When constructing a private home, selecting the appropriate concrete grade for a strip foundation is essential. Your home’s foundation serves as its structural backbone by offering the required stability and support. Making a bad decision now can result in expensive repairs and structural problems later.
There are different grades of concrete, and each has unique qualities and strengths. The type of soil, the weight of the structure, and the climate in the area all affect the grade that you require. Comprehending these variables will facilitate your decision-making process and guarantee the durability of your residence.
This post will discuss the various concrete grades that are appropriate for strip foundations, their features, and how to select the best grade for your needs. You’ll know for sure by the end which grade will give your house the strength and longevity it requires.
Concrete Grade | Recommended Use |
M200 | Suitable for small, light structures with minimal load. |
M250 | Good for medium-sized houses, offering better strength and durability. |
M300 | Ideal for larger homes with heavier loads, providing strong and reliable foundation support. |
M350 | Recommended for large, heavy buildings with significant structural demands. |
- What brands and strength classes of concrete exist?
- What does the brand mean?
- Scope of application of various types
- What requirements must it meet?
- Frost resistance
- How to calculate the load
- Which brand is suitable for the strip foundation of a private house?
- Concrete proportions
- How to mix it correctly
- How to calculate quantity
- Useful video
What brands and strength classes of concrete exist?
Concrete has two quality indicators that are indicative of its nature:
Megapascal tensile strength is referred to as the concrete class.
Differentiate:
- Compressive strength class (denoted by Latin B).
- Axial tensile strength class (Bt).
A guaranteed strength value that corresponds to GOST 26633-91 is known as the concrete class. The allowable error level is 13.5%, subject to production conditions, technological features, and other considerations.
Although there are classes ranging from B3.5 to B80, concrete classified between B7.5 and B40 is typically utilized. This is because low values are weak, high values are only used on special structures and are unnecessary in regular construction, and extreme values are only rarely needed.
For a given indicator, the average strength value is indicated by the concrete grade. In the construction industry, brands are utilized more frequently because not all manufacturers uphold the class value.
When the coefficient of variability is taken into consideration, concrete quality of the same grade can fall into several classes with values that are relatively close to the actual indicators of this material.
What does the brand mean?
A concrete’s grade is a numerical representation of a specific attribute.
Existence
- Strength grade (M).
- Frost resistance grade (F).
- Waterproof grade (W).
The most useful grade in practice is the M, which offers the most crucial details regarding the content’s quality.
The values represent the compression limit in kgf/cm2 and range from M5 to M800.
Scope of application of various types
Concrete’s strength and resistance to external loads define its range of applications. A material’s capacity to tolerate pressure is the primary criterion for quality.
The area of use is determined by this indicator:
- Concrete grades from M5 to M35 are intended for filling voids in auxiliary elements or footings.
- M50-M100 are used for the preparatory layer before pouring concrete bases (t.n. footing).
- M150 is used for the manufacture of non-critical structures in low-rise construction.
- M200-M300 is the most common material in private or low-rise construction, capable of solving most problems in this area. Used for foundations, wall structures and other elements.
- M400 is used for monolithic foundations of large multi-storey buildings, structural elements, floors, etc.P.
- M550 and higher grades are used for the manufacture of critical elements of special structures, used in the construction of subways, hydroelectric power stations, etc.d.
The M200 and M250 brands are the most popular in private construction, and their quality is more than adequate to address current issues.
Brand is an antiquated classification scheme that dates back to the Soviet Union. The idea of "class" is used in today’s standards, but since most builders have not yet adjusted to the new units of measurement, the idea of "grade of concrete" is still applicable.
What requirements must it meet?
Concrete must have a high strength and the capacity to support external loads. The building’s weight and the loads caused by frost heaving the soil on the sole (from bottom to top) and side surfaces are the main forces acting on the belt.
It is necessary for the monolithic concrete strip to be able to bear all loads and impacts that may arise, including the potential for freezing and saturation of moisture. When they interact with groundwater in the winter, the majority of them emerge at low temperatures.
The predicted loads—which account for factors like soil movement during the off-season, frost heaving effects, and house weight—are the criterion. The combination of these indicators—which require specific computations or determination using tables in the SNiP appendices—determines the choice of material.
Frost resistance
A material’s ability to endure a specific number of freeze-thaw cycles without losing its performance characteristics is indicated by its frost resistance. Values for this variable, denoted by the letter F, range from 50 to 2000 cycles.
As concrete brand name rises, so does its resistance to frost. N For instance, the M350 value F is 200 if the concrete M250 has 100. The material’s high coefficient of variability accounts for the absence of direct dependence at the same time.
This indicates that although it is extremely unlikely, concrete relatively weak brands can have high values of F. The expected value of F can only be obtained with a complete guarantee in higher brands (or classes) of concrete.
How to calculate the load
By adding up all of the effects on the tape, the load on the strip foundation is calculated.
They are considered:
- Own weight of the base.
- The weight of the house, the total weight of the walls, ceilings, roofs, structural elements, increased to a special coefficient (taking into account the weight of furniture, property and other interior items).
- Loads from the weight of snow in winter.
- Wind loads.
- Impact of frost heaving.
It is strongly advised against calculating these impacts independently. Errors are unavoidable in such computations without experience, and the results could be disastrous for the building as a whole or the foundation.
It is essential to get in touch with a specialized company and request a qualified calculation of the belt’s loads and load-bearing capacity.
