelled when selecting a brand of composition.
Here are some general guidelines:
- A prefab house with a height of 2 floors, in most parts of our country, will stand comfortably on a reinforced concrete foundation, covered with the M200 brand.
- For 2 - 3 storeyed log buildings, as well as for houses built of foam concrete, gas silicate blocks or other cellular concrete, M200 - M300 brands are recommended.
- For heavy, capital buildings built of brick, solid concrete structures or other heavy materials, it is recommended to use the mark from M300 and above.
Much depends on the geology of soils in this area, their composition and how deep the groundwater lies.
- The most favorable are sandstones and rocks. They can pour concrete M200 - M250.
- A rather big problem is clayey soils and loams. The fact is that these soils are prone to heaving during freezing. That is, they freeze through unevenly and are capable of squeezing out a shallowly embedded strip foundation in some places, which leads to a general deformation. In this case, you can do in two ways.
- First, to deepen the structure to a level exceeding the average total soil freezing in the region.
- Secondly, it is possible to equip the tape-column, well-reinforced foundation. This is when at the key points the supporting concrete pillars are poured to a considerable depth, which stabilize the entire structure.
Important: it should also be noted that starting with the M200 grade, if necessary, the cutting of reinforced concrete with diamond circles is already used, and for penetration diamond drilling of holes in concrete is used.
Common brands of concrete
By production of concrete of different brands for the bases, cement M 400 is most often used, but in different proportions.
- M100 - used as an underlaying cushion when building roads, laying deep foundations or pouring screed for the floor.
- M200 - suitable for shallow foundations based on stable soils. They are flooded with basements and all sorts of open areas.
- M250 - used for casting fences, various kinds of stairs and tape-column structures.
- M300 - is considered the most popular brand for pouring the foundation. It is successfully poured into the vast majority of well-known foundations, can be used in a wet environment.
- M400 - used for casting underwater structures, bridges and other capital structures. It is used to build houses in extreme conditions.
- M500 - used for pouring steep structures, repair of roads and structures, or as an additive.
Important: the quality and strength of concrete is greatly influenced by the so-called shrinkage factor - the lower it is, the stronger the construction will be. It can be reduced with the help of special additives. When using vibrating machines it is possible to fill in more hard and dry formulations.
What else you should pay attention
- There is another marking characterizing the strength class of the hardened composition. It is designated by the letter "B", characterizes the safety margin for compression and is measured in megapascals.
Important: the strength of concrete may vary over time. Active curing takes place within 28 days from the moment of casting. Further, these processes slow down significantly, but do not stop.
- The level of strength and grade of concrete indicators related. According to GOST, each concrete grade corresponds to its level of concrete strength; here are some key indicators:
- B7.5 corresponds to M100
- B15 corresponds to M200
- B20 corresponds to M250
- B22,5 corresponds to M300
- B25, B27,5 correspond to M350
- B30 corresponds to M400
- B35 corresponds to M450
- For our country, the indicator of frost resistance is also relevant, it is marked with the letter “F” and a certain number after it. The number indicates how many times the structure may freeze. For more of the country, F200 is sufficient; the more thaws in winter, the higher this figure.
- You should also pay attention to the indicator of resistance to high humidity. It is indicated by the letter “W” and the number after it.
It is worth considering the fact that the higher the class, the quality and of course the price of concrete, the faster it will clutch. Experts advise to pour high-quality compounds for 1 day. Accordingly, to quickly fill in such a foundation with your own hands will be problematic, so here it is better to resort to the services of construction firms. In the posted video in this article you can find additional information.