An online calculator, which can be found on the Internet, is an alternative. They can offer reasonably accurate data, which is typically enough for building a private residence. You should perform the calculation twice on multiple calculators for increased reliability and to guard against calculation errors.
Which brand is suitable for the strip foundation of a private house?
The following standards can be used to identify the concrete grade that best fits the current circumstances:
- Design load on base.
- Qualitative indicators of the soil on the site, its type and composition.
- Groundwater depth (GWL).
The load on the belt, the influence of soil, and soil water are the primary indicators. These are extra parameters that let you add to and clarify the data that was collected. It is important to remember that large, heavy buildings require extremely precise calculations.
Private homes are typically lightweight and don’t require a lot of intricate calculations. The most common grade of concrete used is M200; in more challenging situations, M250 or M300 are selected.
Since a private home’s weight is not particularly high, using heavier materials is extremely rare. In the event that particularly problematic soils are present, the foundation design should be changed from strip to pile-strip or pile-grillage.
In these situations, it is not advisable to use concrete with stronger grades because the soil pressure becomes excessively high and unstable, making it risky to rely solely on the tape’s strength.
Concrete proportions
Concrete’s composition consists of the following:
- Cement.
- Sand.
- Water.
- Filler (crushed stone of different fractions depending on the type of concrete).
If producing concrete grade M200 is required, you will require the following materials for every 1 m3:
- Cement M400 – 325 kg.
- Crushed stone – 1300 kg.
- Sand – 1300 kg.
- Water – 205 l.
Regarding M250 concrete:
- Cement M500 – 320 kg.
- Crushed stone – 1280 kg.
- Sand – 1280 kg.
- Water – 205 l.
Take note! For every ten millimeter, the amount of crushed stone is indicated. Owing to varying component quality, the material’s composition may differ slightly between manufacturers.
Selecting the appropriate concrete grade is essential when constructing a strip foundation for a private residence in order to guarantee the stability and lifespan of your building. The most frequently suggested grades are M25 or M30 because they offer the strength and durability required to support most residential structures. These grades are perfect for most soil types and climate conditions because they strike a balance between performance and cost. You can guarantee a strong foundation that will endure over time and serve as a safe and secure base for your home by choosing the right concrete grade.
How to mix it correctly
It is best to make concrete by hand only for small buildings with a shallow tape immersion depth and, therefore, a limited quantity of material. It is preferable to order ready-made concrete and have it delivered in a mixer straight to the site for large bases because the technology necessitates pouring the entire tape at once.
By choosing this option, you can prevent pouring delays—which can be hazardous because they can result in the appearance of poorly connected areas. Such flaws prevent a tape from withstanding operational loads.
If you choose to mix your own concrete, you will need to get ready all the ingredients and a concrete mixer. It is available for rent for a few days, so purchasing it is not required.
Sand might contain a variety of clogging materials, so you’ll need a sieve for this process. An armored mesh from a bed is typically used in private construction, installed at an angle over the receiving container.
Garbage and foreign objects remain on the mesh after sand is shoveled through it with a shovel and placed into a box or trough. Sand from washed rivers that hasn’t had any clay added is the ideal choice.
Depending on the volume, a gravity concrete mixer can produce anywhere between 60 and 500 liters of solution per batch. To make sure that the component ratio is correct, you must know the volume.
In a concrete mixer, the necessary proportions of sand, crushed stone, and cement are combined and stirred until a smooth mixture is achieved. Water is then added gradually. Ready-made concrete is a plastic mixture that doesn’t have any lumps of cement or sand and has filler spread evenly throughout.
When preparing small batches of concrete, you should begin by laying sand, then gradually add cement and filler. This will remove lumps from the solution and improve the mixing of the sand and cement.
How to calculate quantity
To ensure that all the components are stocked in the necessary volumes, the amount of concrete must be calculated. It is advised by experts to compute each straight segment of the tape independently before adding up the results.
It turns out that the corners are counted twice in this instance, but that’s okay because it gives you access to a limited amount of material.
The cross-sectional area of the tape is first calculated in the calculation. Its width times its height yields this result.
The same units must be used for all calculations, ideally meters. The material’s volume will then be stated in cubic meters, making it easy and error-free to determine the quantity of components.
The length of each straight segment of the tape, measured along its outer perimeter, is successively multiplied by the tape’s cross-section. The length of the center lines is used to compute the areas beneath interior walls.
After adding the volumes of each section, the result will, plus or minus a margin, indicate the quantity of concrete needed.
Useful video
This video will teach you how to pour concrete and which kind is best to choose:
For a strip foundation, selecting the proper concrete grade is essential to the longevity and stability of your individual home. The most frequently suggested grades are M200, M250, and M300 because they offer a cost-effective and balanced combination of strength and quality. These grades guarantee that the foundation can sustain different environmental stresses and support the weight of the house.
The kind of soil, the weather, and the total weight that the foundation will support should all be taken into account when choosing the concrete grade. While M250 and M300 are better for heavier buildings and less stable ground, M200 is frequently appropriate for lighter structures and stable soil. Seeking advice from a structural engineer can assist you in selecting the best option for your particular circumstance.
Recall that the materials and mixing technique have an impact on the final product’s quality as well. Make sure you always use premium ingredients and mix them according to the right methods. In the long run, it can be expensive to fix structural problems and cracks caused by subpar concrete.
In conclusion, if you invest in the right concrete grade and make sure everything is ready, your private home will have a solid and long-lasting foundation. You can enjoy your home with peace of mind for many years to come by giving this careful consideration. It will also save you time, money, and stress